Summer skin care's absorbing problem

Q: I have to use insect repellent every time I go outside. When I also need sunscreen, which goes on first?

A: This straightforward question has no simple answer.

The Centers for Disease Control and Prevention (CDC) recommend: "Sunscreens should be applied to the skin before insect repellents." In the next sentence, however, the CDC advises travelers not to use combination products containing both repellents and sunscreens.

DEET-containing insect repellents may decrease the effectiveness of sunscreens, the CDC says, while sunscreens may increase the skin's absorption of DEET.

We also found research showing DEET and the sunscreen ingredient oxybenzone (benzophenone-3) mutually increase skin absorption. Since oxybenzone has estrogenic activity, increased absorption is not desirable.

If you use a sunscreen that relies on zinc oxide or titanium dioxide, this should not be a concern.

For more about sunscreen safety, we are sending you our new Guide to Skin Care and Treatment. Anyone who would like a copy, please send a $3 check or money order with a long (No. 10), stamped (61 cents), self-addressed envelope to: Graedons' People's Pharmacy, No. S-28, P.O. Box 52027, Durham, NC 27717-2027. It also can be downloaded for $2 from our Web site: www.peoplespharmacy.com.

Q: A man wrote you that he had learned he might have a B-12 deficiency from use of a prescription heartburn pill for years. He suffered from fatigue and mild depression.

I realized I had similar symptoms and was taking Nexium. When the doctor checked, it turned out I was extremely B-12 deficient, and I was put on a protocol of monthly shots.

My gastroenterologist said he had never heard of this.

A: There is growing recognition that long-term use of powerful acid-suppressing drugs can interfere with vitamin B-12 absorption. Calcium, iron and vitamin B-12 are all more readily absorbed from an acid environment. The blood tests for B-12 deficiency should include a measurement of methylmalonic acid (MMA) and not just serum vitamin B-12.

In their column, Joe and Teresa Graedon answer letters from readers. Write to them c/o King Features Syndicate, 300 W. 57th St., 15th floor, New York, NY 10019, or via their Web site: www.peoplespharmacy.org