Effects of vitamins C and E and β-carotene on the risk of type 2 diabetes in women at high risk of cardiovascular disease

A randomized controlled trial

Yiqing Song, Nancy R. Cook, Christine M. Albert, Martin Van Denburgh, Jo Ann E. Manson

Research output: Contribution to journalArticle

99 Citations (Scopus)

Abstract

Background: Vitamin C, vitamin E, and β-carotene are major antioxidants and as such may protect against the development of type 2 diabetes via reduction of oxidative stress. Objective: The purpose of this study was to investigate the longterm effects of supplementation with vitamin C, vitamin E, and β-carotene for primary prevention of type 2 diabetes. Design: In the Women's Antioxidant Cardiovascular Study, a randomized trial that occurred between 1995 and 2005, 8171 female health professionals aged ≥40 y with either a history of cardiovascular disease (CVD) or ≥3 CVD risk factors were randomly assigned to receive vitamin C (ascorbic acid, 500 mg every day), vitamin E (RRR-α-tocopherol acetate, 600 IU every other day), β-carotene (50 mg every other day), or their respective placebos. Results: During a median follow-up of 9.2 y, a total of 895 incident cases occurred among 6574 women who were free of diabetes at baseline. There was a trend toward a modest reduction in diabetes risk in women assigned to receive vitamin C compared with those assigned to receive placebo [relative risk (RR): 0.89; 95% CI: 0.78, 1.02; P = 0.09], whereas a trend for a slight elevation in diabetes risk was observed for vitamin E treatment (RR: 1.13; 95% CI: 0.99, 1.29; P = 0.07). However, neither of these effects reached statistical significance. No significant effect was observed for β-carotene treatment (RR: 0.97; 95% CI: 0.85, 1.11; P = 0.68). Conclusion: Our randomized trial data showed no significant overall effects of vitamin C, vitamin E, and β-carotene on risk of developing type 2 diabetes in women at high risk of CVD. This trial was registered at clinicaltrials.gov as NCT00000541.

Original languageEnglish (US)
Pages (from-to)429-437
Number of pages9
JournalAmerican Journal of Clinical Nutrition
Volume90
Issue number2
DOIs
StatePublished - Aug 1 2009
Externally publishedYes

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Carotenoids
Vitamin E
Type 2 Diabetes Mellitus
Ascorbic Acid
Cardiovascular Diseases
Randomized Controlled Trials
Antioxidants
Placebos
alpha-Tocopherol
Primary Prevention
Oxidative Stress
Health
Therapeutics

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

Effects of vitamins C and E and β-carotene on the risk of type 2 diabetes in women at high risk of cardiovascular disease : A randomized controlled trial. / Song, Yiqing; Cook, Nancy R.; Albert, Christine M.; Van Denburgh, Martin; Manson, Jo Ann E.

In: American Journal of Clinical Nutrition, Vol. 90, No. 2, 01.08.2009, p. 429-437.

Research output: Contribution to journalArticle

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abstract = "Background: Vitamin C, vitamin E, and β-carotene are major antioxidants and as such may protect against the development of type 2 diabetes via reduction of oxidative stress. Objective: The purpose of this study was to investigate the longterm effects of supplementation with vitamin C, vitamin E, and β-carotene for primary prevention of type 2 diabetes. Design: In the Women's Antioxidant Cardiovascular Study, a randomized trial that occurred between 1995 and 2005, 8171 female health professionals aged ≥40 y with either a history of cardiovascular disease (CVD) or ≥3 CVD risk factors were randomly assigned to receive vitamin C (ascorbic acid, 500 mg every day), vitamin E (RRR-α-tocopherol acetate, 600 IU every other day), β-carotene (50 mg every other day), or their respective placebos. Results: During a median follow-up of 9.2 y, a total of 895 incident cases occurred among 6574 women who were free of diabetes at baseline. There was a trend toward a modest reduction in diabetes risk in women assigned to receive vitamin C compared with those assigned to receive placebo [relative risk (RR): 0.89; 95{\%} CI: 0.78, 1.02; P = 0.09], whereas a trend for a slight elevation in diabetes risk was observed for vitamin E treatment (RR: 1.13; 95{\%} CI: 0.99, 1.29; P = 0.07). However, neither of these effects reached statistical significance. No significant effect was observed for β-carotene treatment (RR: 0.97; 95{\%} CI: 0.85, 1.11; P = 0.68). Conclusion: Our randomized trial data showed no significant overall effects of vitamin C, vitamin E, and β-carotene on risk of developing type 2 diabetes in women at high risk of CVD. This trial was registered at clinicaltrials.gov as NCT00000541.",
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