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The new line on fish
Is seafood safe? In 2004, the FDA warned the public about risks, but for most people, eating fish is a net gain.
From staff and wire reports
Just when you thought the health benefits of fish weren't worth some of the risks, along comes this message, courtesy of two new major studies: Take the plunge. Eat fish.
Health-conscious consumers have worried that the toxic substances, such as mercury, contained in some seafood could cancel out any potential good that could be done. But the two federally funded studies released recently have weighed the evidence and come down on the side of fish.
The reports -- one from the Institute of Medicine and the other from Harvard Medical School, Harvard School of Public Health and Brigham and Women's Hospital in Boston -- analyzed hundreds of studies and determined that eating seafood may help reduce the risk of heart disease in the general population.
Both reports also assessed the risks of eating seafood -- including exposure to toxic chemicals such as methylmercury, polychlorinated biphenyls (PCBs) and dioxins -- and decided that the evidence of adverse side effects for the general public is inconclusive. (Certain groups, including pregnant women and children under 12, should still steer clear of certain kinds of fish, however.)
But how much is enough -- or too much? Which kinds can you eat, and who can eat them? And what really are the risks and benefits? Here's a rundown on what fish aficionados need to know:
Tell me again why I should be eating fish.
Doctors tout fish as a strong source of lean protein. Fatty fish, such as salmon or albacore tuna, is recognized as an important source of two kinds of omega-3 fatty acids -- eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), "good" fats that help prevent higher blood pressure and irregular heartbeats, both of which can lead to heart attacks. The American Heart Association recommends that people eat fish -- particularly the fatty type -- at least twice a week.
So what's the problem, then?
In March 2004, the U.S. Food and Drug Administration and the U.S. Environmental Protection Agency issued a joint advisory on methylmercury in fish. Although it stated that fish and shellfish are important components of a healthful diet, it warned women who are pregnant, nursing or planning to become pregnant to avoid types of fish that contain high levels of mercury. Methylmercury can cause permanent neurological damage in infants and fetuses.
Oh, and on top of that, most states have issued advisories warning of the toxic substances found in fish caught locally -- including mercury and PCBs, industrial chemicals banned since the 1970s that persist in the environment and that have long been suspected of causing cancer and reproductive problems.
Oh. I see. It's kind of confusing.
Yes, it is. Hundreds of previous studies were examined by the two organizations making the new reports.
What are some of the major points made by the new studies?
For the Harvard report -- "Fish Intake, Contaminants, and Human Health," supported by the National Institutes of Health and published in JAMA, the Journal of the American Medical Association -- the researchers pooled the data of more than 200 existing studies. These studies investigated the benefits of fish and fish-oil consumption on cardiovascular health in adults and on the neurological brain development of babies, as well as the health risks of methylmercury, PCBs and dioxin found in fish.
The authors of the Harvard report are explicit in their conclusion: The benefits of modest seafood consumption far outweigh the potential risks. In their analysis, the researchers looked at a wide variety of commonly consumed fish. They determined that the cardiovascular health benefits of wild-salmon consumption, for example, outweigh the cancer risks by 900 to one, while the benefits of farm-raised salmon outweigh the risks by 300 to one.
The Institute of Medicine report -- "Seafood Choices: Balancing Benefits and Risks," sponsored by the National Oceanic Atmospheric Administration with support from the FDA -- is more measured in its findings, which weren't based on pooled data but on the qualitative examination of hundreds of studies. The report determined that people may be able to reduce the risk of heart disease by eating seafood, although it isn't clear if this is because of the protective effects of omega-3 fatty acids or because substituting the lean protein of fish for a fatty cut of meat reduces one's intake of saturated fat.
Is this the last word on the subject, then?
Not at all.
The Institute of Medicine report concluded that much of the scientific evidence for both the benefits and the risks of seafood is preliminary or insufficient.
It says there aren't enough reliable data about contaminants and little evidence of how the beneficial effects of seafood may counteract some of the risks. It determined that people who have already had heart attacks may not necessarily reduce their risk of future attacks by eating fish, as previously thought. It also decided that it is unclear whether seafood can reduce a person's risk for other diseases, such as diabetes, cancer or Alzheimer's.
What are some specific benefits that can be gained from eating fish?
Researchers at Harvard found that people who eat one to two servings of fish per week -- especially varieties higher in fatty oils, such as wild salmon -- may reduce their risk of death from heart attacks by 36 percent and the rate of death in general by 17 percent.
In addition, both reports found that fish consumption by pregnant or nursing women (a population that has recently been skittish about consuming fish) may have a beneficial effect on their infants, including improved visual acuity and cognitive development.
How much should I be eating, then?
Healthy adolescent males, adult males and females who won't become pregnant should aim for two 3-ounce servings per week.
People who consume more than two servings per week should make sure they are eating a variety of types of seafood, to diminish their risk of exposure to contaminants from a single source.
What about women of childbearing age?
Because of the risks associated with methylmercury in fish, women who are or may become pregnant or who are breast-feeding should avoid certain types of fish. These include shark, swordfish, tilefish and king mackerel. They should also limit their intake of albacore, or white, tuna; it has higher mercury levels than "light" tuna.
However, these women may also benefit from eating other types of seafood, especially fatty varieties that are relatively higher in omega-3 fatty acids. The Harvard study says that women in this category should aim for up to 12 ounces of fish per week, while the Institute of Medicine report says that two servings of 3 ounces each would be sufficient, although up to 12 ounces is safe.
And for kids?
The Institute of Medicine report also said children up to age 12 can eat two 3-ounce servings per week (or an age-appropriate size), and they can safely consume up to 12 ounces per week.
However, the studies also assert that children younger than 12 should steer clear of the same fish pregnant and nursing women should avoid --shark, swordfish, tilefish and king mackerel. They, too, should limit their consumption of albacore.
Give me some specific examples of fish I should be eating.
Oceans Alive, part of the Environmental Defense Fund, maintains a list of seafood recommended, or not recommended, on the basis of health risks and health benefits, as well as on the basis of risks to the environment. (Find it at www.oceansalive.org.)
Among those considered safer choices by the group: crawfish, herring, blue mussels, sardines, sockeye salmon, pink salmon, bay scallops and tilapia.
Among those on the "health concerns" list: orange roughy, monkfish, bluefin tuna, Atlantic farmed salmon and grouper.
Can some of the risk from toxins be reduced by the way I cook my seafood?
Mercury levels in seafood cannot be lowered by cooking methods or by skinning or trimming fish. In fact, the concentration of mercury in cooked fish can be higher than in raw fish.
However, because PCBs, dioxins and pesticides are concentrated in fat, you can reduce the risk of exposure to some of these chemicals with these steps:
Remove skin, fat, organs and innards such as the mustard of crabs.
Do not use fish drippings in sauces.
Avoid fried fish, which can "seal in" the toxins in the fat of the fish. Low-fat methods of cooking, such as broiling, let more fat escape into the pan.
This report contains material by Elizabeth Bernstein of The Wall Street Journal.
ADDITIONAL SOURCES: American Heart Association; Oceans Alive, a program of the Environmental Defense Fund; United States Environmental Protection Agency
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