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A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance – Part 28
  1. K Currell1,
  2. D R Moore2,
  3. P Peeling3,
  4. L M Burke4,
  5. S J Stear5,
  6. L M Castell6
  1. 1Department of Performance Nutrition, English Institute of Sport, Loughborough, UK
  2. 2Department of Nutrition & Health, Nestle Research Centre, Lausanne, Switzerland
  3. 3School of Sport Science, The University of Western Australia, Crawley, Australia
  4. 4Australian Institute of Sport, Canberra, Australia
  5. 5Performance Influencers Ltd, London, UK
  6. 6Green 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 28 includes a supplement purported to combat fatigue and enhance growth hormone (ornithine); a well-known ingredient (phenylalanine) of a well-known sweetener (aspartame); a possible energy enhancer via 2,3 diphosphoglycerate (phosphate); and a rather dubious supplement purported in the early 1940s to have a wide range of medicinal effects (pangamic acid). Of these, only phosphate appears to have some credible evidence to support the claims of an ergogenic effect.


K Currell

Ornithine is an amino acid which plays a key role in the urea cycle, facilitating the disposal of ammonia. Ammonia is produced during intense exercise and may be one of the causes of fatigue. There is some evidence that L-ornithine hydrochloride supplementation prior to high-intensity exercise may prevent fatigue and improve performance by modulating the metabolism of ammonia.1 At present, the evidence is far from conclusive with a need to conduct more research using valid measures of performance.

It has been suggested that ornithine supplementation will promote the secretion of growth hormone within humans.2 However, research has not been conducted to show whether this may enhance the adaptation to training and ultimately lead to an improvement in the performance.

One potential avenue of future research is ornithine-α-ketoglutarate. This has been shown to improve the recovery of individuals from burns, trauma and in the postoperative state. It may also be a precursor of nitric oxide.2 At present, there is not enough evidence to support the use of ornithine in sport performance. However, further research should be conducted to investigate its use.


DR Moore

Phenylalanine is …

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  • Competing interests None.

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