I grew up in the beautiful fishing town of Estancia, Iloilo, located in the northeastern tip of Panay, overlooking the Visayan Sea. Thus, as I remember, we always had fish for our meals — seven days a week! Fish was so bountiful at that time, that Estancia was given the monicker the Alaska of the Philippines. Back then, we ate fish because it was readily available and delicious, without much regard for its nutritional value. Today, every day seems to bring more good news about fish, especially its benefits for the heart and brain. But every day, there also seem to be new warnings about contaminants in fish that pose potential health risks. It’s confusing, and as a result, many people are shying away from seafood. That’s not a smart move. There are ways to reel in the benefits of fish while minimizing the risks.
What’s so good about fish? A much-anticipated US government report recently concluded that eating fish may reduce the risk of heart disease. A Harvard report was even more optimistic, stating that eating fish lowers the risk of dying of heart disease by 36 percent. But exactly how is not known. It may simply be that fish, which is low in saturated fat, can replace less healthful foods such as red meat. Or the benefit may be due to fish’s omega-3 fatty acids — “good” fats that may help prevent arrhytmias (irregular heart beats), blood clots, and inflammation, and also help lower triglycerides (fats in the blood). The American Heart Association (AHA) recommends at least two servings of fish a week for heart disease prevention, and higher amounts for people who already have heart disease. Omega-3s are also vital for the brain development of infants and young children, and there’s preliminary evidence that they may help preserve cognitive function in older people, improve mood, treat certain mental disorders, and relieve rheumatoid arthritis and other inflammatory conditions.
Isn’t mercury a problem? Nearly all fish contain mercury, though levels vary widely, even within the same species. Mercury is a heavy metal that occurs naturally in the environment — but much comes from industrial pollution, including coal-fired power plants. When mercury is released into the air, some settle into oceans, lakes, and rivers, where bacteria change it into a toxic form, called methylmercury. As small fish feed on plankton, and larger fish feed on smaller fish, methylmercury accumulates up the food chain; large long-lived predator fish thus contain more mercury. Low levels of mercury may damage the developing nervous system in fetuses, infants, and young children, and there’s debate about whether low levels have negative effects in adults, too. At high levels, mercury can cause neurological and vision problems, and even death.
Should I avoid fish because of mercury? Only women who are or may become pregnant, nursing mothers, and young children are advised to avoid shark, tilefish, swordfish, and king mackerel because of their high mercury levels. In 2004, the US Food and Drug Administration (FDA) and the US Environmental Protection Agency (EPA) advised these high-risk groups also to limit canned albacore (white) tuna and tuna steak to no more than six ounces a week and total fish intake to no more than 12 ounces a week from a variety of sources (young children should eat smaller amounts). Some experts believe, however, that the government’s warnings are not strict enough. Even though the advisories don’t include women past child-bearing years or men, it’s reasonable for everyone to limit exposure to mercury. Fortunately, there are plenty of lower-mercury fish to choose from.
What about PCBs and other contaminants? Fish may also contain PCBs (polychlorinated biphenyls) and other organic pollutants (such as DDT and dioxin). PCBs are banned industrial chemicals that persist in the environment. They are particularly worrisome because they accumulate in the body. It’s not known whether PCBs cause cancer in humans, or how much it would take to cause it, but they do cause cancer and other serious health problems in lab animals. PCBs are likely to show up in fish from lakes and local rivers, but they’re in the ocean, too. Studies have found higher levels of PCBs and other contaminants in farmed salmon than in the wild fish — levels that could be high enough to damage the brains of fetuses and infants, according to EPA standards. Farmed salmon gets PCBs from their feed, a mix of ground-up fish and fish oil. Wild salmon, which has a more varied diet, consumes far less PCBs.
What about fish oil supplements? Most people should eat fish rather than take fish oil (omega-3) capsules because fish contains a range of healthful components that may work together to provide health benefits. Still, people with heart disease or high triglycerides usually need supplements to reach the omega-3 levels recommended by the American Heart Association (see below). Several recent analyses of fish oil supplements found that none contained detectable mercury or unsafe levels of PCBs. But they have other potential problems: High doses increase the risk of hemorrhagic stroke, suppress the immune system, and may raise blood sugar in people with diabetes. And they can cause nausea, diarrhea, belching, and a bad taste in the mouth. You shouldn’t take them if you are on anticoagulants or have uncontrolled hypertension.
WHAT TO DO
Don’t give up on fish. It’s an excellent food, especially if it replaces less healthful protein sources in your diet. The health benefits outweigh any potential risks, especially if you usually choose fish that is low in mercury and PCBs.
The following strategies will help you get the benefits of fish while minimizing your exposure to contaminants:
• Eat fish in moderation — two or three times a week, on average (a serving being four to six ounces) — and vary your choices. Women of childbearing age and young children should follow government advisories (see previous page).
• Good choices are fatty fish lower in the food chain, such as sardines, herring, and anchovies. They provide a lot of omega-3s and are usually good environmental choices.
• To get an idea of your mercury exposure from seafood, including tuna, use the “mercury calculator” provided by the nonprofit Take Action at www.gotmercury.org. It uses government and other data to determine if the fish you eat exceeds safe mercury levels set by the EPA. But note that the results represent averages only; the mercury concentration of individual fish can be much higher or lower.
• If you like salmon, choose the wild variety when available and if you can afford it. Nearly all canned salmon is wild and inexpensive. If you eat farmed salmon, look for South American sources, such as those from Chile. Young children and women who are pregnant or may become pregnant, should eat farmed salmon no more than once a month.
• To reduce PCBs in fish, remove the skin and fat beneath it with a sharp knife before cooking (or ask the fish seller to do it). Broil, bake, or grill the fish on a rack instead of sautéing or frying it. This allows the fat, where the chemicals concentrate, to drain off, but still leaves plenty of beneficial omega-3s. Don’t use butter or breading — that traps the fat drippings. You can also remove the tomalley of lobsters and the “mustard” of crabs, in which contaminants accumulate. No cooking methods can reduce mercury in fish, however.
• The US government lists mercury levels in fish at www.cfsan.fda.gov/-mehg.html. Advisories and other information are at www.epa.gov/mercury/advisories.htm and epa.gov/waterscience/fish/states.htm.
• If you have heart disease, the American Heart Association recommends one gram of omega-3s a day, preferably from fatty fish, or else from supplements. However, before taking omega-3 capsules, consult your doctor. If you have high triglycerides, the AHA advises two to four grams a day from supplements. The FDA has approved a prescription omega-3 product called Omacor for treating high triglycerides. Supplements may also be helpful for rheumatoid arthritis, psoriasis, and other autoimmune disorders; clinical studies suggest about three grams a day.
Keep eating fish. It’s healthy food. And, fish be with you!