You might need a dose of artificial sunshine

Many people don’t get enough vitamin D, the nutrient produced in the body through sun exposure, recent studies have found. Although the problem is more common in northern climates, even some residents of sunny Southern California are vitamin D deficient. The nutrient is found in eggs, seafood, mushrooms and some fortified milk and cereal, but it’s hard to get enough from food alone -- and supplements are often necessary.

Uses: Vitamin D helps the body absorb calcium from food. Deficiencies contribute to the weakening of bones and an increased risk of bone fracture. People who are over age 65, dark-skinned or overweight are at risk of vitamin D deficiency, as well as anyone who lives in climates without much winter sun. Sufficient vitamin D also might protect against the development of numerous disorders, including cancer, heart disease, diabetes, schizophrenia and multiple sclerosis.

Dose: From 400 international units (for people who get some sun) to 1,000 IUs, daily.

Precautions: Vitamin D should be avoided in doses of more than 2,000 IUs per day because of potential kidney damage. It’s impossible to get too much vitamin D from sun exposure because the body regulates how much it makes on its own.

Research: Studies are exploring whether vitamin D supplements can decrease the rates of cancer, heart disease and diabetes.

Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your health-care provider for advice on selecting a brand.