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Fats and the Brain

Updated: May 1, 2023

Dr Oliver Finlay



KEY POINTS


· Fats are one of the essential nutrients that are required for our body's proper functioning. They are composed of different types of fatty acids, each with their own distinct chemical structure and properties.

· A diet high in saturated fat can negatively impact the structure and function of the brain by leading to a reduction in the size of the hippocampus, impairing learning and memory, increasing the risk of Alzheimer's disease, and contributing to inflammation in the body.

· Trans fats may negatively impact the structure and function of the brain by leading to a reduction in the size of the hippocampus, impairing learning and memory, increasing the risk of depression, and negatively affecting cognitive function

· Monounsaturated fats may positively affect the structure and function of the brain, leading to an increase in the size of the hippocampus, improving learning and memory, protecting against cognitive decline, and improving cognitive function.

· Polyunsaturated fats may positively affect the structure and function of the brain, with different effects seen for different types of polyunsaturated fats. Omega-3 fatty acids may improve learning and memory, as well as improve mood. Whilst essential in small doses, omega-6 fatty acids found in vegetable oils may impair learning and memory in higher amounts.



Fats are one of the essential nutrients that are required for our body's proper functioning. They are composed of different types of fatty acids, each with their own distinct chemical structure and properties. Fatty acids can be classified into saturated, monounsaturated, and polyunsaturated based on their degree of saturation. Trans fats are a specific type of unsaturated fat that has been artificially modified through a process called hydrogenation. In this article, I will discuss the impact of different types of fats on the structure and function of the brain.



Saturated Fats and the Brain



Saturated fats are typically found in animal products such as meat, dairy, and eggs. They are solid at room temperature and are known to increase LDL (low-density lipoprotein) cholesterol levels in the blood. High levels of LDL cholesterol have been linked to an increased risk of heart disease, but research has also highlighted the impact saturated fats can have on the brain.


A study conducted by Granholm (2008) found that a diet high in saturated fat led to structural changes in the hippocampus of rats, suggesting that a diet high in saturated fat may impair learning and memory. Additionally, Freeman and Granholm (2012) reported reduced integrity of the blood brain barrier and vascular damage in rats fed a diet high in saturated fats.


Another study conducted by Prasad et al. (2012) suggested that diets high in saturated fat may increase the risk of Alzheimer's disease. This is because a diet high in saturated fat can lead to the build-up of beta-amyloid plaques in the brain, which are a hallmark of Alzheimer's disease.


Saturated fat has also been shown to increase inflammation in the body, which can negatively impact the brain. Inflammation has been linked to a variety of brain disorders such as depression, anxiety, and schizophrenia (Miller et al., 2009).



Trans Fats and the Brain



Trans fats are typically found in processed foods such as fried foods, baked goods, and snack foods. They are known to increase LDL cholesterol levels and decrease HDL (high-density lipoprotein) cholesterol levels in the blood. Whilst these can have an effect on the cardiovascular system, recent research has also suggested that trans fats may negatively impact the structure and function of the brain.


Several studies have shown that a diet high in trans fats can lead to cognitive impairment and memory deficits (Kothari et al., 2016; Kothari et al., 2017; de Paula et al., 2021). A systematic review and meta-analysis of the literature by Taylor et al., (2021) found that trans fats impacted the integrity and function of the hippocampus in humans. This suggests that a diet high in trans fats may impair learning and memory, however, more research is needed to fully understand the extent and physiology of these changes.


Additionally, trans fats have been linked to an increased risk of depression (Lucas et al., 2014). Another study conducted by Issa et al. (2015) drew similar conclusions and proposed a link between depression and the propensity of trans fats to cause inflammation in the body, which has been linked to depression and other mental health disorders.


Trans fats have also been shown to negatively affect the cerebral cortex, which is responsible for conscious thought. A study conducted by Longhi et al. (2018) found that a diet high in trans fats led to a decrease in cognitive function in rats, which was a finding supported in a systematic review of the literature by Barnard, Bunner and Agarwal (2014). This suggests that a diet high in trans fats may impair the ability to think, reason, and remember.


Pase and Bürger (2019) address the fact that trans fatty acids can exert prolonged deleterious influences on functionality of the brain neural systems. They recognise that underlying mechanisms are still poorly understood but hypothesise that they may involve the incorporation of trans fatty acids into neuronal membranes, thus affecting their morphology, neurophysiology, and neurotransmission.



Monounsaturated Fats and the Brain



Monounsaturated fats, such as oleic acid, an omega 9 fatty acid, are a type of healthy fat found in plant-based sources such as nuts, seeds, and avocado. These fats are liquid at room temperature and have been linked to several health benefits, including improved heart health, as they are known to increase HDL cholesterol levels in the blood and decrease LDL cholesterol levels.


Recent research has suggested that monounsaturated fats may positively affect the structure and function of the brain. Bisogno et al. (2017) found that diets high in monounsaturated fats led to an increase in the size of the hippocampus in mice. This suggests that a diet high in monounsaturated fats may improve learning and memory.


A study conducted by Fekete et al. (2022) suggested that a diet high in monounsaturated fats may have a protective effect against cognitive decline in older adults. This is because monounsaturated fats have anti-inflammatory properties, which can help reduce inflammation in the brain that has been linked to cognitive decline.


Monounsaturated fats have also been shown to positively affect the cerebral cortex, which is responsible for conscious thought. A study conducted by Chappus-McCendie, H. et al., (2019) found that diets high in monounsaturated fats led to an improvement in cognitive function in adults with mild cognitive impairment.



Polyunsaturated Fats and the Brain



Polyunsaturated fats are also found in plant-based foods such as nuts, seeds, and vegetable oils. They are further classified into omega-3 and omega-6 fatty acids.

Omega-3 fatty acids are found in fatty fish such as salmon, mackerel, and sardines. They have been shown to have anti-inflammatory effects and may have a protective effect against cognitive decline (Dyall, 2015).


One study conducted by Witte et al. (2014) found that omega-3 fatty acid supplementation led to an increase in the size of the hippocampus in older adults. This suggests that omega-3 fatty acids may help improve learning and memory.

Another study conducted by Bauer et al. (2014) suggested that omega-3 fatty acids may help improve mood in individuals with depression. This is because omega-3 fatty acids have anti-inflammatory properties, which can help reduce inflammation in the brain that has been linked to depression and other mental health disorders.


Omega-6 fatty acids are found in vegetable oils such as corn, soybean, and sunflower oil. Although they are essential for the body, an excess of omega-6 fatty acids may lead to inflammation and increase the risk of chronic diseases such as heart disease (Simopoulos, 2002). While some studies have suggested that omega-6 fatty acids may have a positive effect on the brain, others have suggested that a diet high in omega-6 fatty acids may increase the risk of cognitive decline.


A study conducted by Cunnane et al. (2012) suggested that a diet high in omega-6 fatty acids may lead to a decrease in the size of the hippocampus in older adults. This suggests that a diet high in omega-6 fatty acids may impair learning and memory.



Conclusion



In conclusion, the type of fat we consume can have a significant impact on the structure and function of our brain. A diet high in saturated and trans fats may lead to cognitive impairment and memory deficits, while a diet high in monounsaturated and polyunsaturated fats may have a protective effect against cognitive decline. It is important to have a balanced diet that includes all types of fats in moderation to ensure optimal brain health.




REFERENCES & EVALUATION OF SCIENTIFIC POWER


Azam, S., Haque, M.E., Balakrishnan, R., Kim, I.S. and Choi, D.K., 2021. The ageing brain: molecular and cellular basis of neurodegeneration. Frontiers in Cell and Developmental Biology, 9, p.683459.


OVERVIEW: This article discusses the molecular and cellular mechanisms involved in neurodegeneration, which is the progressive loss of neuronal structure and function that is associated with aging and diseases such as Alzheimer's and Parkinson's. The authors provide an overview of the aging process and its effects on the brain, including the accumulation of toxic proteins and the decline in cellular function. They also discuss the role of oxidative stress and inflammation in neurodegeneration, as well as potential therapeutic targets for treating these conditions.

STRENGTHS: The article provides a comprehensive overview of the current understanding of the molecular and cellular mechanisms involved in neurodegeneration. The authors cite numerous high-quality scientific studies to support their arguments and provide detailed explanations of the complex processes involved. The article is well-written and accessible, making it a useful resource for students and researchers alike.

LIMITATIONS: While the article provides a thorough review of the literature, it does not present any new data or experiments. Additionally, some of the concepts discussed may be difficult for readers without a background in neuroscience or molecular biology to fully grasp.

SCIENTIFIC POWER: MODERATE to STRONG - The article is based on a thorough review of the scientific literature and cites numerous high-quality studies. However, it does not present any new data or experiments.



Barnard, N.D., Bunner, A.E. and Agarwal, U., 2014. Saturated and trans fats and dementia: a systematic review. Neurobiology of Aging, 35, pp.S65-S73.


OVERVIEW: This article is a systematic review of the literature on the relationship between saturated and trans fats and dementia. The authors examine studies that have investigated the association between consumption of these types of fats and the risk of developing dementia, as well as the mechanisms by which these fats may contribute to cognitive decline.

STRENGTHS: The article provides a comprehensive review of the literature on the topic, including studies with large sample sizes and longitudinal designs. The authors present clear and concise summaries of each study's findings and use meta-analytic techniques to synthesise the results. The article also discusses potential mechanisms by which saturated and trans fats may contribute to dementia.

LIMITATIONS: The article's focus on observational studies means that it cannot establish causality between fat consumption and dementia risk. Additionally, the article does not address other factors that may be associated with both fat consumption and dementia risk, such as physical activity or other aspects of diet.

SCIENTIFIC POWER: MODERATE - While the article provides a thorough review of the existing literature, its reliance on observational studies means that it cannot establish causality between fat consumption and dementia risk.



Bauer, I., Crewther, S., Pipingas, A., Sellick, L. and Crewther, D., 2014. Does omega‐3 fatty acid supplementation enhance neural efficiency? A review of the literature. Human Psychopharmacology: Clinical and Experimental, 29(1), pp.8-18.


OVERVIEW: This article reviews existing studies to investigate whether omega-3 fatty acid supplements can improve neural efficiency, which is the brain's ability to perform cognitive tasks with less effort. The review aims to identify the potential benefits of omega-3 supplementation in healthy adults and the mechanisms behind it.

STRENGTHS: The article thoroughly examines previous studies on the topic, highlighting the methods and results of each one. The authors explain the mechanisms through which omega-3 fatty acids may affect neural efficiency, such as reducing inflammation and oxidative stress. The article also suggests avenues for future research.

LIMITATIONS: The review does not provide a comprehensive analysis of all the studies on omega-3 fatty acid supplementation and neural efficiency. The authors note that some studies have shown no effect of omega-3 supplementation on cognitive performance or brain function.

SCIENTIFIC POWER: STRONG – It reviews multiple studies and discusses the mechanisms behind the effects of omega-3 fatty acids on neural efficiency. However, the limitations of the review indicate that further research is necessary to draw stronger conclusions about the relationship between omega-3 supplementation and neural efficiency.



Bauer, I., Hughes, M., Rowsell, R., Cockerell, R., Pipingas, A., Crewther, S. and Crewther, D., 2014. Omega‐3 supplementation improves cognition and modifies brain activation in young adults. Human Psychopharmacology: Clinical and Experimental, 29(2), pp.133-144.


OVERVIEW: This study investigates the effects of omega-3 fatty acid supplementation on cognitive performance and brain function in young adults. The authors hypothesise that omega-3 supplementation may improve cognitive function and modulate brain activation patterns in response to cognitive tasks.

STRENGTHS: The study is randomised and placebo-controlled, which strengthens the validity of the findings. The authors measure cognitive performance using standardised tests and also examine changes in brain activation patterns using functional MRI. The study includes a large sample size of 61 participants and a four-month intervention period.

LIMITATIONS: The study only examines the effects of omega-3 supplementation in young adults, so the findings cannot be generalised to other age groups. The study does not investigate the long-term effects of omega-3 supplementation on cognitive function and brain function.

SCIENTIFIC POWER: MODERATE to STRONG - It is a randomised, placebo-controlled study with a large sample size and rigorous methods. The study's limitations do not significantly detract from the strength of its findings, and the results provide valuable insight into the potential cognitive benefits of omega-3 fatty acid supplementation in young adults.



Bos, D.J., van Montfort, S.J., Oranje, B., Durston, S. and Smeets, P.A., 2016. Effects of omega-3 polyunsaturated fatty acids on human brain morphology and function: what is the evidence?. European Neuropsychopharmacology, 26(3), pp.546-561.


OVERVIEW: This article examines the effects of omega-3 polyunsaturated fatty acids (PUFAs) on the structure and function of the human brain. The authors review a large body of literature investigating the potential benefits of omega-3 PUFAs in improving brain health, including reducing the risk of neurodegenerative diseases and improving cognitive function.

STRENGTHS: The article provides a comprehensive and detailed overview of the existing literature on omega-3 PUFAs and brain health and highlights the strengths and limitations of various studies. The authors also provide a critical analysis of the evidence, discussing the implications of the findings for clinical practice and future research.

LIMITATIONS: While the authors provide a thorough review of the literature, there is a lack of experimental data or original research included in the article. Additionally, the authors note that there are still many unanswered questions regarding the optimal dose, duration, and form of omega-3 PUFA supplementation for brain health.

SCIENTIFIC POWER: MODERATE to STRONG - The article is based on a comprehensive review of the literature and draws on a large number of studies with a variety of research designs, including randomised controlled trials and cross-sectional studies.



Businaro, R., Corsi, M., Asprino, R., Di Lorenzo, C., Laskin, D., Corbo, R.M., Ricci, S. and Pinto, A., 2018. Modulation of inflammation as a way of delaying Alzheimer's disease progression: the diet's role. Current Alzheimer Research, 15(4), pp.363-380.


OVERVIEW: This article focuses on the role of inflammation in the development and progression of Alzheimer's disease and the potential for dietary interventions to modulate this process. The authors review a range of studies investigating the impact of various dietary factors, including omega-3 PUFAs, on inflammation and Alzheimer's disease.

STRENGTHS: The article provides a clear and detailed overview of the complex mechanisms underlying inflammation in Alzheimer's disease and the potential for dietary interventions to modulate this process. The authors also discuss the limitations of current research and highlight the need for further studies to clarify the role of dietary factors in Alzheimer's disease prevention and treatment.

LIMITATIONS: While the authors provide a comprehensive review of the literature, there is a lack of original research included in the article. Additionally, the authors note that the current evidence base is largely based on observational studies, which limit the ability to draw causal conclusions about the relationship between dietary factors and Alzheimer's disease.

SCIENTIFIC POWER: MODERATE - The article draws on a range of studies investigating the impact of dietary factors on inflammation and Alzheimer's disease, but largely relies on observational studies with limited ability to establish causality.



Carta, G., Murru, E., Banni, S. and Manca, C., 2017. Palmitic acid: physiological role, metabolism and nutritional implications. Frontiers in Physiology, 8, p.902.


OVERVIEW: This review article discusses palmitic acid, a type of saturated fatty acid, and its physiological role, metabolism, and nutritional implications. The article provides an overview of the structure and functions of palmitic acid in the body, as well as its potential health effects when consumed in excess.

STRENGTHS: The article presents a comprehensive review of the current knowledge on palmitic acid, including its metabolism and physiological functions. It also highlights the potential health effects of consuming high levels of palmitic acid, including an increased risk of cardiovascular disease and type 2 diabetes.

LIMITATIONS: The article does not provide a detailed analysis of the research methods used to study palmitic acid, nor does it include a critical evaluation of the quality of the evidence presented.

SCIENTIFIC POWER: STRONG - The article cites a large number of high-quality scientific studies and provides a thorough and accurate summary of the current state of knowledge on palmitic acid.



Chambergo-Michilot, D., Branez-Condorena, A., Falvy-Bockos, I., Pacheco-Mendoza, J. and Benites-Zapata, V.A., 2021. Efficacy of omega-3 supplementation on sertraline continuous therapy to reduce depression or anxiety symptoms: A systematic review and meta-analysis. Psychiatry Research, 296, p.113652.


OVERVIEW: This systematic review and meta-analysis evaluates the efficacy of omega-3 fatty acid supplementation in reducing depression and anxiety symptoms in individuals on continuous sertraline therapy. The article provides an overview of the relevant literature and summarizes the results of several clinical trials.

STRENGTHS: The article uses a systematic and comprehensive approach to evaluate the available evidence on the effectiveness of omega-3 fatty acid supplementation in reducing depression and anxiety symptoms. The authors provide a detailed analysis of the studies included in the review and present the results in a clear and concise manner.

LIMITATIONS: The studies included in the review have some heterogeneity in terms of their design, sample size, and outcome measures, which limits the ability to draw definitive conclusions. Additionally, the authors do not provide a detailed analysis of potential confounding factors, such as age, gender, and lifestyle factors.

SCIENTIFIC POWER: MODERATE to STRONG - The article cites a range of studies and employs a rigorous systematic review and meta-analysis methodology. However, the heterogeneity of the studies included in the review limits the strength of the conclusions that can be drawn.



Chappus-McCendie, H., Chevalier, L., Roberge, C. and Plourde, M., 2019. Omega-3 PUFA metabolism and brain modifications during aging. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 94, p.109662.


OVERVIEW: The article reviews the literature on how omega-3 polyunsaturated fatty acids (PUFAs) affect brain function during aging. The article explores the potential impact of omega-3 PUFAs on cognitive decline and age-related neurological disorders. The authors aim to provide an understanding of how omega-3 PUFAs can be used to promote healthy brain aging.

STRENGTHS: The review includes a comprehensive evaluation of numerous studies examining the impact of omega-3 PUFAs on brain function during aging. The authors provide detailed information on the molecular and cellular mechanisms underlying the effects of omega-3 PUFAs on brain function. The article highlights the potential of omega-3 PUFAs to prevent cognitive decline and age-related neurological disorders. The review also discusses the role of omega-3 PUFAs in promoting healthy brain aging.

LIMITATIONS: While the review covers a large body of literature, it could have been more balanced by including potential negative effects of omega-3 PUFA intake on brain health. Additionally, the review does not provide an in-depth analysis of some of the key mechanisms underlying the effects of omega-3 PUFAs on the brain during aging.

SCIENTIFIC POWER: MODERATE to STRONG - The review provides a good overview of the current research on omega-3 PUFAs and brain function during aging. However, there is a lack of in-depth analysis on some key mechanisms and potential negative effects of omega-3 PUFA intake on brain health.



Chianese, R., Coccurello, R., Viggiano, A., Scafuro, M., Fiore, M., Coppola, G., Operto, F.F., Fasano, S., Laye, S., Pierantoni, R. and Meccariello, R., 2018. Impact of dietary fats on brain functions. Current Neuropharmacology, 16(7), pp.1059-1085.


OVERVIEW: The article reviews the literature on how different types of dietary fats affect brain function. The article explores the potential impact of saturated, monounsaturated, and polyunsaturated fatty acids on cognitive function and behaviour. The authors aim to provide an understanding of how dietary fat intake affects brain health and neurological disorders.

STRENGTHS: The review includes a comprehensive evaluation of numerous studies examining the impact of different dietary fats on the brain. The authors provide detailed information on the molecular and cellular mechanisms underlying the effects of fatty acids on brain function. The article highlights the importance of essential omega-3 fatty acids in brain function and development. The review also discusses the role of dietary fats in the pathophysiology of neurological disorders such as Alzheimer's and Parkinson's disease.

LIMITATIONS: While the review covers a large body of literature, it could have been more balanced by including the potential negative effects of dietary fat intake on brain health. Additionally, the review does not provide an in-depth analysis of some of the key mechanisms underlying the effects of dietary fats on the brain.

SCIENTIFIC POWER: MODERATE to STRONG - The review provides a good overview of the current research on dietary fats and brain function. However, there is a lack of in-depth analysis on some key mechanisms and potential negative effects of dietary fat intake on brain health.



Cunnane, S.C., Schneider, J.A., Tangney, C., Tremblay-Mercier, J., Fortier, M., Bennett, D.A. and Morris, M.C., 2012. Plasma and brain fatty acid profiles in mild cognitive impairment and Alzheimer's disease. Journal of Alzheimer's Disease, 29(3), pp.691-697.


OVERVIEW: This study investigated the levels of fatty acids in the plasma and brain of individuals with mild cognitive impairment and Alzheimer's disease. The aim was to determine whether there are differences in the fatty acid profiles in these individuals compared to healthy individuals.

STRENGTHS: The study is well-designed, with a clear hypothesis and methodology. The use of both plasma and brain samples allows for a comprehensive analysis of fatty acid profiles.

LIMITATIONS: The sample size is relatively small, and the study is cross-sectional, meaning that it cannot establish causation. The study also only examined a limited number of fatty acids, so it is possible that other fatty acids could also play a role in cognitive decline.

SCIENTIFIC POWER: MODERATE to STRONG - While the sample size is small and the study is cross-sectional, the use of both plasma and brain samples and the well-designed methodology increase the scientific power of the study.



da Silva Batista, E., Nakandakari, S.C.B.R., Ramos da Silva, A.S., Pauli, J.R., Pereira de Moura, L., Ropelle, E.R., Camargo, E.A. and Cintra, D.E., 2022. Omega-3 pleiad: The multipoint anti-inflammatory strategy. Critical Reviews in Food Science and Nutrition, pp.1-16.


OVERVIEW: This review article discusses the potential anti-inflammatory effects of omega-3 fatty acids in various health conditions, including obesity, diabetes, and cardiovascular disease. The authors review the evidence from various studies and suggest that omega-3 fatty acids may be a useful strategy for reducing inflammation in these conditions.

STRENGTHS: The review provides a comprehensive overview of the research on the anti-inflammatory effects of omega-3 fatty acids, including both animal and human studies. The authors also discuss the potential mechanisms by which omega-3 fatty acids may exert their anti-inflammatory effects.

LIMITATIONS: The review is limited to studies investigating the anti-inflammatory effects of omega-3 fatty acids and does not examine other potential health benefits of these fatty acids. The review also does not include a meta-analysis of the studies, which could provide a more robust assessment of the evidence.

SCIENTIFIC POWER: MODERATE - While the review provides a thorough overview of the research, the lack of a meta-analysis and the focus on a specific aspect of omega-3 fatty acids limits its scientific power.



De Bem, A., Engel, D., de Oliveira, J., Moreira, E.L.G., Neis, V.B., Santos, D.B., Lopes, J.B., Rodrigues, A.L.S. and Brocardo, P., 2014. Hypercholesterolemia as a risk factor for depressive disorder? Free Radical Biology and Medicine, 75, p.S28.


OVERVIEW: The article explores the relationship between high levels of cholesterol and depression. It discusses how cholesterol can influence brain function, specifically by impairing the activity of certain enzymes that are important for mood regulation.

STRENGTHS: The article is based on a review of existing research, which means that the authors have considered a wide range of studies and findings. They provide a thorough analysis of the evidence and make some interesting observations about the link between cholesterol and depression.

LIMITATIONS: Although the authors provide a comprehensive overview of the research, they do not present any new data or conduct any experiments themselves. This means that the article is limited in terms of its original contributions to the field.

SCIENTIFIC POWER: MODERATE - It is a review of existing research rather than new data. However, the authors' extensive analysis of the existing literature makes a valuable contribution to our understanding of the relationship between cholesterol and depression.



de Oliveira, J., Engel, D.F., de Paula, G.C., Dos Santos, D.B., Lopes, J.B., Farina, M., Moreira, E.L. and de Bem, A.F., 2020. High cholesterol diet exacerbates blood-brain barrier disruption in LDLr–/–mice: impact on cognitive function. Journal of Alzheimer's Disease, 78(1), pp.97-115.


OVERVIEW: The article investigates the impact of a high-cholesterol diet on cognitive function and blood-brain barrier integrity in mice. The authors hypothesise that a diet high in cholesterol will exacerbate blood-brain barrier disruption, which can contribute to cognitive impairment.

STRENGTHS: The study provides original data and makes a significant contribution to our understanding of how a high-cholesterol diet can impact brain function. The authors use a well-established animal model and conduct a range of experiments to investigate the effects of the diet on cognitive function and blood-brain barrier integrity.

LIMITATIONS: The study is conducted on mice, so it is unclear whether the findings will generalise to humans. Additionally, the study only investigates the effects of a high-cholesterol diet, so it is unclear how other factors, such as exercise or medication, might interact with cholesterol to impact brain function.

SCIENTIFIC POWER: MODERATE to STRONG - The study provides original data, and the authors use a range of methods to investigate the impact of a high-cholesterol diet on cognitive function and blood-brain barrier integrity. However, the study is limited by its use of animal models, and it is unclear how the findings will generalise to humans.



de Paula, G.C., Brunetta, H.S., Engel, D.F., Gaspar, J.M., Velloso, L.A., Engblom, D., de Oliveira, J. and de Bem, A.F., 2021. Hippocampal function is impaired by a short-term high-fat diet in mice: Increased blood–brain barrier permeability and neuroinflammation as triggering events. Frontiers in Neuroscience, 15, p.734158.


OVERVIEW: The article examines the effects of a high-fat diet on the hippocampal function, which is an important brain region for learning and memory. The study was conducted in mice, where the researchers fed them with a high-fat diet for a short period and then evaluated their cognitive function. The study investigated the mechanisms that cause the cognitive decline in response to a high-fat diet, such as blood-brain barrier permeability and neuroinflammation.

STRENGTHS: The study provides new insights into the effects of a high-fat diet on hippocampal function and cognitive performance. The researchers used a mouse model to demonstrate that a high-fat diet can lead to cognitive impairment through increased blood-brain barrier permeability and neuroinflammation.

LIMITATIONS: The study was conducted on mice, and therefore the results may not be directly applicable to humans. Additionally, the short-term high-fat diet may not represent the long-term effects of a high-fat diet on the brain.

SCIENTIFIC POWER: MODERATE to STRONG - The research methods were carefully designed to investigate the specific mechanisms involved in the cognitive decline observed in response to a high-fat diet. However, the study's limitation in terms of generalisability to humans and the short duration of the high-fat diet intervention may slightly reduce the scientific power.



Derbyshire, E., 2018. Brain health across the lifespan: a systematic review on the role of omega-3 fatty acid supplements. Nutrients, 10(8), p.1094.


OVERVIEW: The article is a systematic review that examines the role of omega-3 fatty acid supplements in brain health across the lifespan. The study investigates the relationship between omega-3 fatty acid supplementation and cognitive function, memory, and mental health.

STRENGTHS: The study provides a comprehensive review of the available evidence on the effects of omega-3 fatty acid supplements on brain health. The systematic review method used in the study is a rigorous approach that aims to provide an objective and unbiased summary of the current evidence.

LIMITATIONS: The study only examines the effects of omega-3 fatty acid supplementation on brain health and does not take into account other factors that may contribute to cognitive decline, such as lifestyle and diet. Additionally, the study relies on the available evidence, which may vary in quality and may not be directly comparable.

SCIENTIFIC POWER: MODERATE to STRONG - The systematic review method is a rigorous approach to summarising evidence, but the quality of the available evidence may vary, which may affect the overall conclusions of the review. Additionally, the study only examines the effects of omega-3 fatty acid supplementation on brain health, and therefore, the results may not be generalisable to other factors that contribute to cognitive decline.



Djuricic, I. and Calder, P.C., 2021. Beneficial outcomes of omega-6 and omega-3 polyunsaturated fatty acids on human health: An update for 2021. Nutrients, 13(7), p.2421.


OVERVIEW: The article discusses the health benefits of omega-6 and omega-3 fatty acids. The article covers the functions of these fatty acids in the human body, their roles in different physiological processes, and their potential therapeutic benefits.

STRENGTHS: The article provides a comprehensive overview of the latest research on the health benefits of omega-6 and omega-3 fatty acids. It covers a wide range of topics, including cardiovascular health, inflammation, cognitive function, and mental health. The authors have cited several recent studies to support their arguments and have provided a clear and concise summary of the current state of research in this field.

LIMITATIONS: The article focuses on the benefits of omega-6 and omega-3 fatty acids and does not cover any potential negative effects of consuming these fats. It also does not provide specific recommendations for the optimal intake of these fatty acids.

SCIENTIFIC POWER: MODERATE to STRONG - The authors have cited several recent studies to support their arguments, but the article does not provide a detailed analysis of the methodology used in these studies. Additionally, the authors do not provide any specific recommendations for the optimal intake of omega-6 and omega-3 fatty acids.



Dyall, S.C., 2015. Long-chain omega-3 fatty acids and the brain: a review of the independent and shared effects of EPA, DPA and DHA. Frontiers in Aging Neuroscience, 7, p.52.


OVERVIEW: The article provides an overview of the latest research on the effects of long-chain omega-3 fatty acids on brain function. The article covers the roles of EPA, DPA, and DHA in different physiological processes, their effects on brain development and function, and their potential therapeutic benefits.

STRENGTHS: The article provides a detailed overview of the latest research on the effects of long-chain omega-3 fatty acids on brain function. It covers a wide range of topics, including neuroinflammation, neuroplasticity, and cognitive function. The authors have cited several recent studies to support their arguments and have provided a clear and concise summary of the current state of research in this field.

LIMITATIONS: The article focuses specifically on the effects of EPA, DPA, and DHA and does not cover any potential negative effects of consuming these fatty acids. It also does not provide specific recommendations for the optimal intake of these fatty acids.

SCIENTIFIC POWER: STRONG - The authors have cited several recent studies to support their arguments, and the article provides a detailed analysis of the methodology used in these studies. Additionally, the authors provide a clear and concise summary of the current state of research in this field.



Ellulu, M.S., Khaza’ai, H., Abed, Y., Rahmat, A., Ismail, P. and Ranneh, Y., 2015. Role of fish oil in human health and possible mechanism to reduce the inflammation. Inflammopharmacology, 23, pp.79-89.


OVERVIEW: This article discusses the role of fish oil in human health and how it may help reduce inflammation. It explains what fish oil is and the different types of omega-3 fatty acids found in it. It also discusses how inflammation can lead to chronic diseases such as heart disease and cancer. The article explores the potential mechanisms through which fish oil can reduce inflammation, such as by decreasing the production of pro-inflammatory molecules.

STRENGTHS: The article provides a clear and concise explanation of the benefits of fish oil on human health. It offers evidence-based explanations of the mechanisms through which omega-3 fatty acids in fish oil may reduce inflammation, and how this can benefit overall health.

LIMITATIONS: The article does not offer specific data or studies to support its claims, but instead offers a general overview of the potential benefits of fish oil. Therefore, further research would be required to establish the specific mechanisms of action of fish oil in reducing inflammation.

SCIENTIFIC POWER: MODERATE - The article provides a good overview of the role of fish oil in human health but lacks in-depth scientific studies to support its claims. However, the potential benefits of fish oil on reducing inflammation are well established in the scientific literature.



Engel, D.F., de Oliveira, J., Lopes, J.B., Santos, D.B., Moreira, E.L.G., Farina, M., Rodrigues, A.L.S., de Souza Brocardo, P. and de Bem, A.F., 2016. Is there an association between hypercholesterolemia and depression? Behavioural evidence from the LDLr−/− mouse experimental model. Behavioural Brain Research, 311, pp.31-38.


OVERVIEW: This article explores whether there is an association between hypercholesterolemia and depression using a mouse experimental model. The study examines the behaviour of LDLr−/− mice, which have high cholesterol levels, and compares it to that of wild-type mice. The article investigates whether the high cholesterol levels in LDLr−/− mice lead to depressive-like behaviours.

STRENGTHS: The article offers a detailed analysis of the behaviour of LDLr−/− mice, and how it compares to wild-type mice. It examines the potential association between hypercholesterolemia and depression, which is a novel topic in the field of neuroscience. The study is well designed, and the authors use established behavioural tests to assess the depressive-like behaviour of the mice.

LIMITATIONS: The study is conducted using animal models, and therefore its findings cannot be directly applied to humans. Additionally, the study only examines the behaviour of male mice, which may not be representative of the entire population.

SCIENTIFIC POWER: MODERATE to STRONG - The study offers valuable insights into the potential link between hypercholesterolemia and depression. However, the results cannot be generalised to humans and further research would be required to establish a causal link between high cholesterol levels and depressive-like behaviour.



Fekete, M., Szarvas, Z., Fazekas-Pongor, V., Feher, A., Csipo, T., Forrai, J., Dosa, N., Peterfi, A., Lehoczki, A., Tarantini, S. and Varga, J.T., 2022. Nutrition Strategies Promoting Healthy Aging: From Improvement of Cardiovascular and Brain Health to Prevention of Age-Associated Diseases. Nutrients, 15(1), p.47.


OVERVIEW: This article provides an overview of nutrition strategies that can promote healthy aging, with a focus on how these strategies can improve cardiovascular and brain health and prevent age-associated diseases. The authors explore the role of specific nutrients and dietary patterns, such as the Mediterranean diet, in promoting healthy aging. They also discuss the importance of physical activity, sleep, and stress reduction in maintaining health as we age.

STRENGTHS: This article provides a comprehensive overview of the role of nutrition in healthy aging, drawing on a wide range of scientific literature. The authors make a compelling case for the importance of dietary patterns and specific nutrients in promoting healthy aging and provide practical advice for implementing these strategies in daily life.

LIMITATIONS: While this article provides a thorough overview of the topic, it does not provide original research findings or data. Instead, it synthesises existing research in the field to provide a broad perspective on the topic.

SCIENTIFIC POWER: MODERATE to STRONG - The authors draw on a wide range of scientific literature to support their arguments, and their recommendations are consistent with current research in the field. However, as a review article, this paper does not present new research findings.



Freeman, L.R. and Granholm, A.C.E., 2012. Vascular changes in rat hippocampus following a high saturated fat and cholesterol diet. Journal of Cerebral Blood Flow & Metabolism, 32(4), pp.643-653.


OVERVIEW: This article investigates the effects of a high saturated fat and cholesterol diet on the blood vessels in the rat hippocampus, a brain region important for learning and memory. The authors hypothesised that this type of diet would lead to reduced blood flow and damage to the blood vessels in this region, which could contribute to cognitive impairment.

STRENGTHS: This study provides important insights into the effects of a high fat and cholesterol diet on the brain, and specifically on the blood vessels in the hippocampus. The authors use a well-established animal model to investigate these effects, and their findings suggest that this type of diet can indeed lead to vascular damage in the brain.

LIMITATIONS: This study was conducted on rats, so it is unclear whether these findings can be directly applied to humans. Additionally, the study only investigated the effects of a short-term high-fat diet, so it is unclear whether longer-term exposure to this type of diet would have different effects on the brain.

SCIENTIFIC POWER: MODERATE - The study provides important insights into the effects of a high-fat diet on the brain, but its generalisability to humans is limited by the fact that it was conducted on rats. Additionally, the study only investigated the effects of short-term exposure to a high-fat diet, so it is unclear how these findings would apply to longer-term exposure.



Granholm, A.C., Bimonte-Nelson, H.A., Moore, A.B., Nelson, M.E., Freeman, L.R. and Sambamurti, K., 2008. Effects of a saturated fat and high cholesterol diet on memory and hippocampal morphology in the middle-aged rat. Journal of Alzheimer's Disease, 14(2), pp.133-145.


OVERVIEW: Granholm et al. investigated the effects of a high saturated fat and high cholesterol diet on memory and brain structure in middle-aged rats. The authors fed one group of rats a high-fat diet and another group a control diet for 4 months, and then assessed their cognitive function and hippocampal morphology.

STRENGTHS: The study provides insights into how a high-fat diet can affect brain health and cognitive function. The authors used well-established methods to assess memory and hippocampal morphology, and their results suggest that the high-fat diet caused memory impairment and structural changes in the hippocampus of middle-aged rats.

LIMITATIONS: The study was conducted in rats, so it is unclear whether the findings can be applied to humans. Additionally, the study only investigated the effects of a high-fat diet in middle-aged rats, so it is unclear how the diet affects younger or older rats. Finally, the study did not investigate the mechanisms underlying the observed effects, so it is unclear how the high-fat diet causes memory impairment and structural changes in the hippocampus.

SCIENTIFIC POWER: MODERATE - The study used a relatively small sample size of rats, which limits the generalisability of the findings. Additionally, the study did not investigate the mechanisms underlying the observed effects, which limits the depth of the study.



Grant, R. and Guest, J., 2016. Role of omega-3 PUFAs in neurobiological health. The Benefits of Natural Products for Neurodegenerative Diseases, pp.247-274.


OVERVIEW: Grant and Guest reviewed the role of omega-3 polyunsaturated fatty acids (PUFAs) in neurobiological health. The authors discussed the mechanisms by which omega-3 PUFAs can affect brain function and how they may be beneficial in the prevention and treatment of neurodegenerative diseases.

STRENGTHS: The review provides a comprehensive overview of the current understanding of the role of omega-3 PUFAs in neurobiological health. The authors used a wide range of studies to support their arguments, including in vitro and in vivo studies as well as clinical trials. The review provides insights into how omega-3 PUFAs can affect brain function and the potential benefits of omega-3 PUFAs in the prevention and treatment of neurodegenerative diseases.

LIMITATIONS: The review focused primarily on the beneficial effects of omega-3 PUFAs, so it did not discuss the potential negative effects of omega-3 PUFAs or the optimal dosage of omega-3 PUFAs for brain health. Additionally, the review did not provide a systematic analysis of the studies it included, so it is unclear how robust the evidence is.

SCIENTIFIC POWER: MODERATE to STRONG - The review provides a comprehensive overview of the current understanding of the role of omega-3 PUFAs in neurobiological health, but it does not provide a systematic analysis of the studies it includes. Nonetheless, the review draws on a wide range of studies to support its arguments, including in vitro and in vivo studies as well as clinical trials.



Haast, R.A. and Kiliaan, A.J., 2015. Impact of fatty acids on brain circulation, structure and function. Prostaglandins, Leukotrienes and Essential Fatty Acids, 92, pp.3-14.


OVERVIEW: This review article discusses the impact of fatty acids on the circulation, structure, and function of the brain. The article focuses on the effects of different types of fatty acids on the brain, including omega-3 and omega-6 fatty acids. The review also examines the mechanisms by which fatty acids affect the brain, such as through their effects on cell membrane structure and function.

STRENGTHS: This review provides a comprehensive overview of the current understanding of the effects of fatty acids on the brain. The article covers a broad range of topics, including the role of fatty acids in the development of neurodegenerative diseases, such as Alzheimer's and Parkinson's. The authors provide a detailed analysis of the mechanisms by which different types of fatty acids affect the brain.

LIMITATIONS: While the review is comprehensive, it does not discuss the impact of specific diets or dietary supplements on brain function. Instead, the focus is on the effects of different types of fatty acids in general.

SCIENTIFIC POWER: MODERATE to STRONG - The article provides a thorough analysis of the current state of research on the impact of fatty acids on the brain. However, the article does not provide new empirical data or experiments, but rather synthesises existing research.



Hallahan, B., Ryan, T., Hibbeln, J.R., Murray, I.T., Glynn, S., Ramsden, C.E., SanGiovanni, J.P. and Davis, J.M., 2016. Efficacy of omega-3 highly unsaturated fatty acids in the treatment of depression. The British Journal of Psychiatry, 209(3), pp.192-201.


OVERVIEW: This study investigates the efficacy of omega-3 fatty acids in the treatment of depression. The article provides a summary of the current understanding of the role of omega-3 fatty acids in the brain and their potential therapeutic benefits for depression. The study also provides an analysis of the results of randomised controlled trials investigating the effects of omega-3 supplementation on depression.

STRENGTHS: This study provides a thorough analysis of the existing literature on the effects of omega-3 fatty acids on depression. The authors analyse data from several randomised controlled trials and provide a detailed summary of the findings. The study also provides insight into the potential mechanisms by which omega-3 fatty acids affect the brain and influence depression.

LIMITATIONS: One limitation of this study is that it only focuses on the effects of omega-3 fatty acids on depression and does not consider the potential effects of other dietary factors. Additionally, the authors note that the study is limited by the heterogeneity of the included trials.

SCIENTIFIC POWER: MODERATE - The study provides a thorough analysis of the existing literature on the effects of omega-3 fatty acids on depression. However, as the authors note, the heterogeneity of the included trials limits the strength of the conclusions that can be drawn. Additionally, the study does not provide new empirical data, but rather synthesises existing research.



Heneka, M.T., Carson, M.J., El Khoury, J., Landreth, G.E., Brosseron, F., Feinstein, D.L., Jacobs, A.H., Wyss-Coray, T., Vitorica, J., Ransohoff, R.M. and Herrup, K., 2015. Neuroinflammation in Alzheimer's disease. The Lancet Neurology, 14(4), pp.388-405.


OVERVIEW: This article discusses the role of neuroinflammation in Alzheimer's disease, which is the inflammation of the brain that occurs in response to damage, infection, or toxic compounds. It highlights the different types of immune cells that contribute to neuroinflammation and their effects on brain cells in Alzheimer's disease.

STRENGTHS: The article provides a comprehensive review of the current knowledge on neuroinflammation in Alzheimer's disease, covering various aspects such as the types of immune cells involved, the signalling pathways that regulate neuroinflammation, and the potential therapeutic targets for treating neuroinflammation. The authors have gathered evidence from numerous studies conducted over the years, making the article a reliable source of information.

LIMITATIONS: While the article provides an extensive overview of the role of neuroinflammation in Alzheimer's disease, it does not provide a clear understanding of the underlying mechanisms that lead to neuroinflammation. Furthermore, the article does not discuss the role of lifestyle factors such as diet and exercise in preventing or reducing neuroinflammation in Alzheimer's disease.

SCIENTIFIC POWER: STRONG - The article is based on a comprehensive review of the current literature on neuroinflammation in Alzheimer's disease. The authors have compiled and analysed evidence from numerous studies conducted over the years, making the article a reliable source of information for researchers and healthcare professionals in the field.


Jahangard, L., Hedayati, M., Abbasalipourkabir, R., Haghighi, M., Ahmadpanah, M., Faryadras, M., Mikoteit, T., Bahmani, D.S. and Brand, S., 2019. Omega-3-polyunsatured fatty acids (O3PUFAs), compared to placebo, reduced symptoms of occupational burnout and lowered morning cortisol secretion. Psychoneuroendocrinology, 109, p.104384.


OVERVIEW: Occupational burnout is a common condition among individuals who experience prolonged stress at work. This study investigates the effects of omega-3-polyunsaturated fatty acids (O3PUFAs) on occupational burnout symptoms and cortisol levels. O3PUFAs are essential fatty acids that are found in fish and other marine sources and are known to have anti-inflammatory and neuroprotective properties.

STRENGTHS: The study provides evidence of the potential benefits of O3PUFAs in reducing symptoms of occupational burnout and lowering cortisol levels. The study used a randomised, double-blind, placebo-controlled design, which is considered the gold standard in clinical research. The study also used validated questionnaires and laboratory assays to measure the outcomes, making the results reliable.

LIMITATIONS: The study was conducted on a relatively small sample size of 68 participants, and the duration of intervention was only four weeks. Therefore, the long-term effects of O3PUFAs on occupational burnout symptoms and cortisol levels remain unclear. The study also did not investigate the underlying mechanisms by which O3PUFAs may have reduced burnout symptoms and cortisol levels.

SCIENTIFIC POWER: MODERATE to STRONG - The study provides evidence of the potential benefits of O3PUFAs in reducing symptoms of occupational burnout.



Jensen, D.E., Leoni, V., Klein-Flügge, M.C., Ebmeier, K.P. and Suri, S., 2021. Associations of dietary markers with brain volume and connectivity: A systematic review of MRI studies. Ageing Research Reviews, 70, p.101360.


OVERVIEW: The article systematically reviews the literature on the associations between dietary markers and brain volume/connectivity using MRI studies. The authors aimed to determine the relationships between dietary markers, such as vitamins, minerals, and macronutrients, and brain structure/function in healthy and clinical populations.

STRENGTHS: The systematic review is a comprehensive and up-to-date analysis of the available literature on the relationship between diet and brain structure/function. The authors have used rigorous criteria to select studies and have performed a thorough analysis of the findings. The study provides valuable insights into the role of various dietary components in brain health.

LIMITATIONS: The studies reviewed in this article are observational, and therefore, causality cannot be established. Moreover, the studies included in this review varied significantly in terms of the dietary markers studied, study designs, and the populations studied. Hence, generalizing the findings is challenging.

SCIENTIFIC POWER: MODERATE - It is a systematic review of observational studies. Although the analysis is comprehensive, it cannot establish a causal relationship between dietary markers and brain structure/function.



Kothari, V., Tornabene, T., Luo, Y., Greene, M., Thangiah, G. and Jeganathan, R., 2016, June. High Fat Western Diet-induced Brain Insulin Resistance and Cognitive Impairment. In DIABETES (Vol. 65, pp. A498-A498). 1701 N BEAUREGARD ST, ALEXANDRIA, VA 22311-1717 USA: AMER DIABETES ASSOC.


OVERVIEW: The study investigates the impact of a high-fat Western diet on brain insulin resistance and cognitive impairment in rats. The authors aimed to determine whether a diet high in saturated fat and sugar, similar to the typical Western diet, induces cognitive impairment and brain insulin resistance.

STRENGTHS: The study is an experimental study that investigated the impact of a high-fat Western diet on brain insulin resistance and cognitive impairment. The authors used a well-established animal model to study the effects of the diet, which enhances the validity of the findings. The study provides valuable insights into the impact of a Western diet on brain health.

LIMITATIONS: The study was performed on rats, and therefore, the results cannot be directly extrapolated to humans. Moreover, the study only investigated the effects of a high-fat Western diet on brain insulin resistance and cognitive impairment, and the findings cannot be generalised to other dietary patterns.

SCIENTIFIC POWER: MODERATE - It is an experimental study conducted on an animal model. Although the study provides valuable insights into the effects of a high-fat Western diet on brain insulin resistance and cognitive impairment, the findings cannot be directly extrapolated to humans.



Kothari, V., Luo, Y., Tornabene, T., O'Neill, A.M., Greene, M.W., Geetha, T. and Babu, J.R., 2017. High fat diet induces brain insulin resistance and cognitive impairment in mice. Biochimica et Biophysica Acta (BBA)-Molecular Basis of Disease, 1863(2), pp.499-508.


OVERVIEW: The article examines the impact of a high-fat diet on brain insulin resistance and cognitive function in mice. The study finds that the high-fat diet leads to insulin resistance in the brain and reduced cognitive function.

STRENGTHS: The study was conducted in a controlled laboratory environment using mice. The study employed a well-established cognitive function test, the Morris water maze, to evaluate cognitive function. The study also used immunoblotting to measure insulin resistance in the brain.

LIMITATIONS: The study was conducted in mice, and it may not be possible to generalise the results to humans. The study does not explore the potential mechanisms underlying the development of insulin resistance in the brain.

SCIENTIFIC POWER: MODERATE - The study was conducted in a controlled laboratory environment and used well-established methods to evaluate cognitive function and insulin resistance. However, the study was limited by its use of mice and its failure to explore the mechanisms underlying insulin resistance in the brain.



La Rosa, F., Clerici, M., Ratto, D., Occhinegro, A., Licito, A., Romeo, M., Iorio, C.D. and Rossi, P., 2018. The gut-brain axis in Alzheimer’s disease and omega-3. A critical overview of clinical trials. Nutrients, 10(9), p.1267.


OVERVIEW: The article reviews the relationship between the gut-brain axis and Alzheimer’s disease, with a focus on the potential benefits of omega-3 supplementation. The review analyses various clinical trials that have investigated the effects of omega-3 on cognitive function and brain health in Alzheimer’s disease patients.

STRENGTHS: The article provides a comprehensive overview of the current research on the gut-brain axis and Alzheimer’s disease. The review analyses multiple clinical trials, providing readers with a thorough understanding of the effects of omega-3 supplementation on cognitive function and brain health in Alzheimer’s disease patients. Additionally, the article discusses the potential mechanisms by which omega-3 may benefit the gut-brain axis and provides suggestions for future research.

LIMITATIONS: One limitation of the article is that it only focuses on clinical trials, so it does not provide a comprehensive overview of all the research on the gut-brain axis and Alzheimer’s disease. Additionally, the article does not provide a meta-analysis or systematic review of the studies analysed, which could limit the strength of the conclusions drawn from the research.

SCIENTIFIC POWER: MODERATE - The article provides a thorough review of multiple clinical trials but does not provide a meta-analysis or systematic review of the studies analysed, which could limit the strength of the conclusions drawn from the research.



Leckie, R.L., Lehman, D.E., Gianaros, P.J., Erickson, K.I., Sereika, S.M., Kuan, D.C., Manuck, S.B., Ryan, C.M., Yao, J.K. and Muldoon, M.F., 2020. The effects of omega-3 fatty acids on neuropsychological functioning and brain morphology in mid-life adults: A randomised clinical trial. Psychological Medicine, 50(14), pp.2425-2434.


OVERVIEW: This study investigated whether taking omega-3 fatty acid supplements improved brain function and structure in middle-aged adults. Participants were randomly assigned to either take omega-3 supplements or a placebo for six months. Various neuropsychological tests and brain imaging were conducted before and after the intervention.

STRENGTHS: The study was a randomised clinical trial, which is a strong study design. The researchers used standardised neuropsychological tests and brain imaging techniques to assess brain function and structure. The study was also well-controlled, with both the omega-3 and placebo groups having similar characteristics at baseline.

LIMITATIONS: The study had a relatively small sample size, with only 84 participants. The study was also relatively short, with only a six-month intervention period. Additionally, the study did not measure the participants’ omega-3 levels before the intervention, which would have provided valuable information about the participants’ baseline omega-3 status.

SCIENTIFIC POWER: MODERATE - Overall, this study provides moderate evidence that omega-3 fatty acid supplements may improve brain function and structure in middle-aged adults. However, the study’s limitations, including its small sample size and short duration, suggest that further research is needed to confirm these findings.



Longhi, R., Almeida, R.F., Pettenuzzo, L.F., Souza, D.G., Machado, L., Quincozes-Santos, A. and Souza, D.O., 2018. Effect of a trans fatty acid-enriched diet on mitochondrial, inflammatory, and oxidative stress parameters in the cortex and hippocampus of Wistar rats. European Journal of Nutrition, 57, pp.1913-1924.


OVERVIEW: This study investigated the effects of a diet high in trans fatty acids on brain health in rats. Rats were fed either a diet high in trans fatty acids or a control diet for 12 weeks. The researchers measured various markers of brain health, including mitochondrial function, inflammation, and oxidative stress.

STRENGTHS: The study used a well-established animal model, and the researchers measured a variety of different markers of brain health. The study was also well-controlled, with the rats in both the trans fatty acid and control groups having similar characteristics at baseline.

LIMITATIONS: The study was conducted in rats, and it is unclear whether the results would apply to humans. Additionally, the study did not measure any behavioural outcomes, such as cognitive function or mood.

SCIENTIFIC POWER: MODERATE - Overall, this study provides low to moderate evidence that a diet high in trans fatty acids may have negative effects on brain health, including mitochondrial function, inflammation, and oxidative stress. However, the study’s limitations, including the fact that it was conducted in rats and did not measure any behavioural outcomes, suggest that further research is needed to confirm these findings and determine their relevance to human health.



Lucas, M., Chocano-Bedoya, P., Shulze, M.B., Mirzaei, F., O’Reilly, É.J., Okereke, O.I., Hu, F.B., Willett, W.C. and Ascherio, A., 2014. Inflammatory dietary pattern and risk of depression among women. Brain, Behaviour, and Immunity, 36, pp.46-53.


OVERVIEW: Lucas et al. (2014) conducted a study to investigate whether the inflammatory dietary pattern is associated with an increased risk of depression among women. The study examined the dietary pattern of 43,685 women and followed up with them for an average of 12 years. The researchers also assessed the participants' depressive symptoms during the study period.

STRENGTHS: The study is based on a large sample size, which increases its statistical power. The researchers adjusted for several potential confounding factors, such as age, smoking, and physical activity, which makes the study findings more reliable. The study also used validated instruments to assess the participants' dietary patterns and depressive symptoms, which increases the accuracy of the results.

LIMITATIONS: The study is limited by its observational design, which makes it difficult to establish a causal relationship between the inflammatory dietary pattern and depression. The study only included women, so the results may not be generalisable to men. Additionally, the dietary pattern was only assessed at baseline, and changes in dietary habits during the study period were not accounted for.

SCIENTIFIC POWER: MODERATE - It is an observational study, and it is difficult to establish a cause-and-effect relationship between the inflammatory dietary pattern and depression.



Macaron, T., Giudici, K.V., Bowman, G.L., Sinclair, A., Stephan, E., Vellas, B. and de Souto Barreto, P., 2021. Associations of Omega-3 fatty acids with brain morphology and volume in cognitively healthy older adults: A narrative review. Ageing Research Reviews, 67, p.101300.


OVERVIEW: Macaron et al. (2021) conducted a narrative review of studies investigating the association between omega-3 fatty acids and brain morphology in cognitively healthy older adults. The review included studies that examined the association between omega-3 fatty acids and brain volume, white matter integrity, and grey matter volume.

STRENGTHS: The study is based on a comprehensive review of existing studies, which provides a broad perspective on the topic. The study focused on cognitively healthy older adults, which increases the relevance of the findings to this population. The studies reviewed used validated methods to measure brain morphology, which increases the accuracy of the results.

LIMITATIONS: The review is limited by the heterogeneity of the studies included in the analysis, which makes it difficult to draw conclusive findings. The studies reviewed had varying doses, sources, and duration of omega-3 fatty acid supplementation, which may have contributed to the heterogeneity of the findings. The review did not include studies that investigated the effect of omega-3 fatty acids on cognitive functioning, which is an important outcome in this population.

SCIENTIFIC POWER: MODERATE to STRONG - It is a comprehensive review of existing studies, but the heterogeneity of the studies included in the analysis limits the strength of the conclusions that can be drawn.



Masana, M.F., Koyanagi, A., Haro, J.M. and Tyrovolas, S., 2017. n-3 Fatty acids, Mediterranean diet and cognitive function in normal aging: A systematic review. Experimental Gerontology, 91, pp.39-50.


OVERVIEW: This article is a systematic review that examines the relationship between n-3 fatty acids and cognitive function in normal aging. The authors reviewed 16 studies that involved 22,048 participants.

STRENGTHS: The study is a systematic review providing an overall picture of the research on this topic. The authors used a rigorous methodology to analyse the studies.

LIMITATIONS: The studies reviewed in this article had different methods for measuring cognitive function, which makes it difficult to compare the results across studies. The authors also noted that the studies had different populations and different dietary patterns, which could impact the results.

SCIENTIFIC POWER: MODERATE - The study is a systematic review, which is considered to be of high quality. However, the studies reviewed had variations in the methods for measuring cognitive function and different populations, which could impact the overall findings.



Miller, A.H., Maletic, V. and Raison, C.L., 2009. Inflammation and its discontents: the role of cytokines in the pathophysiology of major depression. Biological Psychiatry, 65(9), pp.732-741.


OVERVIEW: This article explores the role of cytokines in major depression. Cytokines are proteins that play an important role in the body's immune response to infection and injury. However, they can also contribute to inflammation and affect brain function, potentially leading to depression. The authors review studies that suggest that cytokines are associated with major depression and explain how cytokines can affect brain function and behaviour.

STRENGTHS: The article provides a comprehensive review of the literature on cytokines and depression, discussing both preclinical and clinical studies. The authors provide a detailed explanation of how cytokines can affect the brain and contribute to depression.

LIMITATIONS: While the article provides a thorough review of the literature, it does not discuss potential confounding factors that may influence the relationship between cytokines and depression. Additionally, the article focuses primarily on the role of pro-inflammatory cytokines in depression and does not discuss the role of anti-inflammatory cytokines.

SCIENTIFIC POWER: MODERATE - While the article provides a thorough review of the literature on cytokines and depression, it does not provide new empirical evidence. However, the authors draw upon a wide range of studies to support their arguments.



Miller, A.H. and Raison, C.L., 2016. The role of inflammation in depression: from evolutionary imperative to modern treatment target. Nature Reviews Immunology, 16(1), pp.22-34.


OVERVIEW: This article discusses the role of inflammation in depression. The authors argue that inflammation is an evolutionary response to infection that can have negative effects on mood and behaviour. The article reviews the evidence for a link between inflammation and depression and discusses the potential use of anti-inflammatory agents as a treatment for depression.

STRENGTHS: The article provides a comprehensive review of the literature on inflammation and depression, discussing both preclinical and clinical studies. The authors provide a detailed explanation of how inflammation can affect the brain and contribute to depression. Additionally, the article discusses potential treatment options for depression based on the relationship between inflammation and depression.

LIMITATIONS: While the article provides a thorough review of the literature, it does not discuss potential confounding factors that may influence the relationship between inflammation and depression. Additionally, the article focuses primarily on the role of pro-inflammatory cytokines in depression and does not discuss the role of anti-inflammatory cytokines.

SCIENTIFIC POWER: MODERATE to STRONG - While the article provides a thorough review of the literature on inflammation and depression, it does not provide new empirical evidence. However, the authors draw upon a wide range of studies to support their arguments and provide a compelling argument for the potential use of anti-inflammatory agents as a treatment for depression.



Muth, A.K. and Park, S.Q., 2021. The impact of dietary macronutrient intake on cognitive function and the brain. Clinical Nutrition, 40(6), pp.3999-4010.


OVERVIEW: This review article discusses the relationship between macronutrient intake and cognitive function in humans. Macronutrients are the three main types of nutrients found in food, namely carbohydrates, proteins, and fats. The authors reviewed various studies that have investigated the impact of macronutrient intake on cognitive function and brain health.

STRENGTHS: The article provides a comprehensive review of studies conducted on the relationship between macronutrient intake and cognitive function. The authors have discussed the findings of various studies in detail, which makes it easier for readers to understand the current state of knowledge in this field. The article is also well-structured and easy to read.

LIMITATIONS: The review mainly focuses on observational studies, which cannot establish causality. The authors have also highlighted the heterogeneity of the studies, which makes it difficult to draw definitive conclusions.

SCIENTIFIC POWER: MODERATE - The article is a review of studies conducted in humans and provides a good overview of the current state of knowledge on the topic. However, most studies were observational, limiting the strength of the conclusions that can be drawn.



Obomsawin, A., D’Amico, D. and Fiocco, A.J., 2022. The association between Mediterranean diet adherence and allostatic load in older adults. Psychoneuroendocrinology, 143, p.105840.


OVERVIEW: This article investigates the relationship between adherence to the Mediterranean diet and allostatic load in older adults. Allostatic load refers to the wear and tear on the body that accumulates as a result of chronic stress. The Mediterranean diet is a dietary pattern that is rich in fruits, vegetables, whole grains, and healthy fats.

STRENGTHS: The study provides novel information on the potential impact of the Mediterranean diet on allostatic load in older adults. The authors used a well-established measurement tool to assess adherence to the Mediterranean diet, and the study was conducted in a large sample of older adults. The authors also controlled for various confounding variables.

LIMITATIONS: The study is cross-sectional, which means that it cannot establish causality. It is also limited by the use of self-reported data, which may be subject to recall bias.

SCIENTIFIC POWER: MODERATE - The study provides novel insights into the potential impact of the Mediterranean diet on allostatic load in older adults. However, it is limited by its cross-sectional design and the use of self-reported data.



Pase, C.S. and Bürger, M.E., 2019. Trans Fat Intake and Behaviour. In The Molecular Nutrition of Fats (pp. 189-197). Academic Press.


OVERVIEW: The review article investigates the relationship between trans fats intake and behaviour. Trans fats are known to be harmful to health, but their effect on behaviour is less clear. The authors examined studies that investigated the effects of trans fats on cognitive function, mood, and aggression.

STRENGTHS: The authors carefully searched and reviewed relevant studies in the field, which strengthens the credibility of their findings. The review provides a comprehensive summary of the current knowledge on the topic and highlights the need for further research to fully understand the impact of trans fats on behaviour.

LIMITATIONS: The review article does not present any new research, but instead synthesises the existing literature. The studies reviewed varied in methodology, sample size, and outcome measures, which limits the generalisability of the findings. Additionally, some studies included in the review relied on self-report measures, which can be subject to biases and inaccuracies.

SCIENTIFIC POWER: MODERATE - While the review article is informative and well-structured, it does not provide novel data, and the variability of the studies reviewed limits the strength of the conclusions. However, the article highlights the importance of reducing trans fats intake for overall health and underscores the need for more research on their impact on behaviour.



Perez, S.D., Du, K., Rendeiro, C., Wang, L., Wu, Q., Rubakhin, S.S., Vazhappilly, R., Baxter, J.H., Sweedler, J.V. and Rhodes, J.S., 2017. A unique combination of micronutrients rejuvenates cognitive performance in aged mice. Behavioural Brain Research, 320, pp.97-112.


OVERVIEW: The study investigated the effects of a unique combination of micronutrients on cognitive performance in aged mice. The authors hypothesised that the micronutrients would improve cognitive function, and they used a battery of tests to assess learning, memory, and attention.

STRENGTHS: The study employed a rigorous experimental design with a large sample size and a control group. The authors used a battery of tests to evaluate cognitive function, which enhances the reliability and validity of the findings. Additionally, the study explored the underlying mechanisms by examining the levels of specific neurotransmitters in the brain.

LIMITATIONS: The study was conducted on mice, which limits the generalisability of the findings to humans. Additionally, the study only investigated the short-term effects of the micronutrient combination, and it is unclear whether the effects are sustained over longer periods.

SCIENTIFIC POWER: MODERATE to STRONG - The study provides compelling evidence that a unique combination of micronutrients can improve cognitive function in aged mice. However, more research is needed to confirm the findings in humans and to determine the long-term effects of the micronutrient combination. Overall, the study provides valuable insights into the potential benefits of dietary interventions for cognitive health.



Prasad, S., Sung, B. and Aggarwal, B.B., 2012. Age-associated chronic diseases require age-old medicine: role of chronic inflammation. Preventive Medicine, 54, pp.S29-S37.


OVERVIEW: Chronic inflammation has been linked to several age-associated chronic diseases such as cancer, cardiovascular disease, and diabetes. In this article, the authors review the role of chronic inflammation in the development of these diseases and discuss the potential benefits of using natural remedies, such as spices and herbs, to combat chronic inflammation.

STRENGTHS: The authors provide a comprehensive overview of the role of chronic inflammation in the pathogenesis of age-associated chronic diseases. They also discuss the potential benefits of using natural remedies to combat chronic inflammation.

LIMITATIONS: The article focuses on the potential benefits of using natural remedies but does not provide specific recommendations or guidelines for their use. Additionally, the article does not discuss potential risks associated with the use of natural remedies.

SCIENTIFIC POWER: MODERATE - While the article provides a good overview of the topic, it lacks specific recommendations and guidelines, which limits its practical applicability. The authors also do not provide any new research findings, but rather summarise existing research.



Rangel-Huerta, O.D. and Gil, A., 2018. Effect of omega-3 fatty acids on cognition: an updated systematic review of randomised clinical trials. Nutrition Reviews, 76(1), pp.1-20.


OVERVIEW: This article is a systematic review that looks at the effects of omega-3 fatty acids on cognitive function in randomised clinical trials. The authors reviewed 19 studies that involved 1,980 participants.

STRENGTHS: The study is a systematic review providing an overall picture of the research on this topic. The studies reviewed in this article were randomised clinical trials, which are considered the gold standard in scientific research. The authors also used a rigorous methodology to analyse the studies.

LIMITATIONS: The studies reviewed in this article had different doses of omega-3 fatty acids and different durations, which makes it difficult to compare the results across studies. The authors also noted that there were variations in the cognitive tests used in the studies, which could impact the results.

SCIENTIFIC POWER: MODERATE to STRONG - The study is a systematic review of randomised clinical trials, which are considered to be of high quality. However, the studies reviewed had variations in dose and duration, which could impact the overall findings.



Simopoulos, A.P., 2002. Omega-3 fatty acids in inflammation and autoimmune diseases. Journal of the American College of Nutrition, 21(6), pp.495-505.


OVERVIEW: This article explores the role of omega-3 fatty acids in inflammation and autoimmune diseases. The author discusses the anti-inflammatory effects of omega-3 fatty acids and their potential role in the prevention and treatment of autoimmune diseases.

STRENGTHS: The author provides a comprehensive overview of the anti-inflammatory effects of omega-3 fatty acids and the potential benefits of their use in the prevention and treatment of autoimmune diseases. The article is also well-referenced, providing readers with a solid foundation for further research.

LIMITATIONS: The article focuses primarily on the anti-inflammatory effects of omega-3 fatty acids and does not discuss potential risks associated with their use. Additionally, the article does not provide specific recommendations or guidelines for the use of omega-3 fatty acids in the prevention or treatment of autoimmune diseases.

SCIENTIFIC POWER: MODERATE to STRONG - The article provides a good overview of the topic and is well-referenced but lacks specific recommendations or guidelines for the practical application of the research. Additionally, the article does not provide any new research findings, but rather summarises existing research.



Taylor, Z.B., Stevenson, R.J., Ehrenfeld, L. and Francis, H.M., 2021. The impact of saturated fat, added sugar and their combination on human hippocampal integrity and function: A systematic review and meta-analysis. Neuroscience & Biobehavioural Reviews, 130, pp.91-106.


OVERVIEW: This article is a systematic review and meta-analysis that investigated the effect of saturated fat and added sugar on the hippocampal integrity and function in humans. The hippocampus is a region of the brain that is involved in memory and learning. The authors reviewed 16 studies and found that high consumption of saturated fat and added sugar was associated with poorer hippocampal function and structure in humans.

STRENGTHS: The study conducted a systematic review and meta-analysis, which is a rigorous methodology for synthesising the findings of multiple studies. The authors used strict inclusion criteria and quality assessment tools to ensure that only high-quality studies were included in the review. The results were consistent across the studies reviewed and suggest a strong association between high intake of saturated fat and added sugar and reduced hippocampal function and structure.

LIMITATIONS: The review did not consider the effects of other dietary components such as protein, fibre, and micronutrients on hippocampal integrity and function. Also, the studies included in the review were cross-sectional or observational, meaning that causality could not be established.

SCIENTIFIC POWER: MODERATE - Overall, the study is well-designed and the findings are based on a rigorous methodology. However, the review is limited by the lack of randomised controlled trials, which would provide stronger evidence of causality.



Thomas, J., Thomas, C.J., Radcliffe, J. and Itsiopoulos, C., 2015. Omega-3 fatty acids in early prevention of inflammatory neurodegenerative disease: a focus on Alzheimer’s disease. BioMed Research International, 2015.


OVERVIEW: This article discusses the potential of omega-3 fatty acids to prevent neurodegenerative diseases, with a focus on Alzheimer's disease. The authors reviewed the literature on the effects of omega-3 fatty acids on inflammation, oxidative stress, and amyloid beta protein accumulation in the brain, which are all factors that contribute to the development of Alzheimer's disease.

STRENGTHS: The article provides a comprehensive overview of the potential benefits of omega-3 fatty acids in preventing Alzheimer's disease. The authors included studies from various research fields, including epidemiology, animal studies, and human clinical trials. The article also discusses the potential mechanisms by which omega-3 fatty acids may protect against Alzheimer's disease.

LIMITATIONS: The article is a narrative review, which means that the authors did not conduct a systematic search of the literature or use a pre-defined methodology to select the studies included. As a result, the review may be subject to bias or selective inclusion of studies.

SCIENTIFIC POWER: LOW to MODERATE - The article provides a good overview of the potential benefits of omega-3 fatty acids in preventing Alzheimer's disease. However, as a narrative review, the article is not as rigorous as a systematic review or meta-analysis. Therefore, the scientific power of this study is rated as low to moderate.



Tripathi, M., Vibha, D., Gupta, P., Bhatia, R., Srivastava, M.P., Vivekanandhan, S., Bhushan Singh, M., Prasad, K., Dergalust, S. and Mendez, M.F., 2012. Risk factors of dementia in North India: a case–control study. Aging & Mental Health, 16(2), pp.228-235.


OVERVIEW: The article investigates the risk factors for dementia in North India. The study design used is a case-control study. The researchers aimed to find the difference in the prevalence of risk factors in people with dementia compared to those without dementia.

STRENGTHS: The study design used in this research is a case-control study, which is considered a reliable way to identify risk factors. The study included a large number of participants, with 201 dementia cases and 201 controls. The researchers used a structured questionnaire to collect data, which is an established method for collecting data in this type of research.

LIMITATIONS: This study has some limitations. First, the researchers used a convenience sample, which may not represent the entire population of North India. Second, the study was conducted in a hospital setting, which may not be representative of the general population. Finally, the study relied on self-reported data, which may have some bias.

SCIENTIFIC POWER: MODERATE - Overall, the study design and sample size are strong, but the limitations and potential biases lower the scientific power.



Upthegrove, R. and Khandaker, G.M., 2020. Cytokines, oxidative stress and cellular markers of inflammation in schizophrenia. Neuroinflammation and Schizophrenia, pp.49-66.


OVERVIEW: The article explores the relationship between cytokines, oxidative stress, and cellular markers of inflammation in schizophrenia. The researchers aimed to understand the underlying mechanisms of inflammation and oxidative stress in the development of schizophrenia.

STRENGTHS: The article presents a comprehensive review of the current understanding of inflammation and oxidative stress in schizophrenia. The researchers have used various studies to support their findings, which helps to strengthen their argument. The article is written in an easy-to-understand language and provides an excellent introduction to the topic.

LIMITATIONS: As a review article, there is no new data presented, and the findings are not based on original research. The article does not provide a clear conclusion on the relationship between inflammation and schizophrenia, and the authors suggest that more research is needed.

SCIENTIFIC POWER: MODERATE - The article provides a good overview of the current understanding of inflammation and schizophrenia. However, as it is a review article, there is no new data presented, and the conclusions drawn are not based on original research, thus lowering its scientific power.



Walters, M., Hackett, K., Caesar, E., Isaacson, R. and Mosconi, L., 2017. Role of nutrition to promote healthy brain aging and reduce risk of Alzheimer’s disease. Current Nutrition Reports, 6, pp.63-71.


OVERVIEW: In this article, the authors discuss the role of nutrition in promoting healthy brain aging and reducing the risk of Alzheimer's disease. The article provides an overview of the nutrients and dietary patterns that have been shown to be beneficial for brain health and cognitive function, as well as the mechanisms by which these nutrients act on the brain.

STRENGTHS: The article provides a comprehensive overview of the literature on nutrition and brain health, covering a range of nutrients and dietary patterns. The authors also discuss the mechanisms by which these nutrients act on the brain, which helps to provide a deeper understanding of the topic. The article is well-referenced and includes both human and animal studies.

LIMITATIONS: The article does not provide a detailed discussion of the limitations of the studies discussed. The authors also do not provide a clear summary of the key takeaways from the literature, which may make it difficult for readers to distil the main points.

SCIENTIFIC POWER: MODERATE - The article is well-referenced and covers a wide range of nutrients and dietary patterns. However, the lack of detailed discussion of study limitations and clear summary of key takeaways may limit the scientific power of the article.



Winocur, G. and Greenwood, C.E., 2005. Studies of the effects of high fat diets on cognitive function in a rat model. Neurobiology of Aging, 26(1), pp.46-49.


OVERVIEW: This article discusses the effects of high-fat diets on cognitive function in a rat model. The authors explore the impact of both short-term and long-term exposure to high-fat diets on cognitive performance, as well as the potential mechanisms underlying these effects.

STRENGTHS: The article provides a detailed discussion of the literature on the effects of high-fat diets on cognitive function in a rat model. The authors also discuss potential mechanisms underlying these effects, which helps to provide a deeper understanding of the topic. The article is well-referenced and includes both behavioural and neurobiological studies.

LIMITATIONS: The article focuses solely on studies conducted in rats, which may limit the generalisability of the findings to humans. Additionally, the authors do not provide a clear summary of the key takeaways from the literature, which may make it difficult for readers to distil the main points.

SCIENTIFIC POWER: MODERATE to STRONG - The article is well-referenced and provides a comprehensive overview of the literature on the effects of high-fat diets on cognitive function in rats. However, the focus on animal studies and lack of clear summary of key takeaways may limit the scientific power of the article.



Witte, A.V., Kerti, L., Hermannstädter, H.M., Fiebach, J.B., Schreiber, S.J., Schuchardt, J.P., Hahn, A. and Flöel, A., 2014. Long-chain omega-3 fatty acids improve brain function and structure in older adults. Cerebral Cortex, 24(11), pp.3059-3068.


OVERVIEW: This study investigated the effects of taking omega-3 supplements on the brain function and structure of healthy older adults. The study recruited 65 participants who were randomly assigned to receive either omega-3 supplements or a placebo for six months. The researchers measured the participants' brain structure and function using magnetic resonance imaging (MRI) and cognitive tests before and after the intervention.

STRENGTHS: This study was a well-designed randomised controlled trial, which is considered the gold standard in research. The study used a large sample size and employed rigorous methods to ensure that the results were reliable. The use of MRI and cognitive tests to measure brain structure and function is a strength, as they are objective and reliable measures.

LIMITATIONS: One limitation of this study is that it was relatively short-term, lasting only six months. The study only looked at healthy older adults and did not investigate the effects of omega-3 supplementation in individuals with cognitive impairment or dementia. Additionally, the study did not measure other potential confounding factors that may have influenced the results, such as lifestyle factors.

SCIENTIFIC POWER: MODERATE to STRONG - The randomised controlled trial design and large sample size are strengths of this study. However, the short duration and the lack of investigation into individuals with cognitive impairment limit its scientific power.



Zhang, L., Liu, H., Kuang, L., Meng, H. and Zhou, X., 2019. Omega-3 fatty acids for the treatment of depressive disorders in children and adolescents: A meta-analysis of randomised placebo-controlled trials. Child and Adolescent Psychiatry and Mental Health, 13(1), pp.1-9.


OVERVIEW: This study aimed to investigate the effectiveness of omega-3 supplements in the treatment of depression in children and adolescents. The study conducted a meta-analysis of randomised controlled trials that investigated the effects of omega-3 supplements versus placebo in treating depressive disorders in children and adolescents.

STRENGTHS: This study was a meta-analysis of randomised controlled trials, which is a powerful research method. The study included a large number of trials and participants, making the results more robust. The study used strict inclusion criteria, which ensured that only high-quality studies were included in the analysis.

LIMITATIONS: One limitation of this study is that the included trials had varying dosages and duration of omega-3 supplementation, which may have affected the results. The study did not investigate the potential adverse effects of omega-3 supplementation, such as gastrointestinal symptoms or bleeding.

SCIENTIFIC POWER: MODERATE - The meta-analysis of randomised controlled trials is a strength of this study, as it provides a comprehensive overview of the available evidence. However, the varying dosages and durations of the included trials limit the study's scientific power.



Zhu, R.Z., Chen, M.Q., Zhang, Z.W., Wu, T.Y. and Zhao, W.H., 2021. Dietary fatty acids and risk for Alzheimer's disease, dementia, and mild cognitive impairment: a prospective cohort meta-analysis. Nutrition, 90, p.111355.


OVERVIEW: This article presents a meta-analysis of several prospective cohort studies investigating the relationship between dietary fatty acids and the risk of developing Alzheimer's disease, dementia, and mild cognitive impairment. The authors examined the intake of different types of fatty acids, including saturated, monounsaturated, polyunsaturated, and trans fats. They also explored the potential impact of dietary patterns, such as the Mediterranean diet, on cognitive function.

STRENGTHS: The study used a large sample size, including over 100,000 participants, and multiple cohort studies, providing strong evidence of the relationship between dietary fatty acids and cognitive function. The authors performed a thorough analysis of the different types of fatty acids, which is essential given the significant differences in their effects on cognitive function.

LIMITATIONS: The included studies used self-reported dietary intake data, which may not be entirely accurate. Moreover, most studies did not distinguish between dietary and supplement sources of fatty acids, and only a few studies accounted for confounding factors like physical activity or education level.

SCIENTIFIC POWER: MODERATE - Overall, this meta-analysis provides moderate scientific power to support the hypothesis that dietary fatty acids play a role in cognitive function. However, the limitations in the included studies should be considered when interpreting the findings.



Zou R, Labrecque J, Swanson SA, Steegers EA, White T, El Marroun H, Tiemeier H. Prenatal exposure to trans fatty acids in relation to brain development in fetal life and childhood: calendar time as an instrumental variable. Perinatal Determinants of Child Brain Development. 2021:163.


OVERVIEW: This article presents a study that investigated the impact of prenatal exposure to trans fatty acids on brain development during foetal life and childhood. The authors used a unique approach called "calendar time as an instrumental variable" to address potential confounding factors, such as unmeasured genetic or environmental factors that may influence the association between trans fatty acid exposure and brain development.

STRENGTHS: The study used a large sample size, including over 5,000 mother-child pairs, and accounted for several confounding factors, including maternal age, education, and smoking during pregnancy. The use of an instrumental variable approach is a strength, as it helps to minimise the impact of confounding variables and provides stronger evidence of causality.

LIMITATIONS: The study relied on a single measurement of maternal trans fatty acid intake during pregnancy, which may not reflect their overall exposure levels. The authors also did not account for potential confounding factors, such as postnatal exposure to trans fatty acids.

SCIENTIFIC POWER: MODERATE to STRONG - This study provides moderate to strong scientific power to support the hypothesis that prenatal exposure to trans fatty acids may have a negative impact on brain development during foetal life and childhood. However, the limitations of the study should be considered when interpreting the findings.



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