Probiotics are getting plenty of attention these days regarding their potential health benefits. The general idea is that by introducing “good” bacteria to the gut you can somehow modify disease states. In the medical community, the idea started to take hold with the advent of the “hygeine hypothesis”, a theory which held that childhood exposure to common infections could reduce allergic sensitization. Researchers then noticed that children from Estonia, where there is a very low incidence of eczema, had higher levels of the “good” bacteria, lactobacillus, in their stool, than did children from Sweden, where there is a much higher incidence of eczema. (I’m just glad I didn’t have to do my fellowship in Estonia.)
In the years that followed, numerous trials have been done looking at the effect of probiotic supplementation on allergic disease, including this excellent study from New Zealand published in this month’s Journal of Allergy and Clinical Immunology. The results have been mixed and are complicated by the fact that numerous probiotic bacteria species have been used and the timing of supplementation has varied greatly. The take home message is this:
- Not all probiotics are created equal. Lactobacillus rhamnosus is the species most often found to be effective.
- In high risk subjects- those with a strong family history- L rhamnosus reduced the relative risk of eczema by around 50%, from an absolute risk of 28% down to 14%. Another way of putting it is that 8 kids would have to be treated to prevent one case of eczema.
- Supplementation has worked best when done during pregnancy and breastfeeding by mom and for the first 2 years of the child’s life.
- Despite the reduction in eczema, probiotic supplementation has consistently been shown to not reduce the incidence of either food or inhalant allergies.
Prevention of disease should always be the first goal of medicine. Based on this recent study and others, I think there is enough information to support probiotic supplementaion for the prevention of eczema in high risk individuals.