Children who take probiotics - the "good" bacteria that live in the guts - are less likely to develop eczema, a review has found.
Infant eczema is a common, non-contagious skin disorder that causes intense itching. Its cause is unknown, but some theories have implicated allergies or intolerance to certain food.
The study by researchers from the University of California, Davis, published in the Archives Of Dermatology, said one in five children experiences eczema. The researchers had collected the results of 21 studies on attempts to prevent or reduce eczema symptoms through nutritional supplements. Some of the 11,000 participants were infants and others were expectant or breastfeeding mothers.
Ten of the studies experimented with giving probiotics to some of the participants and placebos to other participants. Probiotics are microbes, primarily bacteria, that live in the intestine and aid digestion. They are present in food such as yogurt.
A few studies - in which children at risk of developing eczema were given the bacteria lactobacillus rhapsodic GG or lactobacillus rhamnosus strain HN001 - found that the children's chances of developing eczema were half that of those given the placebo. Several other studies that gave mixtures of probiotics to children also found the risk for eczema was at least halved.
Not all probiotics seemed to work, however. And when the researchers looked at studies of other kinds of supplements, results were mixed.
Of the studies they reviewed on prebiotics - dietary components that promote the growth of good bacteria in the intestine - two found that the supplements helped reduce eczema, but one found no change in the severity of eczema in children who had it.
Similarly, some studies found fewer cases of eczema among those on special types of infant formula (hydrolysed or amino acid-based) while others found no difference in the severity of the skin rash.