Q. Should my kids take probiotics—and if so, when?

A. These "friendly" bacteria, such as Lactobacillus acidophilus and Bifidobacterium, promote good health by aiding digestion, boosting immune function, and treating diarrhea, food allergies, eczema, and even the common cold.

Probiotics can be especially helpful for children who are lactose intolerant or tend to have digestive upset. They are extremely safe, so there's nothing wrong with long-term, daily use. Probiotics also fit the bill for occasional short-term use when diarrhea hits, during the use of antibiotics (to reduce the risk of diarrhea), while traveling internationally, or in the midst of cold and flu season (Journal of Pediatric Health Care, 2003, vol. 17, no. 6).

Although they can be pricey, probiotic supplements are potent enough to be dependably effective. Many products provide upward of 10 billion cells in one capsule! Another plus: Probiotic supplements lack the high sugar content of many kids' yogurts (which can contain 4 teaspoons of sugar in just 4 ounces). Excess sugar consumption suppresses the immune system.

Yogurts or kefirs certainly can be good choices as well, but be sure your child eats 4 ounces per day of a product labeled with the "live & active cultures" seal, which ensures that it contained at least 100 million cultures per gram at the time of manufacture.

When giving probiotic supplements to small children or babies, it's easiest to sprinkle the powder from a capsule into yogurt or another food that's not heated. Or try sugar-free chewable tablets.

This Q&A was written by Victoria Dolby Toews, MPH, a health journalist based in the Pacific Northwest, where she and her family enjoy hiking and cycling.

Young RJ, Huffman S. Probiotic use in children. Journal of Pediatric Health Care, 2003, vol. 17, no. 6, p. 277-83. Great review; full text available here for fact checkers: http://www.medscape.com/viewarticle/464550_1