Does supplemental vitamin C increase cardiovascular disease risk in women with diabetes?

Am J Clin Nutr. 2004 Nov;80(5):1194-200. doi: 10.1093/ajcn/80.5.1194.


Background: Vitamin C acts as a potent antioxidant; however, it can also be a prooxidant and glycate protein under certain circumstances in vitro. These observations led us to hypothesize that a high intake of vitamin C in diabetic persons might promote atherosclerosis.

Objective: The objective was to examine the relation between vitamin C intake and mortality from cardiovascular disease.

Design: We studied the relation between vitamin C intake and mortality from total cardiovascular disease (n = 281), coronary artery disease (n = 175), and stroke (n = 57) in 1923 postmenopausal women who reported being diabetic at baseline. Diet was assessed with a food-frequency questionnaire at baseline, and subjects initially free of coronary artery disease were prospectively followed for 15 y.

Results: After adjustment for cardiovascular disease risk factors, type of diabetes medication used, duration of diabetes, and intakes of folate, vitamin E, and beta-carotene, the adjusted relative risks of total cardiovascular disease mortality were 1.0, 0.97, 1.11, 1.47, and 1.84 (P for trend < 0.01) across quintiles of total vitamin C intake from food and supplements. Adjusted relative risks of coronary artery disease were 1.0, 0.81, 0.99, 1.26, and 1.91 (P for trend = 0.01) and of stroke were 1.0, 0.52, 1.23, 2.22, and 2.57 (P for trend < 0.01). When dietary and supplemental vitamin C were analyzed separately, only supplemental vitamin C showed a positive association with mortality endpoints. Vitamin C intake was unrelated to mortality from cardiovascular disease in the nondiabetic subjects at baseline.

Conclusion: A high vitamin C intake from supplements is associated with an increased risk of cardiovascular disease mortality in postmenopausal women with diabetes.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Antioxidants / administration & dosage
  • Antioxidants / adverse effects*
  • Ascorbic Acid / administration & dosage
  • Ascorbic Acid / adverse effects*
  • Cardiovascular Diseases / chemically induced*
  • Cardiovascular Diseases / epidemiology
  • Cardiovascular Diseases / mortality
  • Diabetes Mellitus
  • Diet Surveys
  • Female
  • Humans
  • Iowa / epidemiology
  • Middle Aged
  • Postmenopause
  • Prospective Studies
  • Registries
  • Surveys and Questionnaires


  • Antioxidants
  • Ascorbic Acid