Fish Oil Supplements: Truth in Advertising?

Despite multiple randomized trials showing no cardiovascular benefits to fish oil supplements, they are taken by millions of U.S. adults, many of whom believe they are deriving some sort of health benefit. One area where consumers may receive misinformation about the benefits of supplements is on the labels themselves.

At #AHA22, one of us (JA), a third-year UT Southwestern medical student, presented a study concerning two aspects of fish oil supplements: first, the claims of health benefits reported on the labels of the health supplements, and second, whether the doses of the supplement mirrored the doses shown to have health benefits.

We systematically evaluated the health claims made on all n=2,819 on-market fish oil supplements in the U.S. Dietary Supplement Label Database, and the doses of EPA and DHA for the n=255 fish oil supplements made by the 16 largest retailers/manufacturers in the U.S.

More than 75% of labels made at least one health claim. While there is FDA-approved language for two different “qualified health claims” for fish oil, this language was rarely used. Rather, most labels made vaguer claims considered “structure and function claims” such as “promotes heart health” or “supports brain function.” Cardiovascular health-related claims were the most common, present in 62% of labels, though a range of other health claims were also made, including brain health, joint and musculoskeletal benefits, and other areas such as “immune support.”

Regarding dosing, substantial variability was seen both between and within manufacturers in the total and relative amounts of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). However, only 7.1% of supplements contained ≥ 2 gm of EPA+DHA, the minimum recommended dose for triglyceride lowering, and none contained an EPA dose shown to prevent cardiovascular events (≥ 4 gm/day).

We believe that doctors need to know that most available fish oil supplements do not contain sufficient EPA and DHA to lower triglycerides, and consumers need to be aware that many of the statements made on these labels that imply a health benefit are not supported by any data.