In a Finnish study appearing in the May 31 issue of The Lancet, researchers conclude that children exposed to probiotics before birth were 40 percent less likely to have eczema, an allergic skin disease. They didn't lessen the chances of developing allergies or asthma, however.

"Early modification of the immune system by probiotics may have a preventive effect on the development of atopic eczema, at least in high-risk children," says study author Dr. Marko Kalliomaki, a resident in pediatrics at Turku University Central Hospital in Turku, Finland.

The findings add another piece to support the "hygiene hypothesis" in the ongoing debate about what is causing the rise in allergic diseases such as asthma and eczema. The hygiene hypothesis is a theory, originally proposed about 10 years ago, that blames the increase in allergic disease on cleaner living. Because children's bodies don't have to fight off as many bacteria as they did in the past, their immune systems start mistakenly attacking harmless substances, such as pet dander or pollen, causing allergic diseases.

For this study, the researchers hoped that if they introduced a "good" bacteria, they could stimulate the immune system properly and lessen allergic reactions.

Kalliomaki and his colleagues recruited 159 mothers-to-be in Turku for the study. All of the women had a personal or family history of asthma, allergies or eczema.

Beginning two to four weeks before delivery, the mothers were randomly assigned to take either two capsules containing the probiotic Lactobacillus rhamnosus GG or two capsules of a placebo daily until their babies were 6 months old if they were breast-feeding. Babies who weren't breast-fed were given the contents of the capsules mixed with water until they were 6 months old.

The researchers saw the children again at 2 and 4 years of age to look for signs of allergic disease. One hundred and seven children completed the full four years.

Of those, 14 out of 53 who received probiotic treatment were diagnosed with eczema, compared to 25 out of 54 children who had received a placebo.

"Early probiotic supplementation may have profound and long-lasting effects on the development of eczema," Kalliomaki says.

There was no significant difference between the groups when it came to the development of asthma and allergies, however.

Dr. Michael Wasserman, a pediatrician at Ochsner for Children in New Orleans, says this study provides "fairly good statistical evidence that the early introduction of Lactobacillus has some benefit."

But he cautions that probiotics have not been well studied in children. Though there don't appear to be any side effects from the treatment, he says safety can't be assumed, especially because this study was done on a small and relatively homogenous group of people.

The probiotic treatment used in this study looks "promising and safe," Wasserman says, but he adds there needs to be a larger study done confirming the benefits and safety.

Wasserman recommends talking with your health-care provider before making any major changes in your child's diet.

"Just because something is natural doesn't mean it's safe. Remember, arsenic and cyanide are natural," Wasserman says.

More information

To learn more about probiotics, visit the American Dietetic Association. For more information on eczema, read this article from the American Academy of Pediatrics.