Omega-3 fatty acids and brain function

Peer-reviewed | Manuscript received: February 12, 2015 | Revision accepted: June 11, 2015

Introduction

Although interest in the omega-3- fatty acids (n3-FAs) has mostly been concentrated on their possible cardiovascular effects (see article on page M596 in this issue), increasing attention is now being paid to their putative significance for cognitive function and in neurodegenerative diseases. As the prevalence of these diseases has been rising for years, we can expect a lively discussion of the role of nutrition and, particularly, of the n3-FAs in this context. The present review article presents the current state of research and explains the developments in this area.

Physiological significance

Neuronal development and brain structure

n3-FAs are essential elements in the assembly, maturation and physiological function of neuronal structures [1] (• Figure 1). Docosahexaenoic acid (DHA) accumulates in the brain of the fetus during neuronal development already in the third trimester of pregnancy; this process continues during the first two years of life [2, 3]. Optimal neuronal development is then highly dependent on the supply of long chain polyunsaturated fatty acids (LCPUFAs) [1].

Summary

It is generally accepted that omega-3-fatty acids (n3-FAs) are important for the development, physiology and (presumably) also the perfusion of the human brain. On the other hand, the available studies do not demonstrate that n3-FAs can protect against age-related loss of cognitive performance - even though this is supported by positive epidemiological correlations. It has not been shown that n3-FAs lead to improved cognitive performance or reduce the incidence of dementia. This may be due to the host of methodological problems, rather than any inherent lack of activity. Epidemiological studies on the correlation between n3-FA intake with food and the incidence of Alzheimer‘s disease do not provide any valid evidence. Supplementation does not influence the incidence of Alzheimer‘ s disease in healthy subjects and has no clinically relevant effects on patients with the disease. The same applies to Parkinson‘s disease. Depression is the only neuropsychiatric disease that can be demonstrably influenced by supplementation with eicosapentaenoic acid (EPA).

Future studies on the role of n3-FAs in age-related loss of cognitive performance should lay greater weight on the multifactorial pathogenesis of these conditions. They must employ realistic observation periods, and with pharmacologically based dose finding. In the near future, we can expect numerous studies on the role of n3-FAs in neuropsychiatric diseases, as indications such as depression, attention deficit hyperactivity disorder (ADHD) and learning difficulties in children open new vistas in nutritional science and are potentially of considerable economic importance.

Keywords: omega-3 fatty acids, docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), fish oil, dementia, cognitive function, brain function 

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