Parents desperate for a treatment for their baby’s colic may want to try a little bacteria – a lot of little bacteria.

Researchers in Italy have found that the probiotic Lactobacillus reuteri showed great promise as a cure for colic. Probiotics are bacteria found to be beneficial to humans. They are commonly found in such products as yogurt or kefir, and can be purchased as supplements. But the various benefits of probiotics have been attributed only to specific strains of bacteria, often making it difficult for consumers to track down the treatment.

The researchers, from the University of Turin, tested the effect of Lactobacillus reuteri using a formulation from Swedish manufacturer BioGaia. They recruited parents of 83 colicky babies who were exclusively breast-fed. Half received five drops of the probiotic in an oil suspension 30 minutes after feeding. The other half received simethicone, a pharmaceutical product often used to treat colic but found no more effective than a placebo.

Both groups of babies cried an average of 197 minutes per day at the start of the study. But by the end of the four-week study, the infants receiving probiotics cried only 51 minutes a day, while the simethicone babies were still crying an average of 145 minutes per day.

According to the parent logs, the symptoms of colic began to subside within a week of beginning treatment. Some 95 percent of infants in the study responded to the probiotics, compared with only 7 percent responding to simethicone.

Colic, characterized by excessive, inconsolable crying without an identifiable cause, is one of the most common problems of infancy, affecting as many as a quarter of children under the age of 3 months. Researchers have discovered that colicky babies have lower counts of intestinal lactobacilli, a healthy bacteria that aids in digestion, than healthy babies.

Lactobacillus reuteri has been used safely as a probiotic supplement in adults for years and recent data showed that it is safe in use for newborn infants. According to the BioGaia Web site, the formulation used in the study is available in 10 countries and will be launched in 17 additional countries this year. It could not be confirmed when the drops will be available in the U.S.

The researchers said it wasn’t clear how the probiotics help, whether through a shift in the balance of the intestinal tract towards more healthy bacteria, or by boosting the immune system.

While the study looked at only breast-fed infants, it builds on a previous study conducted at Johns Hopkins University with formula-fed babies. That study used the probiotics Bifidobacterium lactis and Streptococcus thermophilus added to formula. Parents reported significantly fewer episodes of colic and irritability with both probiotics.

Formulas containing those strains have been marketed in Europe, Asia and South America for years without any known adverse effects.