Having a high diversity of bacterial species in the gut may protect babies against developing allergies, according to a comprehensive study of intestinal microflora in allergic and healthy infants conducted in Sweden. Stool samples were analysed at one month of age from 20 children with IgE-associated eczema, as well as from another 20 healthy controls. The researchers then used DNA sequencing to identify the bacterial species in the samples. The results showed that gut microflora diversity at one month was significantly greater in healthy children, compared to those children with atopic eczema. The authors results help substantiate the ‘hygiene hypothesis’, which suggests that early exposure to environmental allergens reduces the risk of developing allergies. They suggest that the composition of intestinal microflora during the first weeks of life is critical to the development of the infant immune system. In the absence of sufficient stimuli from a wide variety of bacteria, the immune system may overreact against harmless antigens in the environment, such as foods. (Low diversity of the gut microbiota in infants with atopic eczema. J Allergy Clin Immunol. 2011 Dec 6. [Epub ahead of print]).