Some proposed health benefits
bone health (decreased bone fractures)
Challenges with Vitamin D
The lab tests used to measure vitamin D are not standardized and currently are somewhat imprecise. This makes it difficult to determine a threshold for recommending supplementation. Based on a review of multiple studies, the Institute of Medicine recommends keeping a the vitamin D level between 20 and 40 ng/mL. Other organizations recommend keeping the level over 30, and this is what I recommend for my patients.
Benefits of Vitamin D
There is good research supporting the claim that vitamin D helps prevent bone loss and bone fractures in older individuals (over age 65).
Lack of Benefit with Vitamin D
A study released this month (11/10/18) showed that taking vitamin D supplements did not reduce the risk of cancer or cardiovascular disease. Published in the prestigious New England Journal of Medicine, this robust study randomized 25,000 patients - half were given vitamin D and half were given a placebo. There were no differences between the groups in incidence of any kind of cancer or in heart attacks or other cardiovascular events. Some news outlets are stating that vitamin D decreased the risk of death from cancer, but this is an overstatement of the statistics.
bone health (decreased bone fractures) - helpful
cancer prevention - not helpful
heart health - not helpful