Long-Term Effect of Multivitamin Supplementation on Incident Self-Reported Hypertension and Blood Pressure Changes in the COSMOS Trial

Abstract

Background Multivitamin-multimineral (MVM) supplements have been associated with lower blood pressure (BP) in several small trials. We investigated the effects of a MVM on incident hypertension and BP in a secondary analysis of the COcoa Supplement and Multivitamin Outcomes Study (COSMOS). Methods COSMOS is a 2×2 factorial, double-blinded RCT testing effects of cocoa extract and MVM supplementation among women aged ≥65 years and men aged ≥60 years. Among 8905 COSMOS participants free from hypertension, effects of MVM supplementation on incident hypertension were investigated. Hypertension diagnosis was ascertained through self-reports. Additionally, in two substudies with BP measurements (N = 529 at clinic by research staff and 994 at home by technician), we evaluated the effects on 2-year BP changes. Results Incident hypertension was observed in N = 1034 (22.9%) in MVM arm and N = 1039 (23.6%) in placebo arm over a median of 3.4 years (IQR: 3.0, 3.9) of follow-up, with hazard ratio (HR) 0.98 [95% CI: 0.90, 1.06]. Effects differed according to baseline diet quality, with HRs of incident hypertension 0.81 [0.70, 0.95] and 1.14 [1.01, 1.28] among participants with lower and higher Alternate Mediterranean Diet score, respectively (P-interaction =. 001). There was no effect of MVM on 2-year changes in systolic BP (4.4 mmHg in MVM; 4.5 mmHg in placebo), while pronounced effects were observed for baseline normal BP (P-interaction =. 004). Conclusions MVM supplementation versus placebo did not reduce hypertension incidence or lower BP overall. Exploratory analyses showed greater reduction in hypertension risk and BP changes among those with lower dietary quality and normal BP at baseline, respectively. Clinical Trial Registration NCT02422745.