Fish Oil Labels Make Health Claims, Despite Lack of Data

By Marilynn Larkin

Many labels on fish oil supplements make unsubstantiated health claims, and products contain variable daily doses of EPA plus DHA, a cross-sectional study suggests. Overall, about 74% of more than 2800 supplements that were examined had labels that made at least one health claim, and only 19% included a US Food and Drug Administration (FDA)–reviewed qualified health claim (QHC).

The authors say “additional regulation” of the claims may be needed to prevent consumer misinformation. Notably, 20% of adults older than 60 years take fish oil supplements for heart health despite the fact that multiple randomized trials show no cardiovascular benefit.

“Based on what I’ve seen personally in the grocery store and pharmacy, I was not surprised to find such high rates of health claims on fish oil supplements,” lead author Joanna Assadourian, BSA, of UT Southwestern Medical Center in Dallas, Texas, told | Medscape Cardiology. “What was surprising, though, was just how broad the types of claims being made were ― from heart and brain health to joint health, eye health, and immune function.”

Principal author Ann Marie Navar, MD, PhD, also of UT Southwestern, added, “As a preventive cardiologist, I tell my patients that if they are taking fish oil to try to avoid heart disease, then they can stop taking it because it’s not helping them.

“Their money would be better spent on something that will actually prevent a heart attack, like more fresh vegetables, their blood pressure or cholesterol medication, or a gym membership.”

The study was published online August 23 in JAMA Cardiology.

“Vague Statements”

To evaluate health claims made on fish oil supplement labels in the US and to examine doses of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in commonly available formulations, the investigators analyzed labels on supplements obtained from the National Institutes of Health Dietary Supplement Label Database.

The main outcomes were the frequency and types of health claims made on the labels, including the use of an FDA-reviewed QHC vs a structure/function claim and the organ system referenced, as well as the total daily doses in combined EPA and DHA (EPA+DHA) supplements from leading manufacturers and retailers.

QHCs are statements regarding a supplement’s or food’s potential to treat or prevent disease. Such claims undergo evidence review by the FDA and include qualifying language that reflects a lack of scientific consensus or uncertainty.

An example: “Consuming EPA and DHA combined may reduce the risk of CHD [coronary heart disease] by lowering blood pressure. However, FDA has concluded that the evidence is inconsistent and inconclusive. One serving of [name of the food or dietary supplement] provides [ ] gram(s) of EPA and DHA.”

By contrast, structure/function claims “describe the role of a nutrient or dietary ingredient intended to affect the structure or function in humans” but do not state that the supplement prevents, treats, or cures any disease. Such a claim “does not require any mitigating language regarding potential scientific uncertainty of the statement.”

Structure/function claims commonly state that the supplement “maintains,” “supports,” or “promotes” the function of certain organs. Examples are “promotes heart health” and “supports heart, mind and mood.”

Among 2819 fish oil supplements, 2082 (73.9%) made at least one health claim. Of these, only 399 (19.2%) used a QHC; the rest made only structure/function claims. In addition to heart-health claims, many fish oil supplements also have labels that make claims implying benefit to other organ systems, such as brain/mental health, joint health, and eye health ― despite a lack of data from randomized clinical trials that support benefit.

The dose analysis of 255 fish oil supplements across 16 major brands found “substantial variability” in the daily dose of EPA (median [interquartile range (IQR)], 340 [135 – 647] mg/d), DHA (median [IQR], 270 [140 – 500] mg/d), and total EPA+DHA (median [IQR], 600 [300 – 1100] mg/d).

Twenty-four (9.4%) of the supplements contained a daily dose of 2 g or more EPA+DHA.

“Significant heterogeneity exists in the daily dose of EPA+DHA in available supplements, leading to potential variability in safety and efficacy between supplements,” the authors conclude. “Increasing regulation of dietary supplement labeling may be needed to prevent consumer misinformation.”

Navar added, “We now need to understand what consumers are taking away from vague statements like ‘promotes brain health’ or ‘supports joint function’ ― and test what language we can use to accurately describe the state of the science around fish oil and heart health.”


Enthusiasm vs Evidence

“I agree with these concerns and think that the enthusiasm for these supplements outpaces the evidence from rigorous randomized clinical trials,” JoAnn E. Manson, MD, MPH, DrPH, chief of the Division of Preventive Medicine at Brigham and Women’s Hospital in Boston, told | Medscape Cardiology. “Results of the observational studies have tended to be much more favorable than the randomized clinical trials.

“The labels can be very misleading to the general public,” she noted. “People are confronted with a dizzying array of dietary supplements, many of which include structure/function claims that require minimal, if any, evidence of efficacy.

“Clinicians should emphasize with patients that a dietary supplement will never be a substitute for a heart-healthy diet and that many supplements are not helpful for people who already follow a healthy diet,” she said.

The VITAL trial, for which Manson was principal investigator, showed that supplementation with n-3 fatty acids did not lead to a lower incidence of major cardiovascular events or cancer compared to placebo.

A subgroup analysis showed that 1 g/d conferred a 20% reduction in major events only for participants who ate less than 1.5 servings of fish per week, Manson said.

Regarding supplement labels, clinicians should recommend that patients look for a US Pharmacopoeia seal or a seal from the National Science Foundation or ConsumerLab, she advised. These seals ensure that the product has been audited for purity and consistency of content and that the dose in the capsule is consistent with what is on the label.

Manson also would like to see labels explain that most of the products have not been reviewed by the FDA. “Many members of the general public are misled by these labels into thinking that they’re going to receive health benefits. They’re spending a lot of money on supplements that likely provide no benefit and may even be associated with increased risks.”

No funding for the study was reported. Navar has received grants from BMS, Esperion, Amgen, and Janssen and personal fees from AstraZeneca, Boehringer Ingelheim, Bayer, BMS, Esperion, Janssen, Eli Lilly, Merck, Silence Therapeutics, Novo Nordisk, Novartis, New Amsterdam, and Pfizer outside the submitted work and serves as deputy editor for equity, diversity, and inclusion at JAMA Cardiology

JAMA Cardiol. Published online August 23, 2023. Abstract

Follow Marilynn Larkin on Twitter: @MarilynnL.


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