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A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance–Part 34
  1. D S King1,
  2. R Baskerville2,
  3. Y Hellsten3,
  4. D S Senchina4,
  5. L M Burke5,
  6. S J Stear6,
  7. L M Castell7
  1. 1Department of Kinesiology, Iowa State University, Ames, Iowa, USA
  2. 2Hammersley & Partners Medical Practice, Oxford, UK
  3. 3Department of Exercise and Sport Sciences, University of Copenhagen, Copenhagen, Denmark
  4. 4Biology Department, Drake University, Des Moines, Iowa, USA
  5. 5Australian Institute of Sport, Canberra, Australia
  6. 6Performance Influencers Limited, London, UK
  7. 7Green Templeton College, University of Oxford, Oxford, UK
  1. Correspondence to L M Castell, Green Templeton College, University of Oxford, Oxford OX2 6HG, UK; lindy.castell{at}

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Introductory remarks

Part 34 is dominated by a review of prohormones, or more specifically, testosterone prohormones, which cause concern in sports nutrition related to their direct use or inadvertent intake as contaminants in other supplements. When taken specifically for their alleged effects as testosterone alternatives, they may give rise to health problems while failing to achieve the claimed benefits of enhanced strength and muscle mass. Prohormones are a Prohibited Substance on the World Anti-Doping Agency (WADA) list and, even in minute concentrations (as occurs in contaminated supplements) these products can lead to a positive doping outcome. This part also contains brief summaries of ribose and smilax, two supplements which have not lived up to any claims related to benefits to athletic performance.


D S King, R Baskerville

The term prohormone strictly refers to a post-translational peptide that is cleaved by convertases into a variety of bioactive hormones .In the supplement context, prohormones refer to androgenic precursors which, when ingested, become enzymatically activated to testosterone derivatives. An understanding of the biochemical pathways emphasises the similarity between testosterone and its precursors.

Users see prohormones as a natural means to improve muscle strength, body composition and general well-being with fewer side effects than testosterone or synthetic androgenic steroids and a more practical (capsule) form of intake. The marketing strategy of commercial websites is to promote prohormones as ‘legal alternatives’ to testosterone with similar anabolic effects. Of course, many consumers are unaware that these prohormones are included on the WADA list of prohibited substances as well as being illegal for sale or importation in many countries. Prohormones have another concerning role in sports nutrition as contaminants in other sports supplements which account for a large proportion of inadvertent doping offences.

From cholesterol, pregnenolone is produced which converts to testosterone via dihydroepiandosterone (DHEA). The path via DHEA …

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  • Competing interests None.

  • Provenance and peer review Commissioned; not externally peer reviewed.