Multivitamin use and the risk of hypertension in a prospective cohort study of women.

Objective: Despite the widespread use of multivitamin supplements, little is known regarding their effects on blood pressure (BP) and the development of hypertension. We, therefore, sought to prospectively investigate how multivitamin use was associated with incident hypertension among middle-aged and older women.

Methods: We studied 28 157 women from the Women's Health Study aged at least 45 years and free of cardiovascular disease, cancer, and hypertension at baseline. Women reported information on a wide range of lifestyle, clinical, and dietary factors, including multivitamin and other supplement use at baseline. Hypertension was identified on baseline and annual follow-up questionnaires. Incident hypertension was defined as either a new diagnosis of hypertension by a physician, initiation of antihypertensive medication, newly reported SBP at least 140 mmHg, or DBP at least 90 mmHg during follow-up.

Results: During a mean follow-up of 11.5 years, we identified 16 316 cases of incident hypertension. We found that neither baseline (hazard ratio = 1.03, 95% confidence interval: 1.00, 1.07) nor time-varying multivitamin use (hazard ratio = 0.97, 95% confidence interval: 0.94-1.00) were associated with the risk of incident hypertension in multivariable-adjusted models. When we investigated the duration of multivitamin use reported at baseline, we also observed no association with the risk of hypertension.

Conclusion: The results from this prospective study of middle-aged and older women suggest that neither baseline multivitamin use nor time-varying multivitamin use is associated with the risk of developing hypertension.