Fish oil supplements might still not be as good as the real thing

The dietary supplement market in the US is valued at more than $50 million dollars. One slice of that—fish oil supplements—has been growing in popularity in recent years, thanks to the many health benefits touted on their labels. However, medical research has not been able to confirm that consuming the omega-3 fatty acids in them offer many cardiovascular benefits. Despite this lack of hard evidence, fish oil marketers continue to make outsized claims about the supplement’s benefits, according to a study published on August 23 in the journal JAMA Cardiology.

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Fish oil contains two omega-3 fatty acids, EPA and DHA, which are found in flax seeds, walnuts, and fatty fish such as salmon. Higher levels of EPA and DHA have been associated with a lower risk of cardiovascular disease; however, these observational findings are based on patients getting them naturally from their diet and not supplemental use. A 2021 study from the National Institutes of Health also showed that general over-the-counter fish oil supplements do not actually improve cardiovascular outcomes. Additionally, a randomized trial of more than 15,000 patients with diabetes found that the risk of a serious cardiovascular event was not significantly different between participants who were and weren’t taking an omega-3 supplement.

In this new paper, a team from the University of Texas Southwestern Medical Center in Dallas analyzed health claims on the labels of 2,819 fish oil supplements taken from the National Institutes of Health Dietary Supplement Label Database. 

More than 80 percent of the supplements in the study used a structure and function claim. These types of claims vaguely describe the role that omega-3 fatty acids play in the body, like “supports heart, mind, and mood” or “promotes heart health.” 

The study also reviewed qualified health claims and found them on only 19 percent (399) of the labels: 394 relating to coronary heart disease, three for blood pressure, and two relating to both. These claims are related to the supplement’s potential to help in the treatment or prevention of a disease and are made by the US Food and Drug Administration (FDA), but only following an evidence review.

Currently, there are only two cardiovascular-related qualified health claims for fish oil, one that relates to coronary heart disease and the other to blood pressure. In 2019, the FDA wrote, “Supportive but not conclusive research shows that consumptions of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease.”

However, the agency also states that structure and function claims cannot say that a supplement has the power to prevent, treat, or cure any illness or disease. They simply “describes the role of a nutrient or dietary ingredient intended to affect the structure or function in humans.’’

In response to Popular Science’s request to comment on fish oil supplement labels, an FDA spokesperson wrote: “In general, the FDA does not comment on specific studies, but evaluates them as part of the body of evidence to further our understanding about a particular issue and assist in our mission to protect public health. The FDA is reviewing the findings of the paper.”

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“It is true that omega-3 fatty acids are present in the brain and are important for all sorts of brain functions,” study co-author and cardiology professor Ann Marie Navar told The Washington Post. “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.” Navar also added that she was “alarmed” to learn that fish oil supplement labels often include claims that imply health benefits for a wide range of organ systems (brain, heart, and eyes) while conducting the study.

The team did recognize several limitations in their analysis. Companies submit label information to the NIH Dietary Supplement Label Database on a volunteer basis, so the paper was not all-inclusive. What’s more, the authors only assessed supplements from the 16 largest fish oil brands and the health claims on their labels, not promotional materials.

“Nutrition studies are notoriously difficult to conduct in the right way,” certified clinical nutritionist and board-certified holistic nutritionist Megan Lyons told Healthline. “Humans have so many variables at play: different health conditions, diverse dietary intake, varying movement patterns, and distinct sleep and stress patterns—all contributing to our overall health.”