The good news is that more Americans are eating salmon, gobbling up its heart-friendly omega-3 fatty acids and making it the third most consumed fish behind shrimp and tuna.
The bad news is that a recent study warns against the high levels of PCBs in farmed salmon. Fortunately, most health experts are telling us to go ahead and eat it anyway.
Let’s sort it out.
A study funded by the Pew Charitable Trusts, published in the journal Science this month, made front page headlines (including in this newspaper) warning that farmed salmon have much higher concentrations of polychlorinated biphenyls (PCBs) and other contaminants. About 60 percent of the salmon Americans eat come from fish farms, mostly from farms in North and South America–which have the lowest contamination levels, according to the study. European farm-raised salmon (such as fish from Scotland or the Faeroe Islands) had the highest.
Opinions vary widely regarding the safety of eating farmed salmon. Experts in the Science study, along with government agencies, aren’t advocating that you stop eating the tasty fish. The hardworking essential nutrients of omega-3s have been shown to improve heart health. In addition to lowering cholesterol levels, omega-3s help ease headaches, cramps, arthritis and other inflammatory diseases.
One reason to not immediately reject salmon is that this fish has more of the type of omega-3s we need. Not all omega-3s are alike–there are short chain and long chain–and we need both. It’s the long chain variety, however, that researchers say are responsible for the health benefits. Short chain omega-3 fatty acids come from some plant sources, and these plant-based omega-3s turn into long chain in the body, but their power gets lost in the translation.
“Sources such as flax seeds, walnuts, pumpkin seeds and black currant seed oil have the highest amounts of omega-3s in the plant family but they are short chain,” says Kate J. Claycombe, an assistant professor at Michigan State University’s food science and human nutrition department and the cell and molecular biology program. “The health benefits of long chain fatty acids available from salmon and mackerel are far greater.”
The benefits are so highly regarded that health officials still stand by salmon. The American Heart Association holds that eating oily fish like salmon, tuna or bluefish at least twice a week can prevent sudden cardiac death because the fatty acids in the fish block dangerous irregular heart rhythms. The association’s position remains unchanged despite the study.
Unwanted byproducts
PCBs and other toxins are a part of modern life and will be so for a very long time. Though production of these chemicals ceased decades ago, they remain in our food chain, albeit at very low levels. And they’re not just in fish; PCBs, which are concentrated in fats, have been found in beef, pork, poultry and milk.
But fish, particularly farmed salmon, show some of the highest concentrations of PCBs, according to the Environmental Working Group (EWG), which released a salmon study in July. Its findings concur with those of the Pew-funded study, although the latter included far more specimens: some 700 whole salmon or fillets.
Farmed salmon eat an abundance of oil-laden fish meal, which in itself can be contaminated with PCBs. Further, most farmed salmon are raised in crowded cages and don’t get much exercise swirling around in a pen, according to the EWG. Compare that to their wild counterparts that hunt and eat a variety of food. Farmed salmon can be as much as 30 percent fatter than wild salmon and hence have higher contaminant levels.
How much is too much?
While it’s true that farmed salmon can have more PCBs than wild, how much is really harmful?
“Dose makes the poison,” says Charles Santerre, a toxicologist at Purdue University, who believes that the health benefits of eating salmon outweigh the risks named in the studies. The U.S. government concurs. Health officials and dietitians say they want us to eat the salmon because the good really does outweigh the bad.
Trace amounts of PCBs, say government agencies, are safe. PCBs are measured in parts per billon. The FDA, which regulates commercial salmon, says no more than 2,000 per billion. The EPA, which regulates recreationally caught wild salmon, sets the limit at 4 to 6 parts per billion. Quite a range. The EPA figures were updated in 1999, while the FDA bases its guidelines on 1984 research.
Also, figures are based upon raw salmon. Cooking salmon will reduce PCB levels by 30 percent to 50 percent, Santerre says.
Claycombe, however, adds a note of caution. “Fish may have other contaminants such as mercury, dioxins, DDT and chlordane,” she says. “Processing by heat or cooking may not reduce all of these other harmful agents.”
So what’s an omega-3 health conscious salmon lover to do? The EWG recommends that consumers choose wild salmon when possible. “And if you eat farmed salmon, eat it once a month, skin it and grill, bake or broil to reduce the fat,” says Lauren Sucher, EWG communications director.
Shopping for salmon
Many restaurants and grocers label their salmon “wild” or “farmed,” and there are different types of salmon available (e.g. king, silver and sockeye). Season and price will generally tell you what’s what: Wild salmon is two to three times more expensive than farmed and it’s in season roughly May through October. Also, most Atlantic salmon is farmed, because there is little left in the wild. Pacific salmon can be farmed or wild. Interestingly, canned salmon, which generally sits right next to the canned tuna in stores, is most often wild Alaskan salmon.
Markets and seafood stores carry fresh wild salmon in season. You’ll find farmed salmon readily available in most grocery stores year-round. Check the labels–and remember, Chilean and North American farmed salmon have lower levels than the European variety.
If you see fresh salmon on a restaurant menu in the dead of winter, it is likely farmed, unless it has been frozen for a while. “Fresh” doesn’t necessarily mean wild; it may simply mean not frozen. Inquire to know what you’re getting.
