Vitamin C augments lymphocyte glutathione in subjects with ascorbate deficiency

Am J Clin Nutr. 2003 Jan;77(1):189-95. doi: 10.1093/ajcn/77.1.189.

Abstract

Background: Ascorbate and glutathione play central roles in the defense against free radicals and oxidants that are implicated in chronic diseases.

Objective: The objective was to determine the ability of vitamin C supplements to modulate the concentration of glutathione in human lymphocytes.

Design: The effect of vitamin C supplements was determined in a sequential study with time points before supplementation, after 13 wk of vitamin C supplements (500 or 1000 mg/d), and after 13 wk of matching placebo. The supplementation group was selected on the basis of low plasma ascorbate (<33 mmol/L) and consisted of 48 healthy men and women, smokers and nonsmokers, aged 25-64 y. Ascorbate and glutathione were measured in purified lymphocytes.

Results: At baseline, the mean (+/-SD) concentration of plasma ascorbate was 19.5 +/- 7.2 micro mol/L, 22.5 micro mol/L below the median of normal distribution. The ascorbate concentration in plasma was linearly associated with that in lymphocytes (r = 0.53, P < 0.001). On supplementation with vitamin C, lymphocyte ascorbate increased by 51% (from 16.7 +/- 4.9 to 25.3 +/- 6.9 nmol/mg protein; P < 0.001) and was accompanied by an increase of lymphocyte glutathione by 18% (from 22.5 +/- 4.5 to 26.6 +/- 6.5 nmol/mg protein; P < 0.001). After placebo, the ascorbate and glutathione concentrations fell to near baseline concentrations (17.1 +/- 5.4 and 23.5 +/- 6.4 nmol/mg protein, respectively). No significant interaction was observed for sex and smoking status. Finally, the changes in lymphocyte ascorbate after supplementation were strongly associated with changes in lymphocyte glutathione (r = 0.71, P < 0.001). The association suggests that every 1-mol change in ascorbate is accompanied by a change of approximately 0.5 mol in glutathione.

Conclusion: Vitamin C supplements increase glutathione in human lymphocytes.

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 / therapeutic use*
  • Ascorbic Acid Deficiency / blood
  • Ascorbic Acid Deficiency / drug therapy*
  • Chromatography, High Pressure Liquid
  • Female
  • Glutathione / blood*
  • Humans
  • Lymphocytes / drug effects*
  • Lymphocytes / metabolism
  • Male
  • Middle Aged

Substances

  • Glutathione
  • Ascorbic Acid