Probiotics and fish oil supplements during pregnancy and breastfeeding may reduce the risk for food allergies and eczema in early childhood, researchers report.

In a review of hundreds of studies, they found 19 randomized controlled trials with strong evidence showing that compared with no supplements, probiotics taken after the 36th week of pregnancy and the first months of lactation were associated with a 22 percent reduction in the risk for eczema in children.

They also analyzed six randomized trials with solid evidence that women who took omega-3 fatty acid supplements during pregnancy and lactation reduced the risk for childhood allergic reaction to eggs, the most common food allergy, by 31 percent.

The meta-analysis, in PLOS Medicine, found no evidence that avoiding certain foods or taking vitamin and mineral supplements during pregnancy had any effect on childhood eczema or food allergy.

Fish oil has known anti-inflammatory effects, which could explain why it may reduce the risk for food allergies, but the reasons for the possible effect of probiotics on the risk for eczema is unknown.