Question: : I have to use insect repellent every time I go outside. When I also need sunscreen, which goes on first?
Answer: : This straightforward question has no simple answer. The Centers for Disease Control and Prevention recommend that "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. It points out that "DEET-containing insect repellents may decrease the effectiveness of sunscreens and sunscreens may increase absorption of DEET through the skin."
We also discovered research demonstrating that DEET and the sunscreen ingredient oxybenzone (benzophenone-3) mutually increased skin absorption (Toxicology and Applied Pharmacology, Sept. 1, 2007). 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.
Question: : A gentleman wrote you that he had been taking a prescription heartburn pill for years. Through his own research he learned that he might have a B-12 deficiency due to his use of the drug over an extended period of time. He had symptoms such as fatigue and mild depression.
Upon reading the article, I realized that I had similar symptoms and was taking Nexium. I saw the doctor for a routine blood work-up, and he checked the B-12 level. It turned out that I was extremely deficient! The nurse called immediately, and I was put on a protocol of monthly shots.
When I visited my gastroenterologist, he said he had never heard of such a thing. I was quite surprised and would like to educate him.
Answer: : This issue has been controversial for years, but there is growing recognition that long-term use of powerful acid-suppressing drugs can interfere with vitamin B-12 absorption (American Journal of Gastroenterology supplement, March 2009).
Calcium, iron and vitamin B-12 are all more readily absorbed from an acid environment. The blood tests for vitamin B-12 deficiency should include a measurement of methylmalonic acid (MMA) and not just serum vitamin B-12.
Question: : I suffered from chronic hives for years without much help from the allergist or the dermatologist. The medicines they prescribed did little to relieve my symptoms and left me in a fog. I was becoming a hermit.
