Vitamin D testing is commonly performed in adults. Evidence is lacking to support vitamin D screening or supplementation in the general population, regardless of baseline serum 25-hydroxyvitamin D levels. The National Academy of Medicine recommends that individuals 70 years and younger consume 600 IU of vitamin D daily and that individuals older than 70 years consume 800 IU daily. This can be achieved through dietary sources, supplements, or both. Achieving the recommended intake prevents serum 25-hydroxyvitamin D levels from decreasing to less than 12 ng/mL in 97.5% of the general population. Randomized controlled trials of vitamin D supplementation in the general population, including patients with low baseline serum 25-hydroxyvitamin D levels, do not demonstrate reduced all-cause mortality or improvement in cardiovascular health. Some patients with prediabetes may benefit from taking at least 3 years of vitamin D supplementation that exceeds the recommended dietary intake to reduce the risk of progression to type 2 diabetes. Randomized controlled trials of vitamin D supplementation for reducing the risk of falls and fractures, cancer, dementia, respiratory infections, and depression; for symptoms of fatigue, hair loss, and chronic pain; and during pregnancy and menopause do not show consistent benefit, including in patients with low baseline serum 25-hydroxyvitamin D levels.
