title: Nitrate supplementation and human exercise performance: too much of a good thing?
abstract: OBJECTIVE
  Ergogenic supplements in sport events are widely used by popular and competitive athletes to enhance performance and reduce oxygen cost. Beetroot juice and nitrate salts have been increasingly used for the past 5-6 years. The present review discusses the scientific background, the efficiency and potential adverse effects of excessive nitrate supplementation.
  
  
  RESULTS
  There is clear evidence that nitrate from different food ingredients (such as beetroot juice and other vegetables) is converted into nitrite and possibly into nitric oxide, which may promote vasodilation, angiogenesis and mitochondrial biogenesis. The high affinity of nitric oxide towards different enzyme pathways inhibits excessive mitochondrial respiration and, therefore, tissue oxygen consumption. In addition, L-arginine supplements are proposed to stimulate nitric oxide synthesis in the endothelium. On the basis of these biochemical properties, nitrate supplementation has been suggested to athletes to enhance exercise performance.
  
  
  CONCLUSIONS
  The recent publications in human individuals based on L-arginine, beetroot juice or nitrate supplementation revealed either a minor positive effect or no systematic effect on exercise performance, especially in trained athletes. Of note, the sugar content of whole beetroot juice might induce a slightly more pronounced effect. Although reasonable intake of nitrate salts (up to 1 g/day) has no detrimental effect on kidney function, the risk and benefit of higher nitrate intake needs to be evaluated to define the optimal range of supplementation.
authors.affiliation: aUnité de Recherche en Biométrie et Nutrition Appliquée à l'Exercice, Faculté des Sciences de la Motricité, Université libre de Bruxelles (ULB), Brussels, Belgium bSchool of Physical Education and Sport, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Jacques R
authors.initials: JR
authors.lastname: Poortmans
authors.forename: Bruno
authors.initials: B
authors.lastname: Gualano
authors.forename: Alain
authors.initials: A
authors.lastname: Carpentier
mesh_terms: D001120:Arginine / Q000494:pharmacology; D054874:Athletic Performance; D027461:Beta vulgaris / Q000737:chemistry; D019587:Dietary Supplements; D015444:Exercise; D006801:Humans; D009566:Nitrates / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D009566:Nitrates; D001120:Arginine