In pooled analyses, multivitamin use was significantly associated with a lower incidence of any cancer (odds ratio [OR], 0.93 [95% CI, 0.87-0.99]…However, the evidence for multivitamins had important limitations
Limited evidence suggested some supplements may be associated with higher risk of serious harms (hip fracture [vitamin A], hemorrhagic stroke [vitamin E], and kidney stones [vitamin C, calcium])
Vitamin and mineral supplementation was associated with little or no benefit in preventing cancer, cardiovascular disease, and death, with the exception of a small benefit for cancer incidence with multivitamin use.
Beta-carotene: supplementation associated with increased risk of lung cancer and cardiovascular mortality.
Vitamins D and E: not associated with increased or decreased risk of all-cause mortality, cardiovascular disease or cancer. In summary, no benefit.
Based on these findings, the United States Preventive Services Taskforce 1) recommends against the use of beta-carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer and 2) states that there’s insufficient evidence to assess the benefits or harms of multivitamins or other single or paired nutrient supplements for the prevention of cardiovascular disease or cancer.
My take: Most people will not benefit from vitamin supplements and should focus on developing a healthy diet. Certain populations, including pregnant women and those with intestinal disorders, do need additional vitamins.
