Rosie Mestel - Los Angeles Times

Here, gleaned from omega-3 experts, are things to consider when thinking about increasing your fish-oil intake:

The American Heart Association recommends that healthy adults, especially those at higher risk for heart disease, sample a variety of fish at least twice weekly — preferably oily fish such as salmon, mackerel, sardines, herring and trout. These are the richest in the two fish omega-3s, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The heart association also recommends increasing intake of a different type of omega-3, known as alpha-linolenic acid, or ALA, which is abundant in walnuts, flax seeds, and canola and soybean oils.

People with preexisting heart disease should try to consume 1 gram of omega-3 oils each day, preferably from food. Individuals who need their blood triglycerides lowered may need an even bigger dose: 2 to 4 grams daily, which will presumably mean supplements (it's hard to eat that much fish).

Be mindful of, but not overly concerned about, potential contaminants in fish. We've all read about the problems of mercury in big fish, and in January a group of scientists reported that farmed salmon (about 90 percent of the fresh salmon found in supermarkets) contained 10 times more PCBs (polychlorinated biphenyls), dioxins and other potentially cancer-causing industrial chemicals than did wild salmon. The chemicals were acquired from the oil and the meal the fish were fed. The levels exceeded safety levels set by the federal Environmental Protection Agency for sport-caught fish.

"I advise consumers not to eat farmed salmon until the industry changes the way it feeds the salmon," says David Carpenter, director of the Institute for Health and the Environment at the University at Albany in New York.

But many nutrition scientists disagree that the PCB levels pose a risk. "I feel very strongly that people should eat salmon of all kinds — farmed, wild, whatever," says Mark Kantor, associate professor of nutrition and food science at the University of Maryland in College Park. Kantor and others say that the amounts of these chemicals in farmed salmon are still far below the safety levels set by the FDA.

Consider fish oil pills and capsules. Clinical trials have shown that capsules, not merely fish, protect the heart, and a 2003 Consumer Reports test showed that 16 major fish-oil supplements contained the advertised content of EPA and DHA, that the oils were in good shape and that contaminant levels were insignificant. Best bet: Check the label for the EPA/DHA levels, then pick your fish-oil supplement based on price.

If you can't eat fish oils, another alternative is a supplement of DHA extracted from algae — but experts point out that none of the clinical trials were conducted with DHA alone, so there's more uncertainty regarding the benefits. "The safest thing is to get both of them," says William Harris, professor of medicine at the University of Missouri in Kansas City.

For some people, fish-oil supplements may have side effects. Because of the oils' anti-clotting clout, people prone to excessive bleeding should take the supplements with caution. Other side effects from eating the oils are a fishy aftertaste or upset stomach. At higher doses diabetics and borderline diabetics may experience a worsening of blood-sugar control, and people with high blood triglyceride levels may find their LDL (or "bad") cholesterol levels go up.

Plant sources are a possibility — but you won't be getting the same substance as you would if you ate fish. Alpha-linolenic acid, the plant omega-3 abundant in walnuts, flax seeds and canola oil, is an essential oil: The Institute of Medicine recommends we eat at least a gram of it a day through food. In the body, ALA very slowly converts to DHA and EPA. But controlled clinical trials haven't shown that ALA protects the heart, although population studies suggest that it does.

Consider omega-3-rich eggs (but because of their cholesterol, don't overdo it). These are derived from feeding either fish meal, plant oils or DHA obtained from algae to chickens. Since the plant-based sources aren't rigorously shown to be heart-protective, nutrition experts recommend choosing the algae or fish oil eggs over the ALA ones — although an ALA egg may be better than a standard one.

Rosie Mestel, Los Angeles Times

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