By Katherine Hobson

"Eat fish," the advice so frequently offered by health experts, sounds simple. In practice, it isn't.

When you step up to the seafood counter, you come with an array of priorities that don't always dovetail: promoting heart health, sidestepping contaminants like mercury, and avoiding the purchase of fish produced in an unsustainable way.

A fish that scores high marks in one category may fall short in another. Add in the enormous variety of fish available, and you're in for confusion.

"Fish is so inherently different from any other food," says Tim Fitzgerald, a scientist at the Environmental Defense Fund (New York, NY). "There are hundreds of different species caught or farmed in different ways. For someone who doesn't think about it for eight or 10 hours a day, it's daunting."

Here's a breakdown of the three major considerations:

Eating Fish for Heart Health

The American Heart Association recommends eating fish that contain omega-3 fatty acids, which are linked to improvement in some measures of heart disease risk.

The AHA suggests mackerel, lake trout, herring, sardines, albacore tuna, and salmon as good sources of omega-3s -- but fried or breaded fish does not count.

(Fish is not the only source of omega-3s; plant-based sources, like walnuts and tofu, are also recommended.)

Some researchers say we should be careful to balance the ratio of omega-3s to omega-6s; omega-6s are another class of fatty acids that may help promote inflammation. Alice Lichtenstein, past chair of the AHA's nutrition committee and a nutritional biochemist at Tufts University's Friedman School of Nutrition Science and Policy, says she's not particularly concerned about fish choices based on the omega-3/omega-6 ratio.

"I don't think there are enough data to show we should be concerned," Lichtenstein says. "What's important is that we should all start eating fish."


But there's more to consider than your heart. Mercury and other contaminants, including PCBs, can build up to elevated levels in big fishes that are high on the food chain -- including species like that albacore tuna that is recommended as an omega-3 source. These contaminants are largely a concern for pregnant women and -- because half of pregnancies are unintentional and mercury lingers in the body for a few months -- women of childbearing age, says Emily Oken, a physician and assistant professor in the department of ambulatory care and prevention at Harvard Medical School. It's still unclear, she says, whether contaminants are a significant issue for full-grown adults who aren't or won't become pregnant.

The Environmental Defense Fund has a guide to the maximum number of servings of various fish that can be eaten each month. It also has pocket guides for both regular fish and sushi to help you pick the safest fish.


In addition to concerns about your health, there are concerns about the ocean's. Sustainable fisheries produce species that are "abundant, well-managed, and caught or farmed in environmentally friendly ways," says the Monterey Bay Aquarium's Seafood Watch program, which publishes regularly updated pocket guides for several regions of the country. (You can also get them for your iPhone.)

Such guides are necessary because there are few reliable rules of thumb for choosing the most sustainable fish, says Geoff Shester, senior science manager of the aquarium's Sustainable Seafood Initiative. Some fishing techniques are fine, but others can accidentally snag other species, including other fish and seabirds, or dredge up the ocean floor. And some farms can pollute the environment or allow farmed fish species to escape into the wild and upset the ecological balance; others are contained systems that may actually improve the environment. For example, some shellfish are more sustainable when farmed, but other seafood varieties, like salmon, are always best for Mother Earth when they've been caught in the wild.

And that's where one of the recommendations for omega-3 consumption runs smack up against ecological concerns. Farmed salmon "is one of the best values in fish that are rich in omega-3s," says Fitzgerald. But because it's inherently difficult to farm in a sustainable way, he says, it's on the "avoid" list. (The EDF's and Monterey Bay Aquarium's lists are identical, combining their expertise on contaminants and sustainability.)

So what's a consumer to do?

To get the information you need to make the best choices, you can't be passive. Don't assume that the grocery store has done the filtering for you; at least for now, you can't walk into a big chain, even a Whole Foods or Trader Joe's, and be confident you're being offered sustainable fish only. Talk to the person who sells you fish; you should be able to ask where the fish are from, how they're farmed, and, in some cases, how they're caught.

"They should be comfortable answering that, and you should be comfortable that they're telling the truth," says Fitzgerald.

Best Sustainable, Low Contaminant & Healthy Fish

Here's a list of 11 kinds of fishes that are sustainable, low in contaminants, and high in omega-3s:

1. Wild Salmon From Alaska

Fresh, frozen, or canned are all OK. Wild salmon will cost you a lot more than the farmed variety, but salmon farming practices produce waste and can spread parasites and disease to wild fish, among other problems, according to Seafood Watch.

Calorie count: 211 per 4-ounce serving.

2. Arctic Char

Farming practices for arctic char aren't linked to pollution or contamination, so it's fine to opt for farmed over wild-caught (which isn't as easy to get anyway). At a sushi bar, you may see it called iwana.

Calorie count: 204 per 4-ounce serving.

3. Atlantic Mackerel

Mackerel populations in general are hardy, so wild-caught is A-OK. But because the EDF recommends you limit consumption of the Spanish and king varieties of mackerel because of the potential for mercury contamination, stick to Atlantic mackerel as a staple.

Calorie count: 232 per 4-ounce serving.

4. Sardines

These tiny fish generally come from the Pacific, where the population has resurged. Because they're small, they don't come with the mercury worries of fish higher up the food chain.

Calorie count: 232 per 4 ounces of drained, canned, oil-packed fish.

5. Sablefish / Black Cod

Seafood Watch recommends you stick to fish caught off Alaska and British Columbia, where fishing practices have reduced the likelihood of the accidental catch of other species.

Calorie count: 220 calories per 4-ounce serving.

6. Anchovies

Exact species isn't important; they're all OK, says the EDF. These fish reproduce quickly, so they aren't threatened, and they're small enough so that contamination is not an issue.

Calorie count: 148 per 4-ounce serving.

7. Oysters

Farming operations produce the vast majority of oysters. They are generally well managed and have a low impact on the environment, so farmed oysters are a great choice. At the sushi bar, you may see oysters called kaki.

Calorie count: 67 per 4-ounce serving.

8. Rainbow Trout

Because lake trout in the Great Lakes have been overfished, Seafood Watch recommends farmed rainbow, or golden, trout as the best choice. Because of moderate PCB contamination, the EDF recommends kids limit consumption to two to three meals a month, depending on their age.

Calorie count: 156 per 4-ounce serving.

9. Albacore Tuna

Make sure it's caught from U.S. or Canadian fisheries, which use fishing methods that don't accidentally snag other species. (Most canned tuna comes from fisheries that use more wasteful methods). Kids up to age 6 should limit consumption to three meals a month because of moderate mercury contamination, the EDF says.

Calorie count: 145 per 4-ounce serving of drained, canned, water-packed fish.

10. Mussels

Farmed mussels are raised in an environmentally responsible manner -- in fact, the operations may actually improve the surrounding marine environment. You may see them called murugai at a sushi bar.

Calorie count: 97 per 4-ounce serving.

11. Pacific Halibut

There are lots of different varieties of halibut, but Seafood Watch recommends the wild-caught Pacific (also called Alaskan) variety. Atlantic stocks have declined and are under pressure, and California halibut is caught using less preferable fishing methods. Kids should limit consumption to a few meals a month because of potential for mercury contamination.

Calorie count: 124 per 4-ounce serving.

Which Fish is the Best for Your Health - Healthy Diet

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