Three Weeks of Creatine Monohydrate Supplementation Affects Dihydrotestosterone to Testosterone Ratio in College-Aged Rugby Players

Clin J Sport Med. 2009 Sep;19(5):399-404. doi: 10.1097/JSM.0b013e3181b8b52f.

Abstract

Objective: This study investigated resting concentrations of selected androgens after 3 weeks of creatine supplementation in male rugby players. It was hypothesized that the ratio of dihydrotestosterone (DHT, a biologically more active androgen) to testosterone (T) would change with creatine supplementation.

Design: Double-blind placebo-controlled crossover study with a 6-week washout period.

Setting: Rugby Institute in South Africa.

Participants: College-aged rugby players (n = 20) volunteered for the study, which took place during the competitive season.

Interventions: Subjects loaded with creatine (25 g/day creatine with 25 g/day glucose) or placebo (50 g/day glucose) for 7 days followed by 14 days of maintenance (5 g/day creatine with 25 g/day glucose or 30 g/day glucose placebo).

Main outcome measures: Serum T and DHT were measured and ratio calculated at baseline and after 7 days and 21 days of creatine supplementation (or placebo). Body composition measurements were taken at each time point.

Results: After 7 days of creatine loading, or a further 14 days of creatine maintenance dose, serum T levels did not change. However, levels of DHT increased by 56% after 7 days of creatine loading and remained 40% above baseline after 14 days maintenance (P < 0.001). The ratio of DHT:T also increased by 36% after 7 days creatine supplementation and remained elevated by 22% after the maintenance dose (P < 0.01).

Conclusions: Creatine supplementation may, in part, act through an increased rate of conversion of T to DHT. Further investigation is warranted as a result of the high frequency of individuals using creatine supplementation and the long-term safety of alterations in circulating androgen composition. STATEMENT OF CLINICAL RELEVANCE: Although creatine is a widely used ergogenic aid, the mechanisms of action are incompletely understood, particularly in relation to dihydrotestosterone, and therefore the long-term clinical safety cannot be guaranteed.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Anthropometry
  • Creatine / pharmacology*
  • Cross-Over Studies
  • Dietary Supplements
  • Dihydrotestosterone / blood*
  • Double-Blind Method
  • Football
  • Humans
  • Male
  • Testosterone / blood*
  • Young Adult

Substances

  • Dihydrotestosterone
  • Testosterone
  • Creatine