While it’s true people who eat seafood regularly are less likely to die of heart disease, studies have not shown that taking fish oil as a supplement offers the same benefit. Even so, fish oil marketers continue to make health claims that imply a wide range of benefits, according to a study published Wednesday in JAMA Cardiology.
The researchers analyzed labels from more than 2,000 fish oil supplements that made health claims. They found more than 80 percent used what is known as a “structure and function claim,” which is a general description that describes the role of omega-3 fatty acids in the body — such as “promotes heart health” or “supports heart, mind and mood.” Cardiovascular health claims, which accounted for 62 percent, were most common.
Fish oil contains two omega-3 fatty acids, EPA and DHA, found naturally in fatty fish such as salmon. Higher levels of these omega-3s have been associated with a lower risk of cardiovascular disease, but the observational findings are based on omega-3 levels in the diet, not from supplement use, some experts say. In fact, two recent large clinical trials showed that over-the-counter fish oil supplements do not improve cardiovascular outcomes.
But the vagueness of the wording used by fish oil marketers could lead to misinformation about the role of the dietary supplement, said Ann Marie Navar, associate professor of cardiology at the University of Texas Southwestern Medical Center, who was senior author of the study.
“It is true that omega-3 fatty acids are present in the brain and are important for all sorts of brain functions,” she said. “What has not been consistently shown with high-quality trials is that taking more of it in the form of a fish oil supplement leads to improved performance or prevention of disease.”
Fish oil claims not supported by science
Navar said she and her colleagues decided to make an inventory of the claims made on fish oil supplement labels after she was continually hearing from her patients that they were taking it for the heart health benefits — and then seeing their surprise when she advised them that there probably are none.
Through her research, Navar said, she was “alarmed” to learn that fish oil supplement labels often include claims that imply health benefits for a wide range of organ systems, including the heart, brain and eyes.
“It’s not surprising to me that my patients think fish oil is helping them,” she said.
Previous research has shown “conflicting results” on whether fish oil supplements are beneficial for heart health, and in recent years, new scientific data has cast further doubt.
In a randomized trial of more than 15,000 patients with diabetes — a risk factor for cardiovascular disease — the risk of a serious cardiovascular event was not significantly different between those who were taking an omega-3 supplement and those who were not.
Another randomized trial, which included more than 25,000 participants, showed that supplementation did not reduce the risk of experiencing a major cardiovascular event or getting cancer.
Omega-3s from diet, not supplements
The fact that fish oil supplement manufacturers are implying — though not promising — a variety of health benefits is concerning given that the evidence does not support them, said Luke Laffin, a preventive cardiologist at Cleveland Clinic, who was not involved in the study.
“If we really thought people benefited from it, we would be prescribing it,” he said.
Laffin said he encourages his patients to get their omega-3 fatty acids from their diet. Fish such as salmon and mackerel, flaxseed, and chia seeds are rich in omega-3s, and he said eating them is part of a healthy dietary pattern, which is “a very important thing when we think about cardiovascular health.”
“As cardiologists, we want people to take the appropriate medicine and not take things that are not going to help them,” he said.
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