Research Finds That Most Fish Oil Supplements Make False Health Claims

The majority of fish oil supplements sold in the U.S. make health claims that may not be supported by scientific evidence, a new study finds.

Fish oil is one of the many supplements making its way around health food stores, with consumers often sharing their success stories with the product online. While there are a variety of health claims around fish oil, a positive impact on the joints, eyes, heart, and skin are among the common benefits discussed.

But anecdotal evidence doesn't equate to scientific research.

A group of researchers out of UT Southwestern Medical Center (UTSMC) in Dallas, TX sought to clear up consumer confusion around whether or not fish oil positively impacts heart health.

Ann Marie Navar, MD, PhD, the study author and an Associate Professor of Cardiology at UTSMC, told Health that despite consumer confidence in fish oil, there is little clinical data to confirm its benefits for most people’s heart health.

“The science in this area has evolved considerably—epidemiologists first found that people who eat more fish and who have higher levels of EPA and DHA in their blood have less heart disease,' Navar said. 'This led people to think there could be a benefit to fish oil.'

She explained that this early data even prompted the FDA to approve a qualified health claim in 2003 that fish oil may lower the risk of coronary heart disease.

“Unfortunately, several large, high-quality, placebo-controlled randomized trials done since that time have failed to show any benefit for fish oil supplementation in the general population for prevention of heart disease,' she said.

Still, many supplement companies continue to manufacture fish oil pills and liquids that make claims about their positive effects on heart health. The study found that though these claims are technically legal, they are largely inaccurate.

“Given how often these... claim types are used, we [felt] more research [was] needed to better understand how consumers are actually interpreting these types of statements,” study co-author and fourth-year UTSMC medical student Joanna Assadourian told Health.  

Ultimately, research like this could lead to increased regulation from the FDA or other public health organizations to prevent consumer misinformation.

Although supplement manufacturers are not legally allowed to state that fish oil (or any other dietary supplement) “prevents” or “treats” disease, more subtle claims persist on packaging.

“Statements like ‘promotes’ or ‘supports’ heart health are considered ‘structure and function’ claims, which are allowed under current regulations and do not require randomized trial evidence to support,” Assadourian said.

The researchers didn't have a hard time finding examples of these claims.

Among the 2,819 unique fish oil supplements examined, 2,082 (73.9%) made at least one health claim. Of these, 399 (19.2%) used an FDA-approved qualified health claim, while the rest (1,683 or 80.8%) made only structure/function claims like “promotes heart health.”

Cardiovascular health claims were the most common, printed on 62% of fish oil labels. 

In addition to varying health claims, the researchers found that dosage varied widely among fish oil supplements.

In 255 fish oil products across 16 leading brands, there was substantial variability in the amount of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the two active ingredients in fish oil. The amount of EHA ranged from 135-647 milligrams per dose, while DHA ranged from 140-500 milligrams.

As for what constitutes the proper dose of fish oil, Navar is skeptical.

“Zero milligrams—I advise my patients to save their money,” she said. “Fish oil nutritional supplements do not prevent heart attacks or strokes in the general population.”

Printed claims and a popular reputation have created a “health halo” around fish oil and its supposed benefits for cardiovascular well-being. Yet experts say taking fish oil for heart health is a largely unfounded practice.

“There have now been a large number of well-conducted studies which have not shown a cardiac benefit to taking over-the-counter fish oil supplements,” Timothy Jacobson, MD, chief cardiologist for Kaiser Permanente in the Northwest, told Health. 

In fact, Jacobson said, taking fish oil could even have adverse effects for some people. “There is data these supplements may increase the risk of atrial fibrillation,” he said.  

There is one group of people who might be an exception—those with very high triglycerides.

A large 2019 study in the New England Journal of Medicine found that a high dose of EPA fish oil reduced elevated triglycerides, as well as decreased the risk of heart attack and stroke.

“For people who have extremely high triglycerides…at least 2 grams of combined EPA and DHA is recommended,' Navar said, 'but in this case, there are safer and more reliable ways to lower triglycerides than fish oil.'

Prescription-strength preparations exist that provide 2 or more grams of EPA and DHA, but Navar said these medications were outside the scope of her research. Only 24 of the 2,082 fish oil products studied had 2 grams or more of this combination of ingredients.

As this new research shows, dietary supplements may make all sorts of claims that lead you astray. Instead, talk to a doctor or a registered dietitian about which supplements (if any) have evidence-based benefits for your individual heart health concerns.

You might be surprised at their answers.

While Jacobson doesn't routinely recommend fish oil, there are other supplemental nutrients he says can boost heart health. These include omega-3 fatty acids, folic acid, and coenzyme Q10.

A recent meta-analysis in the Journal of the American College of Cardiology showed that omega-3 supplementation decreased cardiovascular mortality risk by 7%, heart attack risk by 15%, and coronary heart disease risk by 14%, Jacobson pointed out.

Folic acid and coenzyme Q10 also had a noteworthy impact, with folic acid supplementation decreasing stroke risk by 16%, and coenzyme Q10 supplementation decreasing all-cause death by 32%. 

Whatever pill or tablet you choose, just remember that supplements are just one piece of the heart health puzzle. Diet, exercise, sleep, stress levels, and genetics all influence the big picture of your cardiovascular well-being.