A Diner's Guide to Eating Fish Safely

By Timothy Gower

For years, doctors have been begging patients to skip the sirloin and order the salmon now and then. Yet Americans still consume seven times as much red meat as fish. Only about one in five eats the recommended two servings of seafood per week.

Why don't we take the plunge more often? We're confused -- and a little uneasy -- about fish. By now, you've heard that seafood offers far-ranging health benefits, but you've also heard that some fish contain high levels of toxins, leaving you to wonder if any of those gleaming fillets at your grocer's seafood counter are truly safe.

Salmon Entree

Here's the biggest reason medical researchers love fish: It combats the top health threat in the United States. "If you eat a modest amount of fish, you dramatically decrease your risk of dying from a heart attack," says Dariush Mozaffarian, MD, of the Harvard School of Public Health. Findings from 30 large studies conducted around the world show that people who consume just one or two servings of fish per week lower their risk of a fatal heart attack by an average of 36 percent, says Dr. Mozaffarian.

You can thank fish oil, nature's richest source of omega-3 fatty acids, for that cardiac protection. It steadies heart rhythm, lowers artery-clogging triglycerides, appears to cool chronic inflammation in the arteries, and produces a modest drop in blood pressure.

But it's not just your heart that benefits when you dine on sea fare. Your brain does too. Fish lovers suffer fewer strokes, cutting their risk by 40 percent in some studies. And mounting evidence suggests that omega-3 fatty acids help the brain with its normal, day-to-day function. A 2007 study of nearly 12,000 pregnant women found that children born to mothers who ate more than 12 ounces of seafood per week during pregnancy scored six points higher on tests of verbal IQ than kids born to mothers who had other foods on the menu. As for adults, a recent Swedish study found that young men who ate fish more than once a week scored nearly 11 percent higher on IQ tests than males who rarely ate seafood. And in later years, fish eaters appear to be less likely to develop dementia.

As the old commercials used to say: But wait, there's more. Seafood doesn't just keep you in good shape physically; research indicates that people who regularly consume fish oil (either in supplements or at the dining table) are less apt to be depressed. That may be because omega-3 fatty acids raise levels of serotonin and dopamine, two brain chemicals that are thought to play a role in depression, says Joseph Hibbeln, MD, who studies the health benefits of fish at the National Institutes of Health (and who led the 2007 study of pregnant women). Omega-3s also seem to lower levels of brain chemicals that make you feel anxious and stressed-out, Dr. Hibbeln says.

And more advantages may be reported in years to come: Scientists are studying whether fish helps prevent or treat other disorders, from asthma to infertility.

Why You're Concerned

So fish keeps you well physically, mentally, and emotionally. But you may be wondering, What about all the scary things I've heard? Chances are, your biggest concern is mercury: Fish is the leading source of this dangerous element in the human diet.

Fears about fish's mercury levels have gotten a lot of attention in the past decade or so. Indeed, because large doses of the metal can damage developing brains, causing learning difficulties and other problems, the FDA and the EPA issued a joint advisory in 2004 recommending that small children and women of childbearing age eat no more than 12 ounces of seafood per week. The advisory went into some detail because not all fish are equal when it comes to this contaminant: Most species have barely detectable amounts, but large predators can build up high levels over their relatively long lives, since they absorb it from each fish they eat. So the agencies recommended that people in the vulnerable groups limit themselves to six ounces of albacore tuna per week and avoid four very-high-mercury species: swordfish, shark, king mackerel, and tilefish.

Understandably, those warnings caught everyone's attention, not just that of women of reproductive age and parents making tuna sandwiches to put in lunch boxes. Other news didn't help. For instance, a 2002 study in the New England Journal of Medicine found that people with the highest levels of mercury doubled their risk of heart attack (although a second study in the same journal failed to find a link).

Fish Without Worry

So what's a diner to do? Well, eat fish. Drs. Mozaffarian and Hibbeln, and the vast majority of other researchers who've looked at seafood's pros and cons, insist that as long as you take minimal, easy precautions, the health boost you get from fish will far outweigh any risks. In fact, the FDA and the EPA have signaled that they may ease up on their advisory soon, says Dr. Hibbeln, who helped review a new FDA risk-benefit assessment of seafood. In the meantime, here are a number of ways to get a healthy serving of omega-3s while minimizing your intake of mercury.

• Eat fish once a week, but make it oily. A single six-ounce serving of salmon contains barely any mercury yet provides well over the 1,750 mg of omega-3s needed every week to start bringing down your risk of heart disease. (If you pick a leaner fish like catfish, you'll need to eat more of it.)
  
• Eat it often, even if you sidestep a few varieties. The American Heart Association would like you to eat fish at least two times a week; if you want to be cautious, you can go easy on fish higher in mercury, such as grouper and canned white tuna. (It's definitely wise not to go on an eating jag that favors one of the fish high in the metal -- so no matter how much you like tuna steaks, don't dine on them daily.) One reason for reassurance: Two recent studies funded by the EPA suggest that selenium, a trace mineral found naturally in many types of fish, actually protects against the harmful effects of mercury. If further research supports that conclusion, the researchers say, the selenium-mercury balance could provide a reliable guide to low-risk fish.
  
• Take a supplement. If you just can't bring yourself to eat fish, consider taking fish oil supplements. Of course, that means you'd be depriving yourself of a lot of pleasurable eating. We say: Take a look at our buyer's guide and our tips on how to pick and cook fish you'll love -- and dive in.