Research in the news: D-Aspartic Acid
by Jeff S. Volek, Ph.D., R.D.
Testosterone is a natural hormone secreted by the body that has a major role in promoting muscle growth and overall vitality. Clinically low testosterone may affect as many as one-third of men aged 46 to 89 years. In men, the decline in testosterone usually begins in their late thirties and decreases at a relatively constant rate of 1-3% per year. Declining testosterone and muscle mass is associated with poor performance, depression, lack of sexual interest, erectile dysfunction, poor immune function and low bone density.
The good news is that healthy lifestyle behaviors like weight training can dramatically slow the natural decline in testosterone. Also, don’t eat a low fat diet or reduce calories too much if you’re trying to lose weight as these are linked to lower testosterone levels. Researchers recently tested a supplement that may help too.
Italian researchers examined the effect of D-aspartic acid (DAA), a non-essential amino acid, which plays a role in energy metabolism and testosterone levels in middle-aged men. The men (27 to 37 years old) had normal testosterone levels and were supplemented with 3.12 grams/day of DAA for 12 days. A matched group of men received a placebo. The DAA group showed a gradual increase in testosterone of 16% after 6 days and 42% at 12 days. All but 3 of the 23 subjects showed an increase in testosterone demonstrating the consistency of the effect. Testosterone levels were still elevated after 3 days of DAA cessation.
The researchers also measured luteinizing hormone (LH), a potent stimulator of testosterone secretion in males. The DAA group showed a 33% increase in LH after 12 days. The researchers also performed experiments in animals that confirmed the significant role of DAA in the release of testosterone and LH and shed additional light on the mechanism of action. It was shown that DAA accumulated in the testes as well as the anterior pituitary in the brain where LH is produced. This plays a role in the stimulatory effect of DAA on hormone production.
This single study needs to be replicated, but preliminary evidence suggests that 3 grams/day of DAA may result in a modest testosterone-raising effect.