General Health: Is fish oil fishy?

Is fish oil pass?

Health fads come and go, even in alternative health. A substance that received a good deal of acclaim a few years ago is fish oil. Recently, however, we have not heard so much about this product from the deep, as herbs seem to be the growing topic in health magazines and the popular press. Has fish oil lost its health luster?

Fish oil first burst onto the cardiovascular scene in the 1970s, when epidemiological studies looking at the consumption of fish in relation to cardiovascular disease revealed that Eskimo populations that consume large quantities of fish show relatively low evidence of cardiovascular disease. This led to numerous studies exploring the potential link between fish and cardiovascular health.

Further research on fish and fish oil resulted in a tug of war. One study confirms their health benefits; another "proves" that benefits are exaggerated. A newer study reconfirms their benefits yet again, only to be "second-guessed" by yet another study.

What was this tug of war and who won? Initially, it was over fish and fish oil’s effect on lipid (fats, such as cholesterol and triglycerides) levels. Consuming fish oil was said to lower, then raise, then lower, then raise cholesterol levels. One point that was agreed upon was that fish oil lowers triglyceride rates.

And as for cholesterol levels? The debate over whether fish oil reduces or increases LDL cholesterol levels can perhaps best be summed up by W.S. Harris, as cited by Neil Stone, M.D., in a 1997 issue (65:4) of the American Journal of Clinical Nutrition.

Stone notes that in the majority of studies reporting reductions in LDL cholesterol levels, the subjects’ consumption of saturated fat had also been lowered when they switched from a control diet to a diet that included fish oil. However, when the consumption of saturated fat intake remained constant, the inclusion of fish oil appeared to result in an increase or in no change in LDL cholesterol levels.

This fact-that those who consume a more "standard" Western diet and fish oil may experience an increase in LDL cholesterol levels-has been noted by researchers, and studies have been performed in which cholesterol-lowering foods were taken along with fish oil. Adler and Holub, writing in the American Journal of Clinical Nutrition (1997;65:2), say, "In conclusion, garlic supplementation significantly decreased both total cholesterol and LDL cholesterol, whereas fish oil supplementation significantly decreased triglyceride concentrations and increased LDL cholesterol concentrations in moderately hypercholesterolemic men. The combination of garlic and fish oil prevented a moderate fish oil-induced rise in LDL cholesterol."

There has also been a "back and forth" on how fish and fish oil affect cardiovascular health. Results are beginning to indicate that consuming omega-3 fatty acids, as found in fish and fish oil, "may reduce vulnerability to a ventricular fibrillation and, thereby, reduce the risk of coronary heart disease mortality." (Journal of the American Medical Association. 1995. 274:17)

The most recent word on the role of fish oil in cardiovascular health is overwhelmingly positive. Susan and William Connor, in a review of fish oil and its effect on coronary artery disease (American Journal of Clinical Nutrition. 1997. 66:4[S]), state

"The omega-3 fatty acids of fish and fish oil have great potential for the prevention and treatment of patients with coronary heart disease. Unlike many of the pharmaceutical agents used in patients with coronary artery disease that have just a single mechanism of action, the eicosa-pentaenoic and docosahexaenoic acids of fish oil have multifaceted actions. One of their most important effects is the prevention of arrhythmias. ... Especially important is the ability of these omega-3 fatty acids to inhibit ventricular fibrillation and consequent cardiac arrest. ... These composite effects suggest a prominent therapeutic role for fish oil in the prevention and treatment of coronary artery
disease. …

"In conclusion, omega-3 fatty acids from fish and fish oil greatly inhibit the atherosclerotic process and coronary thrombosis by many actions and should be considered as an important therapeutic modality in patients with coronary artery disease and to prevent coronary artery disease in highly susceptible people."