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Fish and Fish Oil's Benefits Far Outweigh Risks

Omega-3 protection trumps mercury toxin risk, studies find

TUESDAY, Oct. 17, 2006 (HealthDay News) -- Americans looking for safe, healthy eating should focus first on fish, according to two government-funded reviews that weighed the pros and cons of eating the finned food.

The verdict: "Fish is likely the single most important food to eat for health, based on the evidence," said the co-author of one of the studies, Dr. Dariush Mozaffarian, an instructor in the department of epidemiology at the Harvard School of Public Health.

That study was funded by the U.S. National Heart, Lung, and Blood Institute, and is published in the Oct. 18 issue of the Journal of the American Medical Association.

Mozaffarian said that while a few species do contain worrisome levels of mercury and other contaminants, "when both risks and benefits are considered for the general population, the benefits of fish intake far outweigh the possible risks."

The second major analysis, funded by the Institute of Medicine (IOM), found similar results based on a review of the literature. The IOM panelists agreed that while certain long-lived species may pose a mercury risk to women and young children, fish on the whole is good for Americans. Those results, contained in a report titled Seafood Choices: Balancing Benefits and Risks, were announced at a Washington, D.C., news conference on Tuesday.

"Both studies come out with the same conclusion -- seafood is safe and nutritious and Americans should incorporate a variety of seafood in their diets to reduce risk of death from heart disease. In fact, there's a bigger health risk associated with not eating seafood among adults due to coronary heart disease, the primary cause of death among Americans," William T. Hogarth, director of National Marine Fisheries Service, said during the news conference.

One nutrition expert agreed with the findings, especially when it comes to the omega-3 fatty acids found in oily fish such as mackerel, salmon and sardines.

"Omega-3s are, right now, the superstars of the nutrition world," said Katherine Tallmadge, a Washington, D.C., nutritionist who's a spokeswoman for the American Dietetic Association. "There's no question about it -- this is a really critical nutrient that we need, and hardly any Americans are getting enough."

By now, most Americans have heard of the health benefits of omega-3 fatty acids, which are found in greatest abundance in oily, cold-water fish such as herring, mackerel, sardines, salmon and anchovies. There are two main omega-3s -- eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Among other benefits, these compounds are thought to aid in fetal, infant and child neurological development and also protect adults against cholesterol and heart disease.

But oily fish have a darker side. Industrial toxins can make their way into the water supply and end up in concentrated form in the flesh of these fish. Methylmercury, especially, has been linked to developmental problems in newborns and heart, nervous system and kidney damage in adults. For this reason, the U.S. Environmental Protection Agency and the U.S. Food and Drug Administration have each issued warnings about the consumption of a few -- but certainly not all -- fish species by women of childbearing age.

So, is regular fish consumption still good for most people? To find out, Mozaffarian and co-researcher Eric Rimm pored over dozens of studies on the subject conducted up to the spring of this year.

They found that the benefits of fish for heart health far outweighed any risks for the vast majority of consumers. For example, even modest consumption of fish -- one to two servings a week -- cut the overall death risk by 17 percent and deaths from coronary causes by 36 percent, especially if those fish were of the more oily varieties.

Even 250 grams a day of omega-3 fatty acids, considered a relatively low level, were sufficient to start protecting the heart, the researchers said. Ideally, this level of intake could come from just one 6-ounce serving a week of wild salmon or other oily fish. Alternatively, it could come in the form of a fish-oil supplement, the researchers said.

The IOM report agreed with those findings. The agency said it is not yet clear whether the cardiac benefits of fish stem from omega-3 fatty acids, or whether people are simply "substituting the lean protein of seafood for fatty cuts of meat" in their diet.

Caveats remain, however. The Harvard team said that, due to high mercury content, pregnant women or women who believe they could become pregnant are still advised to avoid four fish species: King mackerel (not Atlantic mackerel); shark; swordfish; and golden bass (also known as tilefish). The IOM said another species, white albacore tuna, should only be consumed in amounts under 6 ounces per week.

Because omega-3s are so beneficial for the developing fetus, pregnant women are strongly encouraged to eat all other fish species, Mozaffarian said.

In its recommendations, the IOM panel also suggested that pregnant women and children under 12 years of age consume up to 12 ounces per week of all seafood species except shark, swordfish, tilefish or king mackerel. They especially recommended those species rich in omega-3 fatty acids.

The IOM report did have its critics, however. One consumer advocacy group questioned the IOM's decision to lump small children in with pregnant women as it drew up its recommendations. "They seem to be unaware that children are smaller than adults," Jean Halloran, director of food safety at Consumers Union, told the Associated Press. "That advice, which they featured prominently, could result in young children getting excessive doses of mercury."

Mozaffarian also noted that not all fish dishes are created equal.

"The average fried fish in the U.S. -- a commercially prepared, fried-fish meal -- does not have significant cardiovascular benefit, and may even harm you," he said. The unhealthy oils used in deep-frying appear to cancel out any benefits from the fish, which, in any case, are usually non-fatty species such as cod.

Tallmadge agreed, adding that "canned salmon is probably a nice economical choice," however. "It's usually [caught] wild. The wild salmon is leaner and has proportionally higher levels of omega-3s than farm-bred varieties," she said.

The American Heart Association currently recommends that heart patients take in 1,000 milligrams of omega-3s daily, and healthy individuals consume between 500 and 1,000 milligrams a day. For comparison purposes, Tallmadge noted that a typical 3.5 ounce serving of sardines in sardine oil contains about 3,300 milligrams of omega-3 fatty acids; a similar serving of Atlantic mackerel has 2,500 milligrams; Atlantic herring has 1,600 milligrams; Atlantic salmon, 1,200 milligrams; brook trout, 500 milligrams; and shrimp or flounder, 300 milligrams.

And what about fish-oil supplements? According to Tallmadge, the labeling on many popular supplements can be misleading.

"On the front of the bottle, they'll announce, '1,200 milligrams' of fish oil," she said, "but then when you read the fine print on the back, what's important to look for is the amount of EPA and DHA." Often, that amounts to just 20 or so percent of the pills' volume.

Tallmadge tells her clients to go for an FDA-regulated, prescription omega-3 pill, Omacor (900 milligrams per pill). Then, at least, they know what they're paying for, she said.

More information

There's more on omega-3 fatty acids at the American Heart Association.

SOURCES: Oct. 17, 2006, press conference with Dariush Mozaffarian, M.D., instructor, department of epidemiology, Harvard School of Public Health, Boston, and William T. Hogarth, director, National Marine Fisheries Service; Katharine Tallmadge, R.D., M.A., dietitian, Washington, D.C., and spokeswoman, American Dietetic Association; Oct. 17, 2006, news release, U.S. Institute of Medicine; Oct. 18, 2006, Journal of the American Medical Association; Associatd Press
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