Vitamin D is a fat-soluble vitamin. Fat-soluble vitamins are stored in the body's liver and fatty tissues. Vitamin D acts as both a vitamin and a hormone.

Vitamin D is found in some foods, but the main sources are vitamin D-fortified milk and sunlight. The ultraviolet rays of the sun react with cholesterol present on the skin and create previtamin D3. This compound goes through a series of reactions in the kidneys and the liver, and the final product is vitamin D.

Vitamin D's functions:

  • Plays a crucial role in the growth and maintenance of strong, healthy bones
  • Maintains normal blood levels of calcium and phosphorus

In children with low vitamin D levels, the supplement can improve bone mineral density. While the evidence does not give a clear answer, it has also been suggested that vitamin D supplementation may reduce the risk of osteoporosis and seasonal flu in children, and high blood pressure and some forms of cancer.

Vitamin D has also been found to improve pain symptoms in patients with low vitamin D levels.