What factors influence the synthesis of vitamin D in the skin?
A. The synthesis of vitamin D in your skin is affected by where you live and the season. The further north you go, especially during the winter, the less vitamin D is made in the skin. Here in Oregon at around the 45th parallel, you’re not going to produce much. If you live in Los Angeles, you can synthesize vitamin D year round. Sunscreen blocks vitamin D synthesis. The darker the skin, the longer you need to spend in the sunlight. As you get older, your skin becomes less efficient at synthesizing vitamin D, probably due to a reduction in the cholesterol substrate. Q. How widespread is vitamin D deficiency? A. It’s estimated that about 10% of Americans are deficient and that 70% are insufficient. Q. The litany of diseases that vitamin D may help prevent is long and includes cancer, heart disease, diabetes, multiple sclerosis, hypertension, autoimmune diseases like rheumatoid arthritis, and infections. How can vitamin D be effective in preventing so many different diseases? A. One conn
