Summary of Vitamin D Primary information, health benefits, side effects, usage, and other important details

It is invalid to extrapolate from efficacy against the common cold or respiratory tract infections broadly to the novel coronavirus in particular. For more information, see this page.

Vitamin D is a fat-soluble nutrient. It is one of the 24 micronutrients critical for human survival. The sun is the major natural source of the nutrient, but vitamin D is also found naturally in fish and eggs. It is also added to dairy products.

Supplemental vitamin D is associated with a wide range of benefits, including increased cognition, immune health, bone health and well-being. Supplementation can also reduce the risks of cancer, heart disease, diabetes and multiple sclerosis. People deficient in vitamin D may also experience increased testosterone levels after supplementation.

The body produces vitamin D from cholesterol, provided there is an adequate amount of UV light from sun exposure. There is only a sufficient amount of UV light coming from the sun when the UV index is 3 or higher, which only occurs year-round near the equator, between the 37th parallels.

Most people are not deficient in vitamin D, but they do not have an optimal level of vitamin D either. Due to the many health benefits of vitamin D, supplementation is encouraged if optimal levels are not present in the body.