However, the leading trade association for herbal products has questioned the data, citing “a lack of basic understanding of natural products chemistry”.
Yohimbe bark (Pausinystalia yohimbe) contains the active compound yohimbine, which is said to have sexual stimulant and aphrodisiac effects.
Chromatographic analysis of 18 yohimbe commercial dietary supplement samples showed that only one matched the label claims, according to data from Jianghao Sun and Pei Chen from the US Department of Agriculture’s Agricultural Research Service in Beltsville, MD.
Writing in the Journal of Pharmaceutical and Biomedical Analysis the USDA scientists state that two samples contained more yohimbine than claimed on the label, while the rest contained between 0 and 50% of the label claims.
The analysis, and the subsequent conclusions, was questioned by Michael McGuffin, president of the American Herbal Products Association (AHPA).
McGuffin told NutraIngredients-USA that the researchers appear to take the position that a quantitative label claim for the amount of yohimbe bark in a supplement should be equated to an implied quantitative label claim for the contained yohimbine in the products.
“There is nothing in the Food and Drug Administration's labeling regulations for any food product, including herbal dietary supplements, that requires a product made from plants to contain some specific amount of a known constituent, unless the label also claims to contain that specific amount of the named constituent.”
McGuffin also questioned the calculations assumed that the concentration of yohimbine in the single sample of reference bark is the amount of yohimbine in all yohimbe samples.
“It is established in public literature that there can be a range of from 7 to 115 mg yohimbine per gram of yohimbe bark,” he said.
"There is no doubt that the amount of this alkaloid in the yohimbe plant (as in other constituent/plant relationships) varies from sample to sample. And the authors themselves note, 'Although the quantitation result can confirm the yohimbine content in a sample, there is no way to know how similar a commercial dietary supplement sample is to a raw plant material by quantitation of a single component.' And yet when they apply their test results, they ignore this basic (and accurate) premise.
“This is absolutely unscientific and betrays a lack of basic understanding of natural products chemistry,” said McGuffin
Mark Blumenthal, founder & executive director of the American Botanical Council, described the results as “not really surprising”.
“To me, aside from the quality of the yohimbe raw materials and products, the really significant issue is what is the intended use of yohimbe and are all the commercial products adequately labeled with appropriate precautions?
“One of the primary uses for yohimbe products in the market today – other than perhaps the use for erectile dysfunction, which is consistent with its previous medically-sanctioned use – is for improving athletic performance and workouts – a questionable use in my mind,” said Blumenthal.
“And, all potential yohimbe users should be properly and adequately warned of the potential hypertensive effect of yohimbe, as well as its other numerous adverse side effects and contraindications.”
Source: Journal of Pharmaceutical and Biomedical Analysis
Volume 61, Pages 142-149, doi:10.1016/j.jpba.2011.11.013
“Chromatographic fingerprint analysis of yohimbe bark and related dietary supplements using UHPLC/UV/MS”
Authors: Jianghao Sun, Pei Chen