Male supplement components lack evidence on efficacy

Many over-the-counter male supplements claim to help improve testosterone or ease erectile dysfunction (ED), but peer-reviewed trial evidence remain sparse, a recent systematic review has found.

Looking through the biggest online retailers, the researchers identified the 16 of the most popular male testosterone and ED supplements in the US. From these, 37 ingredients (16 from testosterone and 21 from ED supplements) were identified. PubMed was searched for randomized controlled trials (RCTs) investigating their efficacies.

Among the testosterone supplements, the most commonly used ingredients were aspartate, fenugreek, L-arginine, zinc, Tribulus, and Eurycoma longifolia. PubMed returned 59 trials that provided evidence regarding these ingredients.

The most-studied components were zinc, fenugreek, and Tribulus; of the 16 identified ingredients in testosterone supplements, six had no published evidence at all. There were also no available data for whole supplement products.

Overall, 69 percent of the ingredients in testosterone supplements had published peer-reviewed evidence of their efficacy. Nevertheless, only 13 percent (n=2; E. longifola and Tribulus) had strong positive findings in support of their use, while in 81 percent, evidence was either indeterminate or completely lacking or negative.

On the other hand, ED supplements most commonly contained ingredients like the horny goat weed, yohimbine, Tribulus, E. longifolia, and L-arginine. Notably, almost half (48 percent) of the identified ingredients had no published data, as did whole supplement products. Overall, 52 percent of ingredients had available peer-reviewed data.

Twenty-four percent of the identified ED supplement ingredients were supported by strong positive evidence, while 57 percent had either indeterminate or completely lacking or negative evidence.