Vitamin D is an important vitamin that is hard for humans to absorb; it is primarily made in the skin, when it is exposed to sunlight. As people have migrated towards more indoor activities, vitamin D must be obtained mainly from nutritional or supplemental sources.
Vitamin D supports calcium metabolism, and both of these nutrients are critical for bone health throughout life. Additionally, vitamin D has recently been shown to support heart and skin health; weight management; cell differentiation and wound healing/immunity; provide protection for a number of cancers; regulate insulin secretion; plus protect against arthritis symptoms, flu, cognitive decline, depression and menopause symptoms. In children, a severe vitamin D deficiency results in bone deformities known as rickets.