PureInsight | August 8, 2005
Did you know that the brain has the highest percentage of fat of any organ in the body? Like other organs, it renews itself constantly and needs certain fats to do so. For this reason, the brain's very structure depends on the quality of the fats we consume. Omega-3s make up a family of long chain n-3 fatty acids of which the brain is particularly fond.
Eicosapenteanoic acid (EPA) and docosahexaenoic acid (DHA) are the most researched omega-3 fatty acids.
Omega-3s and Brain Function
LA Horrocks and Y.K. Yeo point out in "Health Benefits of Docosahexaenoic acid (DHA)" in Pharmacological Research, September 1999; 40(3): 211-25: "Docosahexaenoic acid (DHA) is essential for the growth and functional development of the brain in infants. DHA is also required for maintenance of normal brain function in adults. The inclusion of plentiful DHA in the diet improves learning ability, whereas deficiencies of DHA are associated with deficits in learning. DHA is taken up by the brain in preference to other fatty acids…Decreases in DHA in the brain are associated with cognitive decline during aging and with onset of sporadic Alzheimer disease."
According to G. Young and J. Conquer in "Omega-3 Fatty Acids and Neuropsychiatric Disorders," published in Reproductive and Nutritional Development, Jan-Feb, 2005; 45(1): 1-28, "decreased blood levels of omega-3 fatty acids have been associated with several neuropsychiatric conditions, including Attention Deficit (Hyperactivity) Disorder, Alzheimer's Disease, Schizophrenia and Depression." The authors further state: "DHA is the predominant n-3 [omega-3] fatty acid found in the brain and that EPA plays an important role as an anti-inflammatory precursor. Both DHA and EPA can be linked with many aspects of neural function, including neurotransmission, membrane fluidity, ion channel and enzyme regulation and gene expression."
The best source for EPA and DHA are salmon. However, farm-bred salmon is not recommended since studies have shown that farm-bred salmon do not have the beneficial fatty acid composition of wild salmon. Sardines and mackerel are also good sources. Dining on six to eight ounces of salmon once a week has been recommended by studies.
Flaxseed oil and canola oil are recommended as omega-3 sources but they have relatively high contents of alpha linolenic acid (ALA), which can, in dietary doses, decrease eicosanoid synthesis.
Eicosanoids are hormones that can either promote or diminish inflammation. ALA, like aspirin, decreases the production of all eicosanoids. For a person suffering from an inflammatory condition, this might be thought to be helpful. However, the production of beneficial eicosanoids, such as gamma linolenic acid (GLA), is also diminished. By supplementing with EPA/DHA, the production of inflammatory eicosanoids is diminished, but the production of beneficial eicosanoids is maintained.
What About Supplements?
Most studies have demonstrated that supplementing with EPA and DHA is beneficial. This may be done in the form or liquid or capsule fish liver oil or cod-liver oil, provided that these supplements have been molecularly distilled to remove heavy metals and other toxins. Cod-liver oil is preferred as a source of vitamin D.
[Vegetarians should make sure to include a good source of ALA in your diet, the simplest source would be one teaspoon of flax seed oil a day, taken either on its own or mixed into dressings etc. Flax oil is also available in vegetable capsules. It must be very fresh and never heated. Alternately include 4 to 5 teaspoons of ground flax seeds, or rape seed oil in your diet – though do not heat any of the oils, and only add the flax seeds to any foods at a late stage since heating will destabilize the ALA. It is important that the flax seeds are ground or at least crushed, if left whole much of the fat will be unavailable.
One should replace fats high in omega 6 oils, such as sunflower oil or corn oil, with fats higher in monounsaturated fats, such as olive oil or rape seed oil which do not disrupt the formation of EPA and DHA. Other foods can add to your intake of ALA. Most of the little fat in leafy green vegetables is ALA – broccoli has 0.13g per 100g, cabbage 0.11g per 100g, so simply eating your greens is making a positive addition to your intake. Walnuts are and tofu are also good sources but are comparably high in LA. Pregnant or nursing mothers who are uncertain whether their diet is providing enough omega 3 fats may wish to consider supplementing their diet with a direct source of DHA since this appears to play an important part in the development of immature brains. DHA supplements derived from algae and encased in non-gelatin capsules are now available. Seaweed or spirulina, eaten in moderate quantities since the fatty acid content is low, is also a useful addition to the diet. Ed.]