Dietary Fats and Intellect: Western-style Diets Impair Cognitive Development

The composition of the fats in ones diet can have profound effects on health, both in the short-term and the long-term. Most people have become familiar with the scientific evidence that correlates disease, particularly cardiovascular disease and cancer, with the consumption of the particular types of fats called trans-fats. Indeed, the evidence of disease causality is so strong that most countries, including the US, ban the inclusion of trans fats in manufactured foods. Most people have also become familiar with the health benefits of consuming foods rich in the type of fats called omega-3 fatty acids (in particular the omega-3 polyunsaturated fatty acids, PUFA)---think fish and fish oil supplements. Indeed I have blogged on numerous occasions about healthy fats in the diet and about the health benefits of omega-3 fatty acids and how a healthy dietary life-style includes foods enriched in these particular fats:

Beneficial Dietary Oils: Fats are not Always Bad for You

Medium-Chain Triglycerides (MCT): What are they and Should You Care?

Fish Oil Versus Krill Oil: Are There Differences and Any Real Benefits?

Palmitoleic Acid: An Anti-Aging Fatty Acid?

Docasoapentaenoic Acid, DPA: The Overlooked Omega-3 PUFA?

Dietary Fats (Omega, MUFA, and PUFA): An Overview of What You Need to Know

Several clinical and laboratory studies have been carried out in recent years and all have demonstrated a significant correlation between dietary ratios of two distinct classes of polyunsaturated omega fatty acids and parameters of health. As a brief general overview there are two main types of omega PUFAs, the omega-6 and the omega-3 forms. The primary omega-6 PUFA is called arachidonic acid. There are several important omega-3 PUFAs as can be seen in several of my previous posts outlined above, but the two that most people have become familiar with are called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). When utilized by the body arachidonic acid serves as a precursor for biologically active lipid metabolites that are, generally, pro-inflammatory. The biologically active metabolites of EPA and DHA are, generally anti-inflammatory. Now granted this a rather simplified assessment of the function of these various types of omega fatty acids, but it is useful to emphasize the simplified consequences of differing ratios of omega-6 and omega-3 PUFA intake in the diet. In general, the typical Westernized diet, that is rich in animal fats and low in plant-derived fats, results in a ratio of omega-6 PUFA to omega-3 PUFA on the order of 20-50 to 1. Numerous clinical studies have shown that this ratio is directly correlated to the development of certain cancers and to a significantly increased likelihood for the development of cardiovascular disease. The optimal ration of omega-6 to omega-3 PUFA is suggested by scientific evidence to be 2 to 1. This ratio allows for a fine balance between activation of inflammation when appropriate, but also allows for a timely resolution and inhibition of the inflammation when the initial activating signal has been dealt with.

Many studies have also demonstrated a correlation between omega-6 PUFA and omega-3 PUFA levels in the diet and higher order mental functioning. One major benefit of the omega-3 PUFA, DHA, is that is has been shown to be a critical determinant on fetal and neonatal brain development. Indeed, the evidence is so striking that essentially all infant formulas now include DHA and promote the benefits of this added supplement.

Cognitive functioning, such as memory, has been demonstrated to be highly sensitive to dietary omega-6 to omega-3 ratios. Within the central nervous system both omega-6 and omega-3 PUFAs are important in the overall concentration of various neurotransmitters in nerve cells and they contribute to neuronal growth and development. There is a competition that exist between to fuinctions of omega-6-derived bioactive lipids and omega-3-derived bioactive lipids such that an imbalance in the ratios of these PUFAs results in decreases of the products of one or the other. Research has shown that a balanced dietary ratio of omega-6 to omega-3 PUFA results in the optimal distribution of these fatty acids within tissues of the brain. Dietary deficiency of omega-3 PUFAs has been linked to numerous cognitive deficits in laboratory animals. Quite strikingly, a diet that is weighted in omega-6 PUFA can lead to deficiencies of omega-3 PUFA distribution into the brain regardless of the amount of omega-3 PUFA in the diet.

A recent study published in the American Journal of Clinical Nutrition demonstrates that an optimal ration of omega-6 to omega-3 PUFA in the diet of children is crucial for overall cognitive development:

Executive functions and the ω-6 to ω-3 fatty acid ratio: a cross-sectional study

Although the results of this study are complex given that age-related differences in cognitive benefits were found for dietary omega-6 and omega-3 ratios and differences were observed when functions associated with different regions of the brain were analyzed. However, a novel, critical, and significant finding of this study was that brain functioning requires an optimal balance of both omega-6 PUFA intake and omega-3 PUFA intake. Some of the findings included a demonstration that a diet consisting of a balanced omega PUFA ratio was a significant predictor for planning performance in children aged 7-9 years, whereas increased omega-3 intake correlated with enhance performance in children aged 10-12. The later is predicted to be due to the changes in metabolic activity in the brains of pre-pubertal children. These results emphasize that there are likely to be other age-related differences in cognitive functioning and omega PUFA ratios.

An important TAKE HOME from this study, especially when correlated to many other studies on the significance of omega-6 to omega-3 ratios in the diet, is that when one consumes a typical Westernized diet they are not only promoting the potential for many forms of cancer and enhancing their risk for heart disease, but they are also promoting a decline in their cognitive functions which are likely to worsen as one ages.

Eat wisely people, stay healthy and SMARTER!!!


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