Supplementation with fish oils has been shown to increase erythrocyte levels of eicosapentanoic acid (EPA, 20:5 (n-3)) and docosahexanoic acid (DHA, 22:6 (n-3)). Studies have also shown that supplementation of fish oils reduces cardiac deaths by 42 to 67 % and cardiac death with or without nonfatal myocardial infarction by 32 to 73 %. Another study recorded a 45 % reduction in sudden cardiac death with fish oil supplementation. In case-control studies those with the highest erythrocyte levels of n-3 polyunsaturated fatty acids had a 90 % reduction in the risk of primary cardiac arrest. Both EPA and DHA accumulate in cell membranes where they displace arachidonic acid (AA, 20:4 (n-6)), which may be he mechanism of their benefit. Arachidonic acid is the precursor to inflammatory series-2 prostanoids, whereas EPA and DHA are precursors to the non-inflammatory series-3 prostanoids (here).
Research published in the American Journal of Clinical Nutrition in 20071 investigated the effect of fish oil supplementation of accumulation of n-3 fatty acids in cardiac muscle phospholipids. Individuals who had a low consumption of fish (< 1 time per week) and who took no fish oil supplementation but were due to undergo elective cardiac surgery, were fed either fish oil containing 6 grams of EPA and DHA for between 7 to 63 days before surgery; 10 mL flax seed oil for between 18 to 118 days before surgery; 10 mL olive oil for between 15 to 79 days before surgery; or no oil supplements. Variation in treatment duration was because of rescheduling of surgery. Cardiac tissue (right atrial) removed during surgery, and blood collected both before and during surgery, was analysed for fatty acids.
The results of this study showed that EPA and DHA levels increased as duration of supplementation increased up to ~ a 30 day maximum. As n-3 polyunsaturated fatty acid content (PUFA) of cardiac tissue increased, n-6 PUFA (Mainly AA) content was lowered in a reciprocal manner. There was no effects of fish oil supplementation on saturated or monounsaturated fatty acid content of cardiac tissue. Flax oil supplementation increased alpha linolenic acid (ALA, 18:3 (n-3)) content of cardiac tissue, and also raised EPA levels by ~50 % but this difference was not significant. This supports previous studies that show that flax oil is able to raise ALA phospholipids levels but is not as effective as fish oil at raising levels of EPA or DHA. Olive oil and the no supplements groups did not have detectable changes in phospholipids fatty acids.
RdB
