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Friday, May 6, 2011

A look at commensal gut bacteria, probiotics and atopy and obesity

In a clinical review in this month’s issue, Ly et al. (J Allergy Clin Immunol 2011;127:1087-1094) pull together what is known currently about gut microbiota influence on immunity, the association of abnormal microflora with eczema, asthma and obesity, the usefulness of probiotics for normalizing commensal gut bacteria, and newer information about vitamin D interactions with intestinal flora.

The authors begin commenting on how infants achieve gut colonization peri- and post-natally and note that vaginal delivery results in different gut flora in the infant than cesarean delivery. In particular, infants delivered by cesarean establish gut flora dominated by Klebsiella and Clostridum species, and enterobacteria other than E. coli, with later and less colonization by Bacteroides sp. and Bifidobacterium sp. Ly et al. point out that hospitalized neonates have gut flora similar to infants delivered by cesarean, suggesting that standard of care antibiotic use could be related to the decreased colonization by healthy bacteria.

They continue with a review of current knowledge of differential gut microbial populations between atopic and non-atopic infants, noting that atopic infants have lower fractions of lactobacilli, bifidobacteria, and Bacteroides sp. than their non-atopic counterparts. Ly et al. comment that current studies on neonatal gut commensalism and atopy are inconclusive, then discuss the design variability and limitations that result in contradictory findings.

The authors move to the evidence supporting a relationship between disturbance of the gut microflora and diet-related obesity, linking it to inflammation and impaired energy metabolism. They further note that gut flora composition shifts toward healthier bacteria dominance in obese subjects on dietary restriction for weight loss.

Ly et al. wrap up with a discussion of the equivocal findings from studies employing probiotics as prevention or mitigation of atopic diseases and a short note on the requirement of vitamin D for healthy gut microbial effects on inflammation. They conclude stating that evidence suggests early diversity of microbiota is pivotal to healthy gut-immune dynamics and that future research must comprise data on maternal flora-neonate flora interactions, vitamin D’s role and dietary confounders.

Have a comment? Tell us what you think. Please feel free to post your own comments and/or predictions below.


  1. Taking probiotics will have a vastly positive impact on your digestive health. They’re great for overcoming problems like diarrhea and constipation. Probiotics will also reduce gas and flatulence.

  2. Most people recognize the immunity boosting benefits of probiotics. The beneficial bacteria, however, can be used to accomplish a wide range of additional health goals.

    Recent research suggests that probiotics could be particularly beneficial for overweight or obese individuals, including the ones suffering from type 2 diabetes.