Vitamin D is not really a vitamin, but is an essential hormone. It forms in the skin of humans and some animals that are exposed to sunlight and have the capacity to make vitamin D.

“We estimate that vitamin D deficiency is the most common medical condition in the world.” – Dr. Michael F. Holick, vitamin D expert

In humans, the vitamin D hormone is critically important for the development, growth, and maintenance of healthy body function, throughout the lifespan. Vitamin D’s metabolic product, 1,25-dihydroxyvitamin D (calcitriol), is the key which unlocks binding sites on the human genome (DNA). Thehuman genome contains more than 2,700 binding sites for calcitriol, which may play a role in the prevention of major chronic disease of humans.

A little bit of vitamin D has a major effect. It is measured in International Units (IU) – one IU is equal to only 0.000025 milligrams (mg)!