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NEW YORK (Reuters Health) - Children who take a supplement of probiotics - those "good" bacteria that live in our guts - are less likely to develop eczema, according to a new review of studies.
"I'm hoping researchers will continue to study these supplements to see if their findings can contribute to new therapeutic options for infants predisposed" to eczema, said Negar Foolad, the lead author of the study and a graduate student at the University of California, Davis.
Infant eczema, also called atopic dermatitis, is a common, non-contagious skin disorder that causes intense itching.
According to Foolad's study, published in the Archives of Dermatology, one in five kids experiences eczema.
Dr. Sonia Michail, an associate professor at the University of Southern California and the Children's Hospital of Los Angeles, said the cause of the skin problem is unknown, but that some theories have implicated allergies or intolerance to certain foods.
To gauge what the research has found in attempting to prevent or reduce the symptoms of eczema through nutritional supplements, Foolad and her colleagues - one of whom is a consultant to companies that market such supplements - collected the results of 21 studies, including 11,000 participants.
Some of the people in the studies were infants and others were pregnant or breastfeeding mothers.
Ten of the studies experimented with giving probiotics to some of the participants and a fake supplement to other participants.
Probiotics are microbes, primarily bacteria, that live in the intestine and aid digestion. They are present in some foods, including yogurt.
A few studies in which children at risk for developing eczema were given the bacteria Lactobacillus rhapsodic GG or Lactobacillus rhamnosus strain HN001 found that the kids' chances of developing the skin condition were cut in half compared to kids given the placebo supplement.
In addition, several other studies that gave mixtures of probiotics to children also found the risk for eczema was at least halved.
"It is intriguing to learn that probiotics, which can only be present inside the intestine, are able to remotely affect the skin," said Michail.
LIMITED EVIDENCE FOR OTHER SUPPLEMENTS
Not all probiotics seemed to work, however. And when Foolad and her colleagues looked at studies of other kinds of supplements, results were mixed.
Of the studies Foolad's group reviewed on prebiotics - dietary components that promote the growth of good bacteria in the intestine - two found that the supplements helped reduce eczema, while one found no change in the severity of the skin condition among kids who already had it.
Similarly, with studies of special types of infant formula - either hydrolyzed or amino acid-based formula - some found a reduction in the number of cases of eczema, while others found no differences in the severity of the skin rash.
A few studies supplemented children or moms with omega-6 fatty acids, and the jury remains out on whether they can prevent eczema.
"It's hard to come to a conclusion about prebiotics and amino acid based (infant) formulas and black currant seed oil because there weren't a lot of studies" on them, Foolad told Reuters Health.
Michail pointed out that the best evidence for now lies with supplements of the probiotic Lactobacillus rhamnosus GG.
"Even though research has shown some benefit for nutritional supplementation in (atopic dermatitis), however, supplements have not been widely used for management" of the condition, she said.
Lactobacillus rhamnosus GG supplements are available in powdered or chewable forms marketed to kids, and they sell for about $30 for 30 packets.
Foolad said these aren't necessarily the formulations used in the studies.
Michail added that the benefits of the probiotics are modest, and the long term effects of supplementing children with the bacteria have not been studied adequately.
SOURCE: bit.ly/XKg3hy Archives of Dermatology, online December 17, 2012.