The essential fatty acids α-linolenic acid (ALA, C,18:3 (n-3)) and linoleic acid (LA, C18:2 (n-6)) are required for the formation of the eicosanoid signal molecules which regulate cellular function. Because of the wide ranging modulation of cellular activity by eicosanoids, deficiency of the essential fatty acids can result in a number of heath complaints relating to oxidative damage, inflammation, coagulation and fatigue. Cardiovascular disease and chronic inflammation have been research extensively with regard imbalances in dietary essential fatty acid intakes, and results from clinical trials and epidemiology support a role for essential fatty acid deficiency in these conditions. Interestingly, depression is often associated with cardiovascular disease and inflammation, suggesting that imbalances in dietary ALA and LA intake, or their metabolites eicosapentanoic acid (EPA, C20:5 (n-3)) and docosahexanoic acid (DHA, C22:6 (n-3)) may be intimately involved in the formation of this disorder.
The fact that n-3 long chain fatty acid supplementation is beneficial to depression suggests that intakes of essential fatty acids may be able to influence mood and well being. For example, in an 8 week randomised, double blind, placebo-controlled study1, 46 depressed women ages 66 to 95 years had amelioration of their depressive symptoms with supplementation of 2.5g/d of n-3 fatty acids. The fatty acids were supplied in the form of the fish oils EPA and DHA at 1.67g/d and 0.83g/d, respectively. The depressive symptoms were assessed using the Geriatric Depression Scale and quality of life was assessed by using the Short-Form 36 Item Health Survey. The response rate for relief of depression was 45% in the treatment group but only 8.3% in the control group. These results therefore support a role for the long-chain polyunsaturated marine oils in relief from depression.
The researchers also assessed the plasma phospholipids of the subjects using gas chromatography. The mean arachidonic acid (AA, C20:4 (n-3)) to EPA ration was significantly decreased in the treatment group compared to the control group by week 8. This suggests that supplementation was effective at increasing plasma phospholipid levels of EPA and was also beneficial in terms of reducing cell membrane levels of arachidonic acid, a potential precursor of pro-inflammatory and pro-thrombotic mediators. The authors of the study masked the taste of the supplements and placebo with the same strong lemon flavour to maintain the double blind nature of the trial, suggesting that the significance of the result was not altered by the placebo effect. Docosahexanoic acid is found in high concentrations in the brain tissue and is required for correct brain function, so it is not surprising that supplementation in beneficial to mental health.
RdB
