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NEW ORLEANS — A sample of popular over-the-counter supplements had little direct clinical evidence to support their claims, despite citing clinical trials and other research, an evaluative study found.

Two of the eight heavily advertised supplements examined — Relief Factor and Nugenix’s Total-T and Free T products — had no clinical research of any kind available, reported Michael Steinberg, PharmD, of the Massachusetts College of Pharmacy and Health Sciences in Worcester.

And none had independent, patient-oriented clinical outcome data that strongly supported their claims, according to a presentation at the American Society of Health-System Pharmacists midyear meeting here.

“I could not find a single one with independent clinical research, with what we would consider legitimate [evidence on] how the product was actually doing something positive,” Steinberg told MedPage Today.

The U.S. dietary supplement industry, according to some estimates, was valued at over $53 billion in 2023. However, under current federal law and FDA regulations, supplements do not undergo the same level of testing required for prescription products. The burden of proof largely falls on consumers to evaluate the often murky health claims made in supplement packaging and advertising.

Pieter Cohen, MD, of Cambridge Health Alliance and Harvard Medical School in Boston, who was not involved in the study but has conducted research on dietary supplements, emphasized in an email to MedPage Today that companies selling supplements are not required to back their health claims up with evidence from clinical trials.

“In fact, supplement companies could claim health benefits for their products even if the product has never been tested, even in animal studies,” he noted. “This poster is a good reminder that clinicians should not assume that health claims on supplement labels have any clinical evidence in humans to support them.”

Steinberg used a convenience sample of eight products that are advertised commonly on television or radio and contain a variety of ingredients ranging from herbal products to vitamins and amino acids. He conducted a literature search of the products’ commercial names in Medline and Google to identify associated clinical trials that included human subjects, along with reviewing product websites for any additional clinical evidence.

These products and what they claimed to improve were:

• Prevagen, marketed for mild memory loss
• Kidney COP (calcium oxalate protector), to reduce calcium oxalate crystal growth
• Crystal Flush, for athlete’s foot, ring worm, and toenail health
• Super Beets, for blood pressure, energy, heart health, and circulation
• Nutrafol products (including Nutrafol Postpartum, Nutrafol Men, and others), for hair growth
• Nugenix Total-T and Free T, marketed for muscle mass, adenosine triphosphate, cellular energy production, exercise performance, libido, lean muscle mass, strength, endurance, and body composition
• SeroVital and SeroVital Advanced, to improve sleep, energy, muscle mass, mood, lines and wrinkles, skin, and weight
• Relief Factor, marketed for inflammation, pain, biological stress, and genetic expression of enzymes

While multiple potential benefits are hinted at in commercials, patients often don’t know if there’s any evidence to support those claims, Steinberg said. “For most of the products, there are actually no clinical trials that actually support their use,” he said.

No clinical research turned up for Nugenix and Relief Factor, while Kidney COP and Crystal Flush products relied on evidence from articles published on the activity of individual agents in the product, rather than data on the products themselves with their particular combination of ingredients.

Two others, Super Beets and SeroVital, had pharmacokinetic and pharmacodynamic studies that did not evaluate outcomes of clinical significance. Only two — Prevagen and Nutrafol — had randomized controlled trials associated with their product.

The Nutrafol study did find a statistically significant increase in measured terminus and vellus hairs for a small target area of the scalp versus placebo. However, other improvements were in subjective measures like hair growth and hair quality. The 6-month trial included 40 women under age 65 with self-perceived hair thinning. A single-arm trial in a diverse group of 98 men and women reported improved investigator ratings for baseline hair growth, coverage, density, and volume with the supplement. Nutrafol also published another placebo-controlled trial that found similar results in a slightly older group of women, although not mentioned in the presentation.

Prevagen’s study found statistically significant benefits in some performance measures and in one patient subgroup for the main outcome of International Shopping List Test, a standardized assessment of verbal list learning and memory. However, no statistically significant differences were found between the placebo and Prevagen groups overall. The Federal Trade Commission and the New York State Attorney General even charged the supplement maker with false advertising connected to their study in 2017.

Limitations included a small sample of products analyzed, and the convenience sampling design. The study did not provide findings on frequency or content of advertising for these products compared to others, cost of the supplements, supplement sales, or safety of supplements or supplement ingredients.