More research needed into infant probiotics

Medical Tribune June 2008 SF7

David Brill

Probiotic drinks could help to stimulate the development of a newborn baby’s immune system but more research is required to fully understand their effects, a leading pediatrician has advised.

After birth, the immature gut is rapidly colonized by millions of different bacteria. The composition of this new ecosystem only becomes fixed after around 6 months – offering a window in which a baby’s immunological development could, theoretically, be influenced.

Whether this effect can be achieved by giving probiotic bacteria to infants is not yet clear, according to Bengt Björkstén, professor emeritus of pediatrics and allergy prevention at the Karolinska Institutet, Sweden.

“I think that’s the future. I don’t think we are there yet,” he explained, speaking ahead of the first regional Nestle Nutrition Institute Symposium, held last month in Singapore. “We need to learn more about the colonization process and which [bacteria] are truly beneficial and which are less beneficial.”

In the absence of this evidence, Björkstén believes that mothers should make their own decisions as to whether to give probiotics to their infants. “But I can honestly say
that I don’t see any downside,” he added.

Björkstén also stressed that consumers should be wary when buying probiotic drinks, as many contain bacteria for which there is no documented health benefit. Only three strains of lactobacillus (L. plantarum, L. reuteri and L. rhamnosus GG) and certain strains of bifidobacteria (particularly BB12) appear to be beneficial, he said.

These sentiments were echoed by Dr. Patricia Conway from the School of Biotechnology and Biomolecular Science at the University of New South Wales, Australia.

“Choose the probiotic wisely. Look for the strain identifier,” she advised. “If it does specify which one it is, the consumer can go on Google and find out what evidence there is for that particular strain.”

Probiotics could prove to be of particular benefit to babies born by cesarean section and those who are not breastfed, as they receive less exposure to maternal bacteria during their first months. Research has shown that even at 1 month of age, these babies have less so-called “good bacteria” and more “bad bacteria” in the gut than those who were born vaginally and breastfed.
[Pediatrics 2006 Aug;118(2):511-21]

Cesarean-born babies also appear to have a slight but significantly increased risk for allergies, according to Björkstén, although it remains theoretical as to whether this results from differences in gut microbial profiles.

“It is a hypothesis but it’s a reasonable hypothesis,” he concluded.