Those omega-3 fatty acid supplements may not deliver on their promise of life-extending health benefits. Here’s your new prescription.
Unfortunately, there may now be a catch. While research in the 1990s initially suggested benefits from dietary fish oil supplementation, new studies—including several high-profile reviews published in trusted journals—no longer support many of the original health claims.
The Health Effects Of Fish
The Bible has anecdotes of people using fish gallbladders to treat blindness. The Spaniards believed fish bile cured madness. And when your grandpa was a pup, he probably had to swallow cod-liver oil to prevent rickets, a bone disorder caused by vitamin deficiency.
Research into the protective health effects of oily fish began around the 1970s, when scientists homed in on polyunsaturated fat intake. That’s when a landmark study from Denmark revealed low rates of coronary artery disease and diabetes among indigenous Greenlanders with a fish-rich diet.
From that point on, the scientific community quickly began building a case for the link between fish consumption and good health.
Later research identified the polyunsaturated omega-3 fatty acids (EPA and DHA, primarily) as the beneficial silver bullet; these are found in high concentrations in such oily fish as sardines, mackerel, and herring. The findings implied that omega-3s from fish lowered blood levels of triglycerides, potentially reducing the risk of conditions like heart disease and cancer.
Additional data over the ensuing decades appeared to support these claims, and by the mid-1990s, the American Heart Association was all in. In 1994, it staged a conference about the therapeutic benefits of omega-3 fatty acids. Supplement companies took notice.
The Great American Shortcut
Americans really don’t do oily fish. Average intake of omega-3-rich fish among U.S. men is a measly 1.4 ounces a week, a 2014 Nutrition Journal study found. Some guys may not like the taste; others might think fish is too expensive, too smelly, or too complicated to cook.
So the supplement industry, sensing an untapped market, decided to address those concerns. The result: a convenient capsule that delivered the goods in one easy swallow. Later the formula was refined to eliminate the fish burps of early omega-3 supplements.
Supplement producers started sending out fleets of warship-size trawlers to harvest omega-3-rich fish. They brought in lobbyists to push legislation that would codify the benefits of fish oil into federal product labeling guidance. Those efforts proved so successful that by 2004, the FDA allowed dietary fish oil supplement labels to state that the capsules may reduce coronary heart disease risk.
The government’s optimism remained guarded, however; the FDA stated that the research was “not conclusive.” But that disclaimer did little to stem the tide of American consumers hungry for omega-3s in a capsule—or companies that were eager to deliver it to them.
What the Original Research Missed
When you look at the entirety of omega-3 research, one thing sticks out: Most of the data on the benefits of omega-3s came from studies that looked at consumption of fish, not fish oil supplements. Only recently have the supplements been studied in a more comprehensive way, and the results raise worrisome questions.
One concern is that over-the-counter supplements may not deliver the fish oil dosage promised on the label. In fact, of 32 commercially available supplements analyzed by researchers in Australia and New Zealand in 2014, only three had levels of EPA and DHA equal to or greater than those advertised on the label. What’s more, two-thirds of the research samples contained less than 67 percent of the EPA and DHA advertised.
So how does this happen? Scientists speculate that in the production process, fish oil may become exposed to the air. This exposure can result in oxidization, reducing the total EPA and DHA concentration of the oil. In fact, some liquid gels contain additional flavorings meant to mask the telltale rancid odor of oxidized fish oil, according to a 2014 report published by Consumer Lab.
“Fish oils, like any nutritional supplement, are not regulated by the FDA the way prescription drugs are, so you can never be quite sure of what you’re getting,” says James Stein, M.D., a professor of cardiovascular research at the University of Wisconsin. That doesn’t necessarily mean they’re dangerous; it just means you might not be getting all you’ve paid for.
“These labels can be confusing,” says R. Preston Mason, Ph.D., who researches omega-3s at Brigham and Women’s Hospital. “They make it sound as though dietary fish oil supplements are some sort of approved omega-3 fatty acid medication, but they’re not. They’re not intended to prevent or treat disease.”