D-aspartic Acid Supplementation Effects on Body Composition: A Systematic Review of Randomized Clinical Trials on Trained Males

Context: D-Aspartic acid (DAA) is an amino acid found in the brain and reproductive system. Some investigations have reported beneficial effects of DAA on brain function and reproductive system health by increasing testosterone through the hypothalamic-pituitary-gonadal axis. However, its effect on body composition is unknown. Given testosterone's role in muscle growth, this study aimed to evaluate the effect of DAA supplementation on the body composition of trained males. Evidence Acquisition: PubMed, Scopus, Embase, and Web of Science (until 1 August 2021) were searched for this systematic review. Inclusion criteria assumed as clinical trials assessed the effect of DAA on body composition in trained males. After including articles by keywords, the articles were reviewed for meeting the eligibility criteria. Three independent researchers conducted the search and full-text review. Results: Among 134 articles located during the primary search, five articles (47 interventions and 43 controls) were included in the study based on eligibility criteria. All included clinical trials had a low risk of bias. A review of the relevant literature concludes that different doses of DAA (three grams, six grams, 7.12, and 12 grams) in different intervention periods (two weeks, four weeks, and 12 weeks) have no effects on body composition in trained males. Conclusions: DAA supplementation is a low-level booster of testosterone and has no significant effect on the testosterone level in professional male athletes, and cannot alter the body composition.