Food supplements touted to boost levels of testosterone are among the most sought after supplements by bodybuilders and athletes, and those just seeking added muscle gains. This is particularly true for people who refuse to use pharmaceutical sources of testosterone, such as testosterone itself, or anabolic steroid drugs, which are structurally manipulated forms of testosterone and its byproduct, dihydrotestosterone (DHT). Testosterone is one of the most anabolic hormones in the body, and the use of large doses of testosterone or anabolic steroids are largely responsible for the massive bodies displayed by professional bodybuilders and athletes. Bodybuilders use other anabolic drugs besides anabolic steroids, such as growth hormone, but testosterone and anabolic steroids are by far the most anabolic drugs used today. The other drugs only work when used in conjunction with high dose steroid regimes. In order to satisfy market demand, supplement purveyors are always on the lookout for natural substances that may boost testosterone levels. This is especially true now that the Designer Steroid Act of 2014 has recently become law. This new law effectively bans all chemical and synthetic possible testosterone boosters, including those that are actually thinly disguised anabolic steroids themselves. This leaves a choice of mainly herbal sources of testosterone boosters, DHEA, and D-aspartic acid, an amino acid analogue.
I covered herbal sources of putative testosterone boosters in the April issue of Applied Metabolics, along with a brief overview of D-aspartic acid (DAA). Although it isn't an herbal substance, I included DAA in that article because DAA is a popular supplement thought to be an effective testosterone booster. But as I pointed out in the article, the research that proves the efficacy of DAA is derived mainly from studies of isolated cells of animals, along with two positive human studies. One of these studies is what really set the DAA marketing train in motion, since it showed a 42% boost in testosterone levels in the men who ingested 3 grams a day of DAA. Although advertisements in magazines for DAA still often tout the results of this study, what they fail to mention is that the study involved sedentary men who didn't exercise, and were being treated for infertility. In short, these men started with a low testosterone level. In contrast, most men who regularly engage in resistance exercise show higher basal or resting levels of both total and free or active testosterone. Clearly, what was missing was a study that examined the effects of DAA in young men engaged in resistance exercise. That deficit was cleared with the publication of a study that involved young men (average age, 22) who were habitually engaged in resistance exercise. The men continued their regular exercise programs, with some of them ingesting a placebo, while others ingested the suggested dose of 3 grams a day of DAA. The study lasted for 28 days, with the results showing no changes in the . . .