Large meta-analysis provides no support for use of vitamin supplementation for CVD prevention
Supplemental Vitamins and Minerals for CVD Prevention and Treatment
Introduction and methods
Supplemental vitamin and mineral use is widespread, while the data on their effect on overall health and longevity is unclear. Moreover, there is no general agreement as to whether it is beneficial to take vitamins and minerals or their combinations for the prevention or treatment of CV disease. Consumption of a good diet as part of a healthy lifestyle is generally recommended. These dietary recommendations are increasingly moving towards more plant-based diets that are relatively rich in vitamins and minerals. These diets liberally provide the requirements, but stay below levels of intake that may be associated with adverse effects.
This study reviewed the evidence for supplement use over the last four years since the publication of the evidence  and guidelines  for supplement use of the US Preventive Services Task Force (USPSTF). A systematic review and meta-analysis was performed on existing systematic reviews, meta-analyses and RCTs published between January 2012 and October 2017, including the studies reviewed by the USPSTF. A total of 179 studies were included in this analysis, 15 of which were published after the USPSTF assessment.
- None of the four most commonly used supplements (multivitamins, vitamin D, calcium and vitamin C) had a significant effect on CV outcomes, nor on all-cause mortality.
- Vitamin D was the most studied nutrient, with 43 RCTs included in this study. 16 trials showed an effect in favor of vitamin D, and 17 in favor or control treatment, and 10 were on the unity line. Overall RR for death was 0.99 (95%CI: 0.95-1.03, P=0.58).
- Folic acid (RR: 0.80, 95%CI: 0.69-0.93, P<0.01) and B-complex vitamins (RR: 0.90, 95%CI: 0.81-1.00, P=0.04) showed a significant reduction of stroke.
- Niacin did not impact CVD significantly, but was associated with an increase of all-cause mortality (RR: 1.10, 95%CI: 1.00-1.20, P=0.05)
- Antioxidant mixtures had no effect on CVD outcomes, but showed a significant increase of all-cause mortality (RR: 1.06, 95%CI: 1.00-1.12, P-0.05).
- Vitamins A, B6 and E, beta-carotene, zinc, iron, magnesium, selenium and multivitamins did no show a significant effect on CVD outcomes and all-cause mortality.
This analysis showed no consistent benefit of popular supplements (multivitamins, vitamin D, calcium and vitamin C) for the prevention of CVD, myocardial infarction or stroke, or on all-cause mortality. Thus, these data do not support their continued use. Folic acid alone and B-vitamins with folic acid, B6 and B12 showed an association with a reduction of stroke. Niacin and antioxidants, on the other hand, were associated with an increased risk of all-cause mortality.