Vitamin D is made in the skin when exposed to summer sunlight (UVB), or obtained from a few certain foods eaten or taken as a supplement.

Vitamin D is needed in the body to raise blood levels of 25-hydroxyvitamin D (25 (OH)D), which are associated with healthy bone, muscle, breast, heart, colon and immune system.

Research findings show a 25 (OH)D blood level above 30 ng/mL is related to better health and less risk of disease. A vitamin D3 supplement may be especially helpful for anyone who avoids exposing skin to sunshine.