Vitamin D is typically associated with sunshine, since just 10 to 15 minutes in the sun can stimulate the body to produce the daily requirement of the nutrient.
The chief role of vitamin D is to facilitate calcium absorption and build bone density. A fat-soluble nutrient, vitamin D can be stored within fat cells for long periods of time.
How much you should have: The current recommended daily dosage of vitamin D is 200 to 400 IU. Vitamin D is especially important for the elderly. Men and women over the age of 70 should get at least 600 IU per day. Newer studies suggest that as many as 1,000 IU per day may be optimal for adults.
One study hypothesized that women should consume up to 2,000 IU of vitamin D during pregnancy. Consuming more than 2,000 IU per day has - up until now - been considered potentially dangerous. At any rate, speak with a nutritionist or physician before making any dramatic dietary changes.
Dwellers in northern climates may wish to take vitamin D supplements during the winter, when the body creates the least amount of the vitamin.
Individuals with darker skin - and therefore higher melanin levels - produce up to 90 percent less vitamin D that people with paler skin.