Vitamin D insufficiency in pregnant women may be associated with several adverse effects for the mother and newborn. Randomized clinical trials are currently investigating whether vitamin D supplementation can limit cognitive deterioration and disease progression in subjects with neurodegenerative disease. It is not yet known whether correcting vitamin D deficiency in individuals with glucose intolerance can decrease the risk of progression to type 2 diabetes mellitus. (More information)Ĭurrent evidence from observational studies suggests an inverse relationship between circulating vitamin D concentrations and risk of type 2 diabetes mellitus. Various observational studies have reported inverse associations between vitamin D status and the susceptibility or severity of autoimmune diseases, including type 1 diabetes mellitus, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus. Randomized controlled trials are needed to evaluate whether cancer prevention may benefit from vitamin D supplementation. Observational studies have reported associations between low sun exposure, poor vitamin D status, and increased risk of developing colorectal and breast cancer. Vitamin D can regulate cell differentiation and growth by binding to the vitamin D receptor found in most body cells. Randomized clinical trials indicate that supplementation with at least 800 IU/day of vitamin D may reduce the risk of falls and fractures in older individuals. Secondary hyperparathyroidism due to vitamin D insufficiency can increase bone breakdown and precipitate osteoporosis. Severe vitamin D deficiency causes rickets in children and osteomalacia in adults.
Vitamin D is important for normal bone development and maintenance. Vitamin D also exhibits many non-skeletal effects, particularly on the immune, endocrine, and cardiovascular systems. Vitamin D is essential for maintenance of bone mineralization through the regulation of calcium and phosphorus homeostasis. Through binding to the vitamin D receptor (VDR), 1α,25-dihydroxyvitamin D can regulate the expression of hundreds of genes involved in skeletal and other biological functions. Vitamin D can be synthesized in the skin upon exposure to sunlight and is then metabolized in the liver and kidney to the metabolically active form called 1α,25-dihydroxyvitamin D.
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