Check the labels of various dietary supplements and you’ll likely find they tout a broad range of health benefits. Manufacturers are permitted to say, for example, that a supplement supports a body part or function (like brain health or the immune system).
A new study published August 23 by JAMA Cardiology looked specifically at more than 2,800 unique fish oil supplements and found that the majority of these products carry labels that imply a health benefit for bodily organs, structures, and functions — but lack the scientific trial data to back up their stated effectiveness.
“I worry as a cardiologist that patients may read a statement like ‘promotes heart health’ and wrongly infer that the supplement has been shown to prevent heart disease,” says a coauthor of the study, Ann Marie Navar, MD, PhD, a cardiologist and epidemiologist at UT Southwestern Medical Center in Dallas. “I wouldn’t call any specific claim that we found ‘misinformation’ per se, but I think there is a lot of room for confusion.”
Majority of Health Claims Not Supported by Scientific Evidence
The U.S. Food and Drug Administration (FDA) does not officially approve dietary supplements for any purpose, and supplements cannot state that they prevent, treat, or cure any disease.
Health claims for supplements, however, may be categorized by the FDA as either “qualified” or “structure/function” claims.
Qualified claims describe how the product is supported by scientific evidence, if at all, and include specific language denoting a lack of scientific consensus, per the FDA. An example of a qualified health claim is: “Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease.”
Structure and function claims, on the other hand, describe the role of a nutrient or ingredient on the structure or function of the human body — such as “promotes heart health,” “supports cognitive health,” and “promotes joint comfort and mobility,” according to agency standards.
Fish Oil Supplements Make Many Health Claims
In this latest JAMA Cardiology report, Dr. Navar and colleagues wrote that almost three-quarters (73.9 percent) of 2,819 unique fish oil supplements they investigated made at least one health claim.
Of these, only 399 (19.2 percent) used an FDA-qualified claim, while the rest (80.8 percent) made only structure/function claims.
Marilyn Tan, MD, an endocrinologist and a clinical associate professor of medicine at Stanford University in California, urges the public to be wary about such health assertions, stressing that generally there are no vigorous clinical studies to support the efficacy and safety of dietary supplements.
“Many of the claims are very vague, alluding to key terms that catch people’s attention, such as ‘aging,’ ‘vitality,’ ‘immune support,’ and ‘cellular support,’” says Dr. Tan, who was not involved in the new research. “Claims related to structure/function should not be taken as a proven effect in vivo [in the living human body]. Many structural and functional claims do not pan out in real world or clinical settings.”
There is some limited evidence that fish oil supplements improve certain conditions. Clinical trials have shown, for instance, that omega-3 supplements perform slightly better than placebo for symptoms of depression and attention deficit hyperactivity disorder. To see improvement in hair, skin, or even memory, though, studies suggest it may be better to just eat more fish.
Omega-3 Fatty Acid Content Substantially Differs Depending on the Supplement
Fish oil contains two omega-3 fatty acids that play an important role in heart and brain health, according to the American Heart Association (AHA).
This new research, however, found that amounts of these fatty acids — EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) — greatly vary among the different fish oil supplements.
Scientists noted that a minimum daily dose of 2 grams (g) of EPA and DHA may help lower triglycerides, a type of fat in the blood.
Of 255 fish oil supplements evaluated for EPA and DHA, only 24 (9.4 percent) contained that minimum level or more.
“As a cardiologist, I sometimes recommend fish oil supplements for people with high triglycerides,” says Navar. “But at this [2 g] dose, the risk of atrial fibrillation may be increased, so fish oil is not what I consider first-line for high triglycerides. We have other, better, and safer medications available.”
Talk to Your Doctor Before Taking Supplements
Patients often want to take supplements as a more “natural” way to improve their health, according to Dr. Tan, but she cautions that misleading claims may lead to dangerous outcomes and calls for more regulation.
“It’s important to review all supplements and their contents with your healthcare providers, and it’s critical not to use a supplement to replace a medication prescribed by your healthcare provider,” she says.
As far as Navar is concerned, most patients may be better off avoiding supplements entirely.
“Based on my clinical experience, a lot of people are spending money and effort to take pills that they think are helping them but that really are not,” she says.