BOSTON -- New products are serving more bacteria -- and experts said that may be good.

"Healthy bacteria are bacteria that normally live in your GI tract that help you maintain immune function," said Dr. Caroline Apovian of the Boston Medical Center.

Small amounts of healthy bacteria or "probiotics" are already in some milks, yogurts, bananas and artichokes -- and some other products in which they're additives.

"We noticed an interest and expanded a number of the products (we offer). Our customers tell us that they really love them. They ask for them," said Bailey Stoler, a supermarket chain marketing representative.

Dannon has started stocking Danactive on the shelves, which is a dairy drink that contains probiotics. Stonyfield Farm has added six live, active cultures to all its yogurts.

"We've seen in studies that probiotics can help people who don't have enough healthy bacteria get better," Apovian said.

A new study in the journal Environmental Health found eating more probiotics may be beneficial. In the study, 181 factory workers in Sweden were given a drink every day.

"Those who took this product had less sick days than those who did not," Apovian said.

Apovian stressed that more studies need to be done and on a larger scale to confirm what, if any, benefits there are when it comes to taking in extra healthy bacteria.

Doctors recommend that people who have compromised immune systems -- such as the elderly -- only take probiotics after first consulting their doctor.