Consumers should avoid “natural” weight-loss and sports supplements containing higenamine, a plant-based stimulant that may pose a danger to the heart, the authors of a new study in the journal Clinical Toxicology warn.
In 2017, the World Anti-Doping Agency banned all athletes from taking higenamine-containing supplements (because of concerns it would enable users to take in more oxygen and thus give them a competitive edge), but many products sold over the counter or online in the United States still contain the substance. That’s because supplement manufacturers — thanks to successful congressional lobbying by the dietary supplement industry — do not have to prove their ingredients are either safe or effective before they are marketed for sale.
Nor, as the current study shows, do they need to accurately label how much of a particular ingredient is in their supplements.
“What we’ve learned from the study is that there is often no way for a consumer to know how much higenamine is actually in the product they are taking,” said John Travis, a co-author of the study and a senior research scientist at NSF International, in a press release.
“We’re urging competitive and amateur athletes, as well as general consumers, to think twice before consuming a product that contains higenamine,” he added.
The study underscores the dangers that dietary supplements can pose to consumers. As background information in the study points out, more than 23,000 Americans are treated at hospital emergency departments each year for side effects from taking dietary supplements. Weight-loss and sports supplements — which often contain stimulants — contribute to a major proportion of those visits.
Higenamine is derived from various plants, including Sichuan aconite, a Chinese herb, and the berries of the nandina shrub (also known as “heavenly bamboo”).
Although used in traditional remedies, higenamine’s health risks are currently poorly understood. But like ephedra, a dietary supplement that was taken off the market by the U.S. Food and Drug Administration (FDA) in 2004 because it was found to trigger heart attacks and strokes, higenamine is known to speed up the heart. For that reason, intravenous versions of the stimulant are being studied in clinical trials in China as a potential drug for the treatment of several heart-related ailments, including bradyarrhythmias, or slow heart beats.
Higenamine has never been approved as a drug by the FDA.
For the current study, Travis and his co-authors, which included Dr. Pieter Cohen of Harvard University, analyzed the contents of 24 supplements labeled as containing higenamine or one of its synonyms, norcoclaurine and demethylcoclaurine. All the supplements were available for sale in the U.S.
The researchers found that the amount of higenamine in the 24 supplements ranged from trace levels to 62 milligrams per serving. Five of the products listed a specific amount of the substance on their labels, and none of those five amounts was accurate.
Based on the instructions for use of the supplements on the labels, consumers could be exposed to more than 100 milligrams of higenamine per day, the researchers note.
Risks are unknown
And no one really knows whether the higenamine in supplements is safe. Two studies, both funded by a supplement manufacturer, claim to show that the products do no harm, but that research had significant methodological problems. One of the studies, for example, involved only 16 participants (all young and healthy), and the study’s authors do not say how much higenamine the participants received.
“When it comes to higenamine, we don’t yet know for certain what effect high dosages will have in the human body, but a series of preliminary studies suggest that it might have profound effects on the heart and others organs,” said Cohen in the press release.
As with all dietary supplements, caveat emptor.
FMI: You can read the study in full on the Clinical Toxicology website.