Effects of dietary nitrate supplementation on the oxygen cost of exercise and walking performance in individuals with type 2 diabetes: a randomized, double-blind, placebo-controlled crossover trial

Anthony I. Shepherd, Mark Gilchrist, Paul G. Winyard, Andrew M. Jones, Ewelina Hallmann, Renata Kazimierczak, Ewa Rembialkowska, Nigel Benjamin, Angela C. Shore, Daryl P. Wilkerson

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Abstract

Dietary nitrate supplementation has been shown to reduce the oxygen (O2) cost of exercise and enhance exercise tolerance in healthy individuals. This study assessed whether similar effects could be observed in individuals with type 2 diabetes (T2DM). In a randomized, double-blind, placebo-controlled crossover study, 48 participants with T2DM supplemented their diet for 4 days with either nitrate-rich beetroot juice (70 ml/day, 6.43 mmol nitrate/day) or nitrate-depleted beetroot juice as placebo (70 ml/day, 0.07 mmol nitrate/day). After each intervention period, resting plasma nitrate and nitrite concentrations were measured subsequent to participants completing moderate-paced walking. Pulmonary gas exchange was measured to assess the O2 cost of walking. After a rest period, participants performed the 6-min walk test (6MWT). Relative to placebo, beetroot juice resulted in a significant increase in plasma nitrate (placebo, 57±66 vs beetroot, 319±110 µM; P < 0.001) and plasma nitrite concentration (placebo, 680±256 vs beetroot, 1065±607 nM; P < 0.001). There were no differences between placebo juice and beetroot juice for the O2 cost of walking (946±221 vs 939±223 ml/min, respectively; P = 0.59) and distance covered in the 6MWT (550±83 vs 554±90 m, respectively; P = 0.17). Nitrate supplementation did not affect the O2 cost of moderate-paced walking or improve performance in the 6MWT. These findings indicate that dietary nitrate supplementation does not modulate the response to exercise in individuals with T2DM.
Original languageEnglish
Pages (from-to)200-208
Number of pages9
JournalFree Radical Biology and Medicine
Volume86
Early online date18 May 2015
DOIs
Publication statusPublished - 1 Sep 2015

Keywords

  • Type 2 diabetes
  • Nitrate
  • Nitric oxide
  • Exercise
  • Blood pressure
  • Free radicals

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