Since 2000, there has been an increase in research on possible health benefits of vitamin D. However, a 2011 Institute of Medicine (IOM; now the National Academy of Medicine) report concluded that vitamin D was beneficial for bone health but evidence was insufficient for extraskeletal health.1 Several large-scale trials are ongoing to evaluate the effect of vitamin D supplementation on extraskeletal outcomes.2 The IOM report noted possible harm (eg, hypercalcemia, soft tissue or vascular calcification) for intakes above the tolerable upper limit, which is the highest level of intake likely to pose no risk of adverse effects for most adults.1
Rooney MR, Harnack L, Michos ED, Ogilvie RP, Sempos CT, Lutsey PL. Trends in Use of High-Dose Vitamin D Supplements Exceeding 1000 or 4000 International Units Daily, 1999-2014. JAMA. 2017;317(23):2448–2450. doi:10.1001/jama.2017.4392
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