Q. We know the benefits of fish oil with its omega-3 fatty acids. Is eel (unagi) high in omega-3?

A. Yes, unagi is high in omega-3, but the headline, "Doubts raised over health benefits of omega-3 fats" appeared in various papers last year because of a systematic review published March 26 in the British Medical Journal which pooled the results of 89 recent studies of omega-3 fatty acids and found that they did not lower the chance of having a heart attack, of getting cancer, of suffering a stroke or of dying. And some studies show actual harm.

In 2003, Dr. Michael Burr and others from England studied 3,114 men with angina, or chest pain due to blockage of their heart vessels. After several years, those who took fish oil capsules had 45 percent more deaths from heart disease than those who did not.

The high omega-3 fatty acid content of oily fish in the diet of Eskimos and other fish eaters supposedly leads to their lower heart disease rate seen in observational studies. However, it may be that something else in their heredity, lifestyle or diet is responsible.

To sort this all out, we need to find more accurate randomized studies rather than rely on weaker observational ones. The highly regarded Cochrane Collaboration found 48 randomized studies of omega-3s involving 36,913 people. About half were randomly selected to ingest extra omega-3 fatty acids in the form of oily fish (mackerel, salmon, trout, tuna, etc.), fish oil capsules, or plant oils such as flax seed oil. They found that ingesting oily fish, fish oil capsules or plant oils, either alone or in combination, did not reduce heart disease, cancers or deaths. This held true for both healthy people and those at high risk for heart disease.

The other bible for reliable health information besides Cochrane is the book "Clinical Evidence," which is updated twice a year. Like Cochrane, it only analyzes more accurate randomized controlled trials, a central concept of "evidence-based medicine." So which treatments really work in folks who already had heart disease? Clinical evidence found that various drugs and cardiac rehabilitation (including exercise) were clearly beneficial. The Mediterranean diet and stopping smoking were likely to be beneficial. But it found that eating more fiber and — like Cochrane — that ingesting more fish oil from capsules or oily fish were of unknown effectiveness. Unlikely to be beneficial were antioxidant vitamin combinations, multivitamins and vitamin C. And likely to be ineffective or even harmful were beta-carotene and vitamin E.

So I would not buy beta-carotene, vitamin E, antioxidant, or fish oil capsules. But I would eat Mediterranean!

Dr. Landis Lum is a family-practice physician for Kaiser Permanente and an associate clinical professor at the University of Hawai'i John A. Burns School of Medicine. Send questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Hono-lulu, HI 96802; islandlife@honoluluadvertiser.com; or fax 535-8170. This column is not intended to provide medical advice.