Vitamin D and sunshine go together. Among other ailments, a D deficiency increases the risk of “adult rickets” or osteomalacia, a painful bone disease that can lead to muscle weakness, bone pain and bone fracture.

Osteomalacia, according to Dr. Michael Holick, director of the Vitamin D, Skin and Bone Research Laboratory at Boston University, is often misdiagnosed as arthritis or fibromyalgia. Many patients with aching bones and muscles, Dr. Holick points out, are often simply suffering from a lack of D vitamins.

Insufficient sun exposure and D deficiencies are also linked to multiple sclerosis, congestive heart failure, high blood pressure and some cancers, including non-Hodgkin’s lymphoma (NHL). A recent study published in the International Journal of Cancer shows that people with the highest sun exposure had 35% less NHL.

Scientists have also known for some time that Caucasians, when compared to darker skinned ethnic groups worldwide, have a much lower diabetes 2 risk. They believe this is due to white skin’s greater sensitivity to sun exposure. A recent study, for example, showed that people with white skin and a high D vitamin level had one quarter the risk of diabetes than those with low levels.

Ten minutes to as much as an hour and a half of sunlight two or three times a week for darker skinned people should be sufficient to produce adequate vitamin D. The best food sources of D are dairy products, organ meats (liver), egg yolks, cod liver oil and seafood, particularly halibut, salmon and tuna.

Since the 1930’s, authorities have recommended limiting D vitamin intake to less than 2,000 I.U. a day. But recent studies show that at least 5,000 I.U. and up to 10,000 I.U. a day are safe and healthy. “It’s virtually impossible to get that much from diet,” Dr. Holick says. “And there’s never been a reported case of D toxicity because of too much sun.”

So, if you’re stuck inside all day, have dark skin or live north of Atlanta or Los Angeles, where there’s just not enough sunlight from November through February, be sure to supplement your diet with vitamin D. Dr. Holick recommends at least 1,000 I.U. daily. Typical multiple vitamin supplements usually have only about 400 I.U.’s.