A potentially harmful stimulant is being added to some dietary supplements under an unfamiliar name, putting the health of some people at risk.
A study published earlier this month concluded that pharmaceutical doses of oxilofrine are in 14 over-the-counter (OTC) brands of dietary supplements.
The dietary supplement labels list the ingredient as methylsynephrine, which is another name for oxilofrine, or some other close variation. The ingredient is also labeled as “extract of Acacia rigidula.”
The study was released a week after officials at the Food and Drug Administration (FDA) sent a letter to seven companies warning them that they are improperly labeling methylsynephrine as a dietary ingredient.
The agency gave the companies 15 business days to respond. The agency warned them that the FDA could remove products from the markets under such circumstances.
The Potential Dangers
Oxilofrine is linked to serious adverse events, including nausea, vomiting, agitation, abnormally high heart rates, chest pain, and cardiac arrest.
Oxilofrine is banned by many sports organizations, including the World Anti-Doping Agency, Major League Baseball, and the National Football League
It was responsible for track sprinters Asafa Powell and Tyson Gay being barred from competition in 2013 even though they said they didn’t know they had consumed the substance.
“Our endeavor is to make sure it is not in there and athletes don’t test positive and the American public doesn’t inadvertently consume large quantities of a product that may be dangerous,” said John Travis, one of the study’s authors and a senior research scientist at NSF International, which tests and certifies dietary supplements.
Olixofrine, a pharmaceutical drug, is not approved for use in the U.S., but has been used to treat low blood pressure in Europe.
“It’s not a legal dietary supplement ingredient,” Travis told Healthline. “It’s a drug.”
The products in the NSF study that were found to contain methylsynephrine include ephedra, Free Shredder, Hypercor, and Miami Lean.
The companies state on their labels that their products burn fat or provide energy or “euphoric weight loss.”
The study authors explained that the FDA banned ephedrine from supplements in 2004 due to serious side effects.
After that, synthetic drugs, such as oxilofrine, were added in order to replace the stimulant effects of ephedra, a plant that contains ephedrine.
Becoming More Common
Travis said he doesn’t know why manufacturers have been including methylsynephrine in their products lately.
He said there could be confusion over the similarity in names of different products.
But, he noted, the drug has been showing up more often lately.
Travis has researched the ingredients of dietary supplements for years and has seen trends like this appear with other rogue ingredients.
Those include DMAA, a stimulant that was previously found in dietary supplements.
Ingestion of DMAA can raise blood pressure and lead to cardiovascular problems, including shortness of breath, tightening in the chest, and even heart attack.
The FDA considers it to be an illegal ingredient in dietary supplements and has worked to remove products containing it from the market.
In the recent study, Travis and his colleagues tested for the presence of oxilofrine in 27 brands of supplements with some variation of the word methylsynephrine listed in the ingredients.
They found that it was contained in 14 of them at doses ranging from 0.0003 to 75 mg per serving.
Oxilofrine has been used at doses of 16 mg to 40 mg in Germany, where it was developed as a pharmaceutical drug to treat low blood pressure.
Following instructions for some of the dietary supplements, consumers could ingest up to 250 mg of oxilofrine daily.
The study’s authors say that the effects of inadvertently consuming that much are unknown. Studies on lower doses suggest effects such as heart palpitations, arrhythmias, and increased blood pressure.
“Adolescents who use these products might be placing themselves at risk of serious harm,” said Dr. Pieter Cohen, one of the study’s authors and an assistant professor of medicine at Harvard Medical School. “The larger-than-adult doses we found might overstimulate their smaller, growing bodies.”
He noted that in countries where doctors prescribe oxilofrine, the usual dose for the drug for adolescents is 24 mg or less.
“Combined with physical activity and other stimulants commonly found in supplements, the consequences could be catastrophic,” he said.
No ‘Magic Bullets’
Daniel Fabricant, Ph.D., executive director and chief executive officer of the Natural Products Association, noted that the FDA made two key points in its letters to supplement makers.
The agency said methylsynephrine is not found in nature and therefore not eligible to be contained in dietary supplements.
Even if it was eligible to be a dietary ingredient, he added, the companies would need to notify the FDA about a new ingredient and provide safety data.
The membership of his organization includes dietary supplement makers, although not the ones that received the warning letters.
Fabricant has firsthand knowledge of the FDA, having served as director of dietary supplement programs at the agency.
He noted that dietary supplements are generally pretty safe, but customers should be savvy.
“Legitimate players don’t sell magic bullets,” he said.