Researchers at UT Southwestern Medical Centre have said that supplements on the market today have labels boasting health benefits that are not supported by clinical data.
The report was published in JAMA Cardiology last month and has already sparked reaction from the Council for Responsible Nutrition (CRN), a trade association representing the dietary supplement and functional food industry.
“About 1 in 5 Americans over the age of 60 take fish oil supplements, often because they think it is helping their heart,” said Ann Marie Navar, member of the Peter O’Donnell Jr. School of Public Health at UT Southwestern, who led the study. “But extensive research has shown that for most people, there is no cardiovascular benefit in taking over-the-counter fish oil supplements, and at high doses, they can even increase the risk of atrial fibrillation.”
Structure/function claims can include statements like ‘supports cognitive health’ or ‘supports healthy joints.’ Technically, these cannot be used to claim that the supplement treats or prevents a disease
- Dr Navar, a board-certified cardiologist
Researchers analysed data from fish oil supplement labels obtained from the National Institutes of Health Dietary Supplement Label Database. Of the 2,819 labels studied, 2,082 (73.9%) made at least one health-related claim.
The majority of supplements with a label making a health claim (80.3%) used what is called a structure/function claim, which is intended to describe in broad terms the effect of the nutrient on a body system.
“Structure/function claims are allowed by the FDA, but they can be vague and misleading,” said Dr Navar, a board-certified cardiologist. “And they are being made for fish oil for a broad number of organ systems, including for the heart, brain, joints, eyes, and immune system. Structure/function claims can include statements like ‘supports cognitive health’ or ‘supports healthy joints.’ Technically, these cannot be used to claim that the supplement treats or prevents a disease, but we feel that this type of language can be very confusing to consumers who may be unaware these statements do not require support from randomized trials.”
Researchers also compared the amounts of two key omega-3 fatty acids – eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – in 255 fish oil supplements from 16 leading brands. In certain patients with very high triglyceride levels (above 500 milligrams per deciliter), these omega-3 fatty acids can be used to lower triglycerides, but a daily dose of 2 grams or more is required.
The study showed that only 24 (9.4%) of the 255 supplements contained a daily dose high enough to lower triglycerides. In addition, there was significant variability in the dosage of EPA and DHA across brands.
“Triglyceride lowering on its own does not prevent heart disease, but some people with very high triglycerides at risk for pancreatitis may be recommended to take fish oil,” Dr Navar said. “In this case, doctors should be specific about the dose of omega-3 recommended, and patients should read the labels carefully to be sure they’re getting the right amount.”
“Supplement labels can be confusing even for the savviest consumers,” said Joanna Assadourian, a fourth-year student involved in the study. “Patients should talk to their doctor about what supplements they are taking and why they are taking them – they may be surprised to learn they are not getting the health benefits they think they are.”
Other UTSW researchers who contributed to the study are Eric D. Peterson, Professor of Internal Medicine and Samuel A. McDonald, Assistant Professor of Emergency Medicine; and Anand Gupta.