Having been urged to eat fish for health reasons, many shoppers are now concerned that the benefits could be outweighed by an alarming downside — the recent reports of toxins discovered in several species. In this “Today” 101, food editor Phil Lempert looks at which fish you should eat, and how often.
Just last week, the U.S. Dietary Guidelines Advisory Committee released its long-awaited recommendations to the U.S. Department of Agriculture and the Department of Health and Human Services.
On the positive side, the report recommends that fish should be eaten at least twice a week (12 ounces total) in order to get enough Omega-3 fatty acids. The reason for this recommendation is that many studies over the past few years have shown that Omega-3s, which are prevalent in certain types of fish, provide a multitude of health benefits, from heart disease prevention to battling depression to making our skin firmer and more youthful.
However, recent studies and Food & Drug Administration warnings have made consumers concerned about dangerous levels of mercury, dioxins, PCBs and other toxins, according to reports on salmon, swordfish, shark, ahi and even canned tuna. This has left many shoppers confused about which fish to eat, and how often.
Topline on Fish ToxinsFatty fish such as salmon, mackerel, shark, swordfish, and herring are the most likely to contain dangerous chemicals in their fat tissues. But not all fish are created equal — nor are the toxins. A good rule of thumb to follow is that the larger the fish, the greater potential for toxicity since these fish have been swimming and feeding longer.
Dioxins are a by-product of some industrial processes as well as household fires. According to the FDA, studies have shown that exposure to dioxins at high enough doses may cause a number of adverse health effects. Because dioxins exist throughout the environment, almost every living creature, including humans, has been exposed to dioxins.
The most common health effect in people exposed to large amounts of dioxin is chloracne. Chloracne is a severe skin disease with acne-like lesions that occur mainly on the face and upper body. Other effects of exposure to large amounts of dioxin include skin rashes, skin discoloration, excessive body hair, and possibly mild liver damage.
The FDA also reports that several studies suggest that workers exposed to high levels of dioxins at their workplace over many years have an increased risk of cancer. Animal studies have also shown an increased risk of cancer from long-term exposure to dioxins.
PCBs (polychlorinated biphenyls) are among the chemicals of most concern. Although outlawed in the 1970s, their residue still pervades our environment. PCBs, a pollutant created mainly in the production of electrical equipment, have been demonstrated to cause a variety of adverse health effects, including cancer in animals. PCBs have also been shown to cause a number of serious non-cancer health effects in animals, including effects on the immune system, reproductive system, nervous system and endocrine system. Studies in humans provide supportive evidence for potential carcinogenic and non-carcinogenic effects of PCBs.
PBDEs (also a polychlorinated biphenyl) are fire-retarding chemicals used in industrial processes. Their use has been banned, but they are still routinely added to computers and other electronic items around the world. Scientists say PBDEs can harm neurological development and function in babies and young children, and that long-term effects may include cancer, liver damage and thyroid-gland dysfunction. The impact on people and the harmful levels required to do such damage is still being debated.
Mercury is the toxin that most shoppers are familiar with. Fish can harbor mercury, a metal that accumulates in the bodies of fish-eaters and can damage the growing brains of fetuses and young children. The paradox is that fish also contains certain fats, the aformentioned Omega-3 fatty acids, that are heart-healthy and important for fetal brain development. About 8 percent of U.S. women of childbearing age have enough mercury in their blood to put a fetus at risk.
The FDA and EPA recommend that at-risk people, such as pregnant women, women who might become pregnant, nursing mothers and young children, do NOT eat shark, swordfish, king mackerel or tilefish because they contain high levels of mercury. Five of the most popular fish that are low in mercury are shrimp, canned light tuna, salmon, pollack and catfish.
So, why should we eat any fish?Omega-3 fatty acids are important for normal growth, especially for blood vessels and nerves. They also help keep our skin and other tissues youthful and supple. Research studies have shown that in populations that consume large quantities of fish, with a high consumption of Omega-3s, there is a reduced risk of heart disease.
As of now, there is no recommended daily allowance for Omega-3s, but studies show that consuming two servings a week of fish does offer health benefits. However, because of the mercury content in fish, it is also recommended that consumption be limited to two to three servings a week, especially among children and pregnant and nursing women since they are at higher risk of suffering from mercury toxicity, according to the American Heart Association.
Is there anything we can do?
Yes. Buy and consume fish that has low levels of mercury and other toxins. In addition, when preparing fish at home, follow these recommendations from the Illinois Department of Natural Resources:
- Trim away fatty areas such as the belly, top of the back and dark meat along the sides.
- Remove or puncture the skin before cooking to allow the fat to drain off.
- Broil, grill, roast or steam the fish on a rack to allow the fat to drain away.
- Do not fry large fatty types of fish such as salmon or bluefish.
- Throw away fatty drippings: don’t use them in other cooking.
How the fish in your market rates
Salmon is now America’s third most popular fish — canned tuna is number one and shrimp number two — fueled in large part by lower prices made possible by fish farming. Over the past few months, however, studies have shown that many people have made the switch from farm-raised salmon to wild salmon in order to avoid the contaminants that were discovered and made public by the Environmental Working Group earlier this year. (In August, though, a study conducted by Indiana University found that both wild and farmed salmon from around the world tested positive for PBDEs.) And, while the EPA has recommended a cutback in farm-raised salmon consumption to one 8-ounce serving per month, the FDA has not gone along.
Part of the objection to farm-raised salmon is that it is artificially colored. It isn’t naturally pink — it’s gray. Wild salmon is pink because of its diet, which is different than what is fed to the farm-raised variety. The farmed-fish industry says that the pigments added to farmed fish food are synthetic versions of what naturally occurs in nature.
Nutritional overview: Salmon (wild)
Based on a 3.5 ounce servingCalories: 233
Total Fat: 13.4g
Nutritional overview: Salmon (farm-raised)
Based on a 3.5 ounce servingCalories: 203
Total Fat: 11.9g
Toxic Topline Studies have shown that farm-raised salmon has significantly higher concentrations of PCBs and dioxins than does wild salmon. Mercury levels in both varieties, according to EPA and FDA reports, are low.
Consumption recommendation: Eat no more than one 8-ounce serving of farm-raised salmon a month and four to six servings of wild salmon a month.
TUNASales of canned albacore tuna have dropped 9.7 percent since the FDA advisory on mercury was released, according to “Seafood Business” magazine.
Nutritional overview: Fresh tuna (cooked)
Based on a 3.5 ounce servingCalories: 182
Total Fat: 6.18g
Omega-3s: 1.75 grams
Nutritional overview: Canned tuna (chunk light)
Based on a 3.5 ounce servingCalories: 115.5
Total Fat: .46g
Omega-3s: 0.58 grams
Nutritional overview: Canned tuna (white albacore)
Based on a 3.5 ounce servingCalories: 123
Total Fat: 1.75g
Omega-3s: 0.58 grams
Toxic ToplineAccording to the EPA, tuna steaks generally contain higher levels of mercury than canned tuna. Chunk light canned tuna contains about one third less mercury than white albacore.
Consumption recommendation: Tuna steak, up to 6 ounces per week. Canned tuna, up to two servings a week (chose chunk light over white albacore).
SWORDFISHSwordfish is on the EPA “do not eat” list for pregnant women, women who might become pregnant, nursing mothers and young children because it contains high levels of mercury.
Nutritional overview: Swordfish (cooked)
Based on a 3.5 ounce servingCalories: 164
Total Fat: 5.4g
Omega-3s: 1.057 grams
Swordfish has among the highest levels of mercury, and the FDA and EPA says that at-risk groups should avoid this fish at the present time.
Consumption recommendation: Pregnant women, women who might become pregnant, nursing mothers and young children should not eat swordfish.
FLOUNDER and TILAPIA
Both of these fish, the former wild and the latter farmed, contain low levels of mercury and other contaminants, and are high in nutritional value.
Nutritional overview: Flounder (cooked)
Based on a 3.5 ounce servingCalories: 115
Total Fat: 1.48g
Omega-3s: 0.407 grams
Nutritional overview: Tilapia (cooked)
Based on a 3.5 ounce servingCalories: 95
Total Fat: 1g
Omega-3s: 2.56 grams
Toxic ToplineBoth of these fish contain among the lowest levels of mercury and any other toxins.
Consumption recommendation: Up to two servings a week of either tilapia or flounder (or sole).
As well as containing low levels of mercury and other toxins, trout has very high nutritional values.
Nutritional overview: Farmed trout (cooked)
Based on a 3.5 ounce serving
Total Fat: 7.1g
Omega-3s: 1.37 grams
Toxic ToplineBoth farm-raised and fresh-water trout contain among the lowest levels of mercury and any other toxins.
Consumption recommendation: Up to two servings a week.
HALIBUTThis popular fish, generally from Arctic waters, is low in toxins and high in nutrition.
Nutritional overview: Halibut (cooked)
Total Fat: 1.9g
Omega-3s: 0.349 grams
Halibut is on the “lowest mercury levels” list, but has a higher concentration of mercury than tilapia, salmon, flounder or sole.
Consumption recommendation: Up to two servings a week
SARDINESThough low in mercury, this fatty fish contains high levels of other toxins.
Nutritional overview: Sardines (Atlantic, canned in oil, drained solids with bone, 2 sardines [24g])Based on a 3.5 ounce servingCalories: 206.25
Total Fat: 11.3g
Omega-3s: 2.3 grams
Sardines have their own paradox: very high in calcium due to their bones, rich in Omega-3s, low in mercury — but high in PCBs and other toxins.
Consumption recommendation: The Environmental Working Group suggests avoiding sardines due to the high level of toxins.
Phil’s Bottom LineIt is important not to overreact to the news about contaminants in fish. Overall, fish is good for us and is an important part of a healthy diet. Instead, eat those fish that are lowest in contaminants, such as cod, haddock, tilapia, flounder and trout. According to both the FDA and EPA, limit overall fish consumption to two servings (12 ounces) a week to minimize exposure to mercury. At-risk groups, such as pregnant women, women who might become pregnant, nursing mothers and young children, should avoid those fish on the “do not eat” list: shark, swordfish, king mackerel and tilefish.
The FDA tests fish for mercury and publishes it on their Web site: .
The EPA has set a safe maximum weekly intake for mercury of 38.5 micrograms for a 120-pound person. To calculate the maximum level for you, multiply your weight by 0.32 times the mercury levels listed by species in the FDA’s report.
Phil Lempert is food editor of the “Today” show. He welcomes questions and comments, which can be sent to