A new US study suggests that adequate vitamin D supplementation may increase survival for people with vitamin D deficiency.
An observational study to investigate the association between vitamin D deficiency and cardiovascular morbidity and mortality, as well as the effect of supplementation on survival, measured blood concentrations of vitamin D and incidence of cardiovascular-related diseases, such as hypertension, coronary artery disease, and diabetes. The study included 10,899 people with an average age of 58 years (1). Results showed that 70% of the participants were vitamin D deficient (below 30 ng/ml), which was associated with significantly higher incidence of cardiovascular-related diseases, and a 164% higher risk of all-cause mortality. Vitamin D supplementation, however, was linked with a 61% increase in survival rates.
The researchers concluded that there is a significant association between vitamin D supplementation and improved survival for people suffering deficiency. Additional investigation with long-term prospective studies of various vitamin D dosage levels in both healthy and diseased populations were recommended, so as to firmly establish the role of vitamin D supplementation on overall outcomes and mortality. The findings could have implications for current guidelines, commented the scientists, since supplements providing at least 1,000 International Units (IU) per day may be needed to avoid deficiency. To date, prospective studies evaluating vitamin D supplementation are few and have not shown the benefits consistently. However, the researchers suspect that the lack of benefit in these studies may have resulted from suboptimal levels of vitamin D supplementation. Many previous studies of vitamin D supplementation have used doses of 400 to 800 IU, which might not be adequate to ensure optimal serum levels. More appropriate daily supplement doses were recommended: as high as 1,000 to 2,000 IU per day. The Institute of Medicine has recently increased the recommended daily allowance (RDA) to 600 IU.