Antioxidant vitamins intake and the risk of coronary heart disease: meta-analysis of cohort studies

  1. Zheng Yea⇓
  2. Honglin Songb
  1. a Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK
  2. b Department of Oncology, Strangeways Research Laboratory, University of Cambridge, Cambridge, UK
  1. Correspondence to Dr Zheng Ye, PhD, Department of Public Health and Primary Care, University of Cambridge, Strangeways Site, Cambridge CB1 8RN, UK Tel: +44 01223 741530; fax: +4401223 741339; e-mail: zy215@medschl.cam.ac.uk

Abstract

Background Many epidemiological studies have reported that antioxidant vitamin intake from diet or supplements are associated with a lower risk of coronary heart disease (CH D), the findings are, however, inconsistent. We undertook a meta-analysis of cohort studies to examine the relations between antioxidant vitamins (vitamins C, E, and β-carotene) and CHD risk.

Methods and results We included all the relevant cohort studies if they provided a relative risk and corresponding 95% confidence interval (CI) of CHD in relation to antioxidant vitamins intake from diet or supplement. Fifteen cohort studies were identified involving a total of 7415 incident CHD cases and 374488 participants with a median follow-up of approximately 10, 8.5, and 15 years for vitamins C, E, and β-carotene, respectively. Pooled estimates across studies were obtained by random-effects model. The potential sources of heterogeneity and publication bias were also estimated. For vitamins C, E, and β-carotene, a comparison of individuals in the top third with those in the bottom third of baseline value yielded a combined relative risk of 0.84 (95% CI, 0.73-0.95), 0.76 (95% CI, 0.63-0.89), and 0.78 (95% CI, 0.53-1.04), respectively. Subgroup analyses show that dietary intake of vitamins C and E and supplement use of vitamin E have an inverse association with CHD risk, but supplement use of vitamin C has no significant association with CHD risk. In the dose-response meta-analysis, each 30 mg/day increase in vitamin C, 30IU/day increase in vitamin E, and 1 mg/day increase in β-carotene yielded the estimated overall relative risk for CHD of 1.01 (95% CI, 0.99-1.02), 0.96 (95% CI, 0.94-0.99), and 1.00 (95% CI, 0.88-1.14), respectively.

Conclusions Our findings in this meta-analysis suggest that an increase in dietary intake of antioxidant vitamins has encouraging prospects for possible CHD prevention.

  • Received December 6, 2006.
  • Accepted August 14, 2007.

 

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