Study: Yohimbine extract in health supplements could trigger serious side effects

A consumer looks at dietary supplements sold at the exchange on Ramstein Air Base, Germany, on Sept. 21, 2015. Some dietary supplements sold by the Army and Air Force Exchange Service contain yohimbine. The plant extract is the focus of a new study that found numerous dietary supplements may contain potent levels of yohimbine, which can cause side effects such as hypertension, panic attacks and headaches.


By JENNIFER H. SVAN | STARS AND STRIPES Published: September 23, 2015

KAISERSLAUTERN, Germany — A new study has found that dozens of dietary supplements, including some sold on U.S. military bases, are often mislabeled or lack information about the amounts they contain of a plant extract that can trigger serious side effects.

The extract, known as yohimbine (pronounced “yo-him-BEAN” ), is the most active chemical found in the bark of yohimbe, a small evergreen tree found in Africa, where it’s been used for hundreds of years as a general aphrodisiac and treatment for impotency. The herb can act like a stimulant, raising heart rate and blood pressure. In the United States, it’s found in more than 550 dietary supplements.

For the study, published Tuesday in the Journal of Drug Testing and Analysis, researchers analyzed 49 brands of supplements whose labels say they contain yohimbine or yohimbe, said Pieter Cohen, a doctor and assistant professor at Harvard Medical School, who co-authored the report. Among the brands tested — none of which were named — were those sold by supplement giant GNC, whose products are sold on many military bases.

At the exchange on Ramstein Air Base, yohimbe or yohimbine was listed as an ingredient in at least a half dozen supplements for weight loss and athletic performance enhancement.

Only two of the 49 supplements tested provided accurate information about the quantity of yohimbine they contained as well as other information about the herb’s known adverse effects, according to the study.

Many of the supplements were found to contain much more yohimbine than labeled, often the equivalent of prescription-strength dosages.

One of the products, for example, contained 12.1 mg per recommended serving, which is up to 21 percent greater than the highest strength of prescription yohimbine formerly available, the study says. Most of the products’ labels did not list the quantity of yohimbine. Of the 11 brands that did, many were inaccurately labeled, with actual content of yohimbine ranging from 23 percent to 147 percent of what was on the label.

“What we found … is that it’s impossible from these supplement labels to determine what you are actually getting,” Cohen said in an email.

Cohen and his co-authors attribute this to the lax framework within which supplements are regulated in the United States, where the quantity of an individual component of a plant is not required to be listed on a supplement label. There’s also no requirement that dietary supplements disclose known adverse effects (with the exception of iron).

“This is a particularly concerning finding given that many countries have already banned yohimbine from all over-the-counter products due to its potential serious health effects,” Cohen and his co-authors wrote in the study. Yohimbine supplements are banned in Canada, Australia, the Netherlands and the United Kingdom, they said.

Reported side effects include hypertension, anxiety, rapid heart rate, abdominal pain, hallucinations, incoordination, confusion, chills, lethargy, lupuslike syndrome and renal failure, according to a 2010 study in The Annals of Pharmacotherapy.

Cohen said there is “zero evidence that I know of that yohimbine improves physical performance. Unfortunately, many of our troops are being duped into purchasing this chemical as if it will improve their athletic performance or help them lose weight. Instead of improving their fitness, they might experience side effects such as hypertension, headaches and panic attacks.”

AAFES officials said Tuesday that they were not aware of Cohen’s study.

“As with all supplements, the exchange strives to carry items that are in high demand based on their sales in major supplement retailers such as GNC and Vitamin Shoppe and readily available for customers to purchase online,” said AAFES spokesman Chris Ward in an email.

Ward said the Food and Drug Administration regulates “this category of merchandise” under the Dietary Supplement Health Education Act. “Sale of these products is legal and considered safe when used as directed,” he said.

“If the FDA were to publish adverse effects on or recalls (to) this particular ingredient, we would take immediate action and react according to our established protocol,” he said.

FDA regulates dietary supplements less stringently than conventional foods and drug products. Manufacturers aren’t allowed to advertise misleading or false information, but FDA approval isn’t needed before a product goes on the market.

The military services and their exchange stores have struggled in the past to keep up with the variety of potentially dangerous substances found in supplements, hugely popular with health-conscious troops for body building and weight loss.

Cohen was involved in a study last year that found at least a dozen fitness supplements on the market contained DMBA, a potentially dangerous and untested stimulant that produced effects similar to DMAA, which has been linked to soldier deaths. Exchange stores have since pulled supplements containing both of those stimulants.

Maj. Chris Berman, a pharmacist at Landstuhl Regional Medical Center, said in an email that yohimbine has been given orally to treat erectile dysfunction and for its 'alleged aphrodisiac properties,’ but there’s no convincing evidence that it’s effective.”

The FDA removed yohimbine from prescription status in mid-90s because of its potential for harm, he said. But it was never banned in the United States, and “it has found its way back onto the market in herbal supplements and dietary aides,” Berman said.

Cohen said he’s not aware of any studies that show yohimbine actually improves athletic performance or speeds up weight loss. Perhaps it’s added to dietary supplements “so that a consumer feels a rush, tingling or other sensation when they take the supplement,” causing them to think it must be working, he suggested.

He would like to see products with yohimbine pulled from U.S. and exchange store shelves.

Berman says consumers taking these products should seek medical advice.

“My suggestion to individuals who are taking supplements or dietary aides is to read what they contain and to speak with their health care providers about them, especially if they are taking medications,” he said.


This dietary supplement, advertised as a "preworkout amplifier" and sold in the exchange store on Ramstein Air Base, Germany, is labeled as containing "yohimbe bark powder." A new study has found that dozens of dietary supplements sold over the counter in the United States may contain potentially unsafe levels of yohimbine, derived from a plant extract that can trigger panic attacks, hypertension and other serious side effects.