Q: I read that cases of vitamin D deficiency are on the rise. Your column on sunscreens mentioned that exposure to the sun enables the skin to produce vitamin D. Could the widespread use of sunscreens to block out the sun be related to this problem?
A: Sunscreens can thwart the skin's ability to make vitamin D from UV rays, so they could contribute to lower vitamin D levels.
Vitamin D works closely with the mineral calcium in building bone. A deficiency in vitamin D leads to the bone diseases called rickets (in children) and osteomalacia (in adults).
Rickets is associated with bowlegs and other bone malformations.
Osteomalacia is characterized by softened bones. Many people experience muscle or bone pain well before the disease develops.
Vitamin D deficiency was thought to be largely relegated to the past. However, as you point out, there's been an unexpected upswing in cases of this vitamin deficiency in both kids and adults.
What might account for this?
Rickets is more likely to occur in breast-fed babies. Formula is fortified with vitamin D, but breast milk contains only small amounts.
The American Academy of Pediatrics now advises that children, particularly breast-fed babies, be prescribed vitamin D supplements through adolescence.
Adults, hearing continuous warnings about the dangers of UV rays from the sun, including skin cancer and premature aging and wrinkling of the skin, may be shunning the sun or wearing protective clothing and slathering on sunscreen.
Besides sun exposure, you can get vitamin D from diet and vitamin supplements.
The recommended daily amounts for vitamin D are based on age as follows:
- Birth through age 50 years: 200 IU.
- Ages 51 to 70 years: 400 IU.
- Over age 70: 600 IU.
It's difficult to meet your vitamin D needs from diet. Only a few foods, such as fatty fish, naturally contain vitamin D. The most common dietary sources, vitamin D-fortified milk and foods, are likely to leave you short.
Standard multivitamin products provide 400 IU of vitamin D, and other vitamin D products are available in higher amounts. So you can readily meet your vitamin D needs this way.
That said, have we perhaps gone overboard on the decree to avoid sun exposure? In fact, to sun or not to sun has become a simmering controversy.
Sun exposure provides up to 80 or 90 percent of vitamin D stores in the body.
And it doesn't take much time in the sun to produce enough vitamin D. Exposing the face and arms to the sun two to three times a week for only five to 10 minutes at a time seems to do the job.
Vitamin D supplementation may be needed for those with inadequate sun exposure, including many elderly people, those living in northern latitudes, and dark-skinned individuals (the skin pigment melanin competes for the UV rays needed to produce vitamin D).
People taking extra calcium to prevent osteoporosis also need adequate amounts of vitamin D to enhance calcium absorption.
(Richard Harkness is a consultant pharmacist and specialist in natural therapies. Write him at 1224 King Henry Drive, Ocean Springs MS 39564; or email@example.com. Selected questions will be used in the column.)
(c) 2004, The Sun Herald (Biloxi, Miss.). Distributed by Knight Ridder/Tribune News Service.