Use of probiotics and Allergies

An allergy is increasing 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 increase in 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 households with siblings or pets. Healthcare environments and consumption of processed foods have limited the number of microbes in the diet. The hypothesis suggests that children's exposure to microbes before the age of six months helps the immune system mature to be more tolerant to exposure to allergens later in life. Indeed, the microbial colonization of the gut in early life is important for the development of a proper immune system .

Of course, increasing exposure to microbes must be done safely. This hypothesis led researchers in Finland to conduct a study assessing the effects of a strain of Lactobacillus on the incidence of atopic eczema in 132 children at high risk. The study was double-blind, placebo-controlled study.

Given to pregnant women, two to four weeks before delivery, and newborn babies aged six months Lactobacillus rhamnosus GG. They followed the children through two years of age and the incidence of atopic eczema was recorded. The study reported a 50% reduction in incidence of atopic eczema in the group receiving the probiotic supplement .

A complementary study of these same children indicated that these same trends were still present at 4 years of age. However, there was no impact on other allergic conditions with seven years of age. These results suggest that the exposure to the correct types of microbes early in life may decrease the risk of atopic dermatitis . However, a different research group using a similar protocol and the same probiotic microbe Finnish group recently reported that there was no impact on incidence of atopic eczema with the supplement with Lactobacillus rhamnosus GG. In addition, the German study showed a statistically significant increase in cough in the probiotic group. This study questions the validity of the initial observation.