The allergy is rising in industrialized nations. It is estimated that the incidence of asthma in the United States doubled between 1980 and 2000. Scientists have proposed a hypothesis known as the hygiene hypothesis to explain the rise of allergic conditions such as asthma and eczema. This hypothesis is based on observations that a lower incidence of allergy is associated with environments that have higher numbers of microbes, such as day care centers, farms, or in homes with siblings or pets. The consumption of processed foods and healthcare environments have limited the number of microbes in the diet.
They followed the children through two years of age and the incidence of atopic eczema was registered. The study reported a 50% reduction in incidence of atopic eczema in the group that received the probiotic supplement. A complementary study of these same children indicated that these same trends they were still present at 4 years of age. However, it was not observed any impact in other allergic conditions at seven years of age. These results suggest that the exposure to the right in microbes types early in life can decrease the risk of dermatitis atopic. However, a diverse group of research using a very similar protocol and the same probiotic Microbe that the Finnish group, recently reported that it was not observed any impact on incidence of atopic eczema with supplementation with Lactobacillus rhamnosus GG. In addition, the German study noted a significant statistical increase in coughing in the probiotic group. This study question the validity of the initial observation.