Vitamin D3, also known as cholecalciferol, is a form of vitamin D that the body manufactures when skin is exposed to UV radiation from the sun. It’s converted from food sources and sunlight into its active form, calcitriol, by the liver and kidneys.
Vitamin D plays a part in regulating cellular growth and keeping the nervous and immune system functioning properly. Recent research indicates that dosages up to 5,000 IU may provide significant health benefits.
It’s estimated that a significant percentage of adults suffer from vitamin D deficiency. Vitamin D deficiency is associated with a variety of health complications, including rickets (in which bones are unable to properly calcify, or harden) in children, poor prostate health in men and poor bone health in older adults. The elderly, alcoholics and strict vegetarians are particularly at risk for deficiency and should consider regular supplementation. Individuals with darker skin pigments may also be at increased risk, as darker skin contains higher levels of melanin, which may inhibit the skin’s ability to produce vitamin D from sunlight. People with intestinal malabsorption, hyperthyroidism, liver or kidney disease, or pancreatic conditions may be at risk of vitamin D deficiency.