Journal: American Journal of Clinical Nutrition, 2007 May;85(5);1222-8
Authors and affiliation: Metcalf RG, James MJ, Gibson RA, Edwards JR, Stubberfield J, Stuklis R, Roberts-Thomson K, Young GD, Cleland LG. Rheumatology Unit and the School of Medicine, University of Adelaide, Adelaide, Australia.
Background: Increased fish or fish-oil consumption is associated with reduced risk of cardiac mortality, especially sudden death. This benefit putatively arises from the incorporation of the long-chain n-3 [omega-3] fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into cardiomyocyte phospholipids [fatty acids found in the heart muscle cells].
Objective: The study examined the kinetics of incorporation of n-3 fatty acids into human myocardial membrane phospholipids during supplementation with fish oil and alpha-linolenic acid-rich flaxseed oil.
[Note: Omega-3 and omega-6 fatty acids are both essential to cellular function and must be obtained through the diet. Omega-3 EPA and DHA is found most commonly in fish and fish oil. Omega-3 ALA is found in vegetable oils such as olive and flax seed oil. Omega-6 (arachidonic acid) is synthesized from the linoleic acid in animal foods such as meat, eggs, dairy. Researchers believe the optimum balance of omega-3 to omega-6 essential fatty acids in the cells is one-to-one, whereas in most developed countries the scale is tipped significantly toward omega-6 – a diet-based situation they believe may promote chronic inflammation and a number of physical disorders.]
Design: Patients with low self-reported fish intake (<1 fish meal/wk and no oil supplements) accepted for elective cardiac surgery involving cardiopulmonary bypass were randomly allocated to 1 of 6 groups:
Fish oil (6 g EPA+DHA/day) for either 7, 14, or 21 days before surgery;
Or olive oil (both 10 mL/d for 21 days before surgery).
Right atrial appendage tissue removed during surgery and blood collected at enrollment and before surgery were analyzed for phospholipid fatty acids.
Results: Surgery rescheduling resulted in a range of treatment times from 7 to 118 days.
In the fish-oil-treated subjects, accumulation of EPA and DHA in the right atrium was curvilinear with time and reached a maximum at approximately 30 days of treatment and displaced mainly arachidonic acid [omega-6];
Flaxseed oil supplementation yielded a small increase in atrial EPA but not DHA;
Whereas olive oil did not significantly change atrial n-3 fatty acids.
Conclusion: The results of the present study show that dietary n-3 fatty acids are rapidly incorporated into human myocardial phospholipids at the expense of arachidonic acid during high-dose fish-oil supplementation.