Substrate utilization and work efficiency during submaximal exercise in vitamin C depleted-repleted adults

Int J Vitam Nutr Res. 1999 Jan;69(1):41-4. doi: 10.1024/0300-9831.69.1.41.


A placebo-controlled, depletion-repletion protocol was utilized to examine the effect of vitamin C status on substrate utilization during a 90 min walk at 50% maximal oxygen consumption (VO2max). Nine vitamin C depleted subjects (plasma vitamin C < 28 mumol/L) agreed to participate in the 5-week study (aged, 27.6 +/- 2.5 years, mean +/- SE; 5 females, 4 males). Subjects were apparently healthy but unaware of their vitamin C status. Prior to the experimental period, VO2max was measured using open-circuit spirometry during a graded walking protocol. Subjects ingested a placebo capsule daily during weeks 1-3 and a 500 mg vitamin C capsule daily during weeks 4-5 of the experimental study. Mean plasma vitamin C rose nearly 3-fold and mean plasma carnitine fell by nearly 20% at repletion (week 5) versus depletion (week 3). At the end of weeks 3 and 5, subjects completed a 90 minute treadmill walk at an exercise intensity of 50% VO2max. The relative contribution of fat utilized for energy during walking did not differ in the vitamin C depleted versus repleted states. However, work performed by subjects and gross efficiency during exercise increased significantly at repletion versus depletion (10% and 15%, respectively). These data indicate that vitamin C depletion is associated with reduced work efficiency during submaximal exercise.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Ascorbic Acid / administration & dosage*
  • Ascorbic Acid / blood
  • Ascorbic Acid Deficiency / metabolism*
  • Energy Metabolism*
  • Exercise / physiology*
  • Female
  • Humans
  • Lipid Metabolism
  • Male
  • Nutritional Status
  • Oxygen Consumption
  • Placebos


  • Placebos
  • Ascorbic Acid