Nervous System

Low omega-3 levels impair cognitive abilities

Brain: low omega-3 indices impair cognitive function

Lower-than-average blood levels of Omega-3s impair cognitive abilities, but diet and supplements could help counteract the problem . Low levels of Omega-3 in the body impair cognitive abilities, but increasing consumption of foods or supplements rich in these molecules could help bring them back to normal. Hypothesizing this are the authors of a study published in Nutritional Neuroscience, who showed that having lower than the population average amount of these fatty acids in the blood reduces cognitive flexibility, that is, the ability, when necessary, to shift one's attention from one subject to another. At the same time, reduced levels of Omega-3 are associated with decreased executive functions, that is, the ability to plan, control and coordinate cognitive activities.

The importance of Omega-3s for the body

Omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are important for both development and the functioning of the nervous system. Not only that, the benefits carried out by these molecules towards other organs and tissues, especially those of the cardiovascular system, have long been known. The human body is not, however, able to synthesize them fully independently. In particular, cells know how to obtain DHA from EPA, but their ability to synthesize the latter from its precursor (alpha-linolenic acid or ALA) is reduced.ALA, in turn, cannot be produced by the body, so it is very important to ensure a proper supply of Omega-3 through the diet.

The effects of omega-3 deficiency on the nervous system

Researchers have previously shown that low levels of DHA are associated with an increased risk of suicide among deployed military personnel. The authors of the study published in Nutritional Neuroscience also involved a group of military personnel in their research and found that the amount of EPA and DHA present in their red blood cells were lower than those detectable in the U.S. population of the same age. Specifically, the percentage of these Omega-3s in the red blood cells of the servicemen was 3.5 percent, compared with the 4.5 percent typical of the population of the same age. The researchers were not very surprised by this difference, which can be justified by the diet followed by deployed servicemen, which is generally low in Omega-3s. More surprising, however, was finding that low levels of these nutrients were associated with lower cognitive flexibility and impaired executive functions. Analysis of data collected during psychosocial and neurocognitive tests, moreover, revealed that the link between low Omega-3 levels and reduced cognitive abilities was particularly close in those who reported suffering from sleep disorders. Not only that, servicemen who could not rest well but who had higher Omega-3 levels than the average study participant appeared to have greater ability to recover from fatigue and better cognitive flexibility and executive functions.

Nourishing the brain with omega-3s

The hypothesis developed by the authors is that the decrease in cognitive ability could be counteracted by increasing the levels of EPA and DHA in the body either by eating more Omega-3 rich foods or by taking fish oil supplements. The study aimed at testing this hypothesis has already been conducted. Publication of its results is expected by the end of this year.


1. Johnston DT, Deuster PA, Harris WS, Macrae H, Dretsch MN, "Red blood cell omega-3 fatty acid levels and neurocognitive performance in deployed U.S. Servicemembers," Nutr Neurosci. 2012 Jun 28 2. Lewis MD, Hibbeln JR, Johnson JE, Lin YH, Hyun DY, Loewke JD, "Suicide deaths of active-duty US military and omega-3 fatty-acid status: a case-control comparison," J Clin Psychiatry. 2011 Dec;72(12):1585-90. Epub 2011 Aug 23