Q:

What's your opinion on taking a selenium supplement? I've been taking one, but now I'm hearing that it might not be such a good thing.

- M.C., Wilkes-Barre
A: Beyond the selenium content in food and a multivitamin you may be taking, I would not advise taking extra selenium. While selenium is a known antioxidant that has been previously thought to protect against cancer and heart disease, several recent studies suggest that too much selenium may be harmful.

One study in the Aug. 21 issue of the Annals of Internal Medicine showed that folks receiving 200 micrograms of selenium daily may have a higher incidence of diabetes. Another recent study from the University of Warwick, England, found that taking too much selenium or consuming too much dietary selenium was associated with an 8 percent rise in total cholesterol and a 10 percent rise in triglyceride and LDL "bad" cholesterol levels. This could raise the risk of heart disease.

Public health experts at the Johns Hopkins School of Public Health point out that 99 percent of the U.S. population have blood selenium levels that are more than 95 ng/ml, a level beyond which additional selenium cannot exert any further antioxidant effects. So even if selenium supplementation isn't harmful, it likely isn't needed.

Food sources that are naturally high in selenium include: corn, wheat, and rice cereals; nuts (especially Brazil nuts and walnuts); beans; red meat and seafood (especially tuna and cod); eggs; cheese; oats; and turkey.

Q: I have a burning sensation in my mouth, when I brush my teeth. I've changed toothpaste, but it does no good. I cannot eat spicy or hot foods. My doctor said it's from a yeast infection in my mouth. He gave me some medicine that I suck on like a lozenge. Could it be from my diabetes medication?

- D.H., Waynesfield, Ohio
A: The burning you're describing is due to irritation of the delicate tissue lining of your mouth. It's not caused by your diabetic medication but by your blood sugars being too high.

This yeast infection is from the fungal organism Candida albicans, also known as thrush. This is the same organism that causes vaginal yeast infections.

Yeast is normally present in the mouth and vagina, in numbers too small to be of consequence. Normal, healthy bacteria in our mouths and the vaginal cavity keep the fungal population under control. But if there's some sort of disruption in the balance of things, fungal (Candida) overgrowth can occur. It's observed as creamy-white patches in the mouth (especially the tongue) that can't be scraped off, or a curd-like material in the vagina.

When blood sugars are too high, there's more sugar in the saliva. Fungi love sugar and thrive on it like fertilizer. To properly treat thrush in a diabetic, blood sugars need to be brought under control.

Thrush is treated with antifungal medicine in the form of lozenges, rinses, and pills. To soothe the raw mouth tissue, hold low-fat yogurt, cold milk, or ice cream in your mouth; chill your food before eating it; suck on crushed ice; avoid hot liquids; use milder children's toothpaste, rinse your mouth with liquid antacid; and avoid spicy, hot, salty, or vinegar-containing foods, and acidic foods such as citrus and tomatoes.

Mitchell Hecht is a physician specializing in internal medicine. Send questions to him at: "Ask Dr. H," Box 767787, Atlanta, Ga. 30076. Because of the large volume of mail received, personal replies are not possible.