Eat Fish for a Healthy Heart

Eating fish regularly is associated with lower risk of fatal heart disease in men and women, according to studies recently published in the Journal of the American Medical Association and the New England Journal of Medicine.^{1 2}

Researchers in one study compared the diets of women who suffered heart attacks with the diets of those who did not and found that there was a statistically significant benefit from frequent consumption of fish. Women consuming fish five or more times per week were found to have 45% fewer fatal heart attacks compared with women who ate fish less than once per month.

Another study compared the blood concentrations of the fats found in fish oil (known collectively as omega-3 fatty acids) between healthy participants and those that suffered sudden cardiac death. Researchers found that participants with the lowest concentrations had over five times the risk of suddenly dying of heart disease, compared with the men with the highest concentrations.

The first study examined the dietary habits (most notably, the amount of fish in the diet) of 84,000 American nurses between the ages of 34 and 59 years. Over the 16-year follow-up period, there were 484 fatal heart attacks and 1,029 nonfatal heart attacks in the study cohort.

The second study examined the blood levels of fatty acids in 22,000 male American doctors. During the 17-year follow-up period, the researchers kept track of sudden death from heart disease in participants with no diagnosed symptoms prior to a fatal event. Of the initial group, 84 subjects met the criteria for sudden cardiac death.

The best sources of omega-3 fatty acids are the species of fish with darker meat, including salmon, mackerel, and swordfish. Canned tuna, shellfish, and white meat fish contain about 1/3 to 1/4 of the omega-3 fatty acids per serving found in salmon. Fish oils are also available as a nutritional supplement.

There are at least two known mechanisms by which fish oils may be beneficial to cardiac health. First, omega-3 fatty acids have been shown to slow the process of hardening of the arteries.³ Also, these fats are thought to prevent disturbances of the heart rhythm.⁴ These new studies are part of a growing body of evidence that fish oils are protective against death from heart disease.^{5 6 7 8}

The optimal intake of omega-3 fatty acids from fish oil is still under debate. Some clinical trials have used either 3 grams of purified omega-3 fatty acids or 2 tsp of whole fish oil (usually as cod liver oil). In light of recent research, eating fish several times per week could be beneficial as well.

References:

1. Hu FB, Bronner L, Willett WC, et al. Fish and omega-3 fatty acid intake and risk of coronary heart disease in women. JAMA 2002;287:1815–21.
2. Albert CM, Campos H, Stampfer MJ, et al. Blood levels of long-chain n-3 fatty acids and the risk of sudden death. N Engl J Med 2002;346:1113–8.
3. von Schacky C, Angerer P, Kothny W, et al. The effect of dietary omega-3 fatty acids on coronary atherosclerosis. A randomized, double-blind, placebo-controlled trial. Ann Intern Med 1999;130:554–62.
4. Nair SS, Leitch JW, Falconer J, Garg ML. Prevention of cardiac arrhythmia by dietary (n-3) polyunsaturated fatty acids and their mechanism of action. J Nutr 1997;127:383–93.
5. Daviglus ML, Stamler J, Orencia AJ, et al. Fish consumption and the 30-year risk of fatal myocardial infarction. N Engl J Med 1997;336:1046–53.
6. Burr ML, Fehily AM, Gilbert JF, et al. Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction: diet and reinfarction trial. Lancet 1989;2:757–61.
7. Singh RB, Niaz MA, Sharma JP, et al. Randomized, double-blind, placebo-controlled trial of fish oil and mustard oil in patients with suspected acute myocardial infarction: the Indian experiment of infarct survival--4. Cardiovasc Drugs 1997;11:485–91.
8. [No authors listed]. Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto miocardico. Lancet 1999;354:447–55.

Matt Brignall, ND, is in practice at the Seattle Cancer Treatment and Wellness Center and at the Evergreen Integrative Medicine Clinic in Kirkland, WA. He specializes in integrative treatment of cancer. He is a contributor to Healthnotes and Healthnotes Newswire.

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