"It is remarkable to think that treating a person with a sub-optimal dose of vitamin D for a few years would overcome the consequences of a lifetime of vitamin D deficiency that has been associated with increased risk for many deadly cancers, cardiovascular disease, neurocognitive dysfunction and autoimmune diseases. These chronic illnesses likely were initiated many years before they become manifest. Most of the meta-analyses reviewed by the authors were studies that were relatively short term and used suboptimal doses of vitamin D.

 

Bottom Line: Meta-Analyses and rehashed meta-analyses, including this one [Allan, 2016], that are promoted in the lay press as new studies, demonstrating that vitamin D has little health benefit beyond musculoskeletal health needs more scrutiny. Vitamin D has existed on this planet for more than 500 million years. Our hunter-gatherer forefathers outside every day were likely making thousands of IUs of vitamin D daily. Maasai herders have blood levels of 25(OH)D of approximately 40-50 ng/mL. To achieve this level an adult would need to ingest at least 2000 IUs of vitamin D daily; and if obese would require 5000 IUs daily. These are the doses of vitamin D that can sustain a blood level of 25(OH)D of at least 30 ng/ml which is thought to be required for the many of the non-musculoskeletal health benefits of vitamin D. This Narrative Review [Allan, 2016] did not consider the scientific literature on the biological functions of vitamin D and only focused on meta-analyses of studies that used suboptimal doses of vitamin D that either did not measure nor achieve a blood level of 25(OH)D of at least 30 ng/ml. Thus it

provides little insight into the non-musculoskeletal health benefits of vitamin D."

Professor of Medicine, Physiology and Biophysics; Director of the General Clinical Research Center; Director of the Vitamin D, Skin and Bone Research Laboratory; 

Director, Biologic Effects of Light Research Center

Boston University Medical Center