Probiotics Do Not Have a Significant Impact on Preventing Eczema, Asthma in Infants

Probiotics are often believed to stimulate healthy immune function by increasing the defensive action of the cells that line the gut and inhibiting the growth of viral and bacterial pathogens. However, a new study from researchers at the University of California, San Francisco (UCSF), did not find significant evidence that a supplement of lactobacillus prevents eczema, which is a common precursor to asthma.

The study, published in Pediatrics, compared the effects of the probiotic on children who received it within the first 6 months of life and those who had not in order to see if the probiotic would lessen the risk of eczema and asthma.

“On the basis of the hygiene hypothesis, which suggests that the absence of infectious exposure at a critical point in immune system development could lead to greater risk of allergic disease, it is thought that probiotic exposure could theoretically affect immune system development and reduce the subsequent risk for the development of allergic disease,” the authors wrote.

All children included in the research had one or both parents with asthma, meaning they were at high risk of developing the disease as well—from either hereditary or environmental factors.

Pregnant women were recruited into the study and within 4 days of birth, the infant was randomly assigned to receive either a daily capsule of 10 billion colony-forming units of Lactobacillus rhamnosus GG supplement and 225 mg of insulin for the first 6 months of life or a daily capsule containing 325 mg of insulin for the same period of time. The control and intervention capsules appeared, tasted, smelled, and felt the same and parents were not told which they were receiving.

“One theory is that the absence of infectious exposure at a critical point in immune system development leads to a greater risk for eczema and asthma. Additionally, lack of key bacteria in the infant intestinal microbiota has been associated with the later increased risk of allergic disease,” Michael Cabana, MD, director of the division of general pediatrics at UCSF Benioff Children’s Hospital San Francisco, and the author of an accompanying editorial, said in a statement. “Supplementing with specific probiotic strains may modify the entire microbiota community patterns and decrease this risk.”

Of the 184 infants in the study, half of them received the probiotic capsules and the other 92 received placebo capsules. But, the researchers did not find a significant difference between the groups: 30.9% of the placebo recipients were diagnosed with eczema at age 2, while 28.7% of the probiotic group were diagnosed.

The study also notes that other factors may be contributing to the difficulty in identifying the protective effects of the probiotics. For instance, the researchers found that 51% of probiotic recipients and 45% of placebo recipients were breastfeeding. Therefore, it is more challenging to decipher if the benefits are a result of the breast milk or the probiotic.

“What we don’t know yet is which bacteria are most beneficial, what they produce that mediates the benefit and how best to introduce them to babies,” said co-senior author Homer Boushey, MD, of the UCSF Department of Medicine. “What our study shows is the feasibility of introducing one potentially beneficial microbe. This is just an early step on what will likely prove a long journey.”