Gut microbiota, probiotics, and vitamin D: Interrelated exposures influencing allergy, asthma, and obesity?
Journal of Allergy and Clinical Immunology; Clinical reviews in allergy and immunology
Ngoc P. Ly MD, MPHa lyn at peds.ucsf.edu, Augusto Litonjua MD, MPHb, Diane R. Gold MD, MPHb and Juan C. Celedón MD, DrPHc
a Division of Pediatric Pulmonary Medicine, Department of Pediatrics, University of California San Francisco, Calif
b Channing Laboratory, Brigham and Women’s Hospital and Harvard Medical School, Boston, Mass
c Division of Pediatric Pulmonary Medicine, Allergy and Immunology, Children’s Hospital of Pittsburgh of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pa
Received 7 December 2010; revised 3 February 2011; accepted 3 February 2011. Available online 21 March 2011.
Current evidence supports a role for gut colonization in promoting and maintaining a balanced immune response in early life. An altered or less diverse gut microbiota composition has been associated with atopic diseases, obesity, or both. Moreover, certain gut microbial strains have been shown to inhibit or attenuate immune responses associated with chronic inflammation in experimental models. However, there has been no fully adequate longitudinal study of the relation between the neonatal gut microbiota and the development of allergic diseases (eg, atopic asthma) and obesity. The emergence of promising experimental studies has led to several clinical trials of probiotics (live bacteria given orally that allow for intestinal colonization) in human subjects.
Probiotic trials thus far have failed to show a consistent preventive or therapeutic effect on asthma or obesity. Previous trials of probiotics have been limited by small sample size, short duration of follow-up, or lack of state-of-the art analyses of the gut microbiota. Finally, there is emerging evidence that the vitamin D pathway might be important in gut homeostasis and in signaling between the microbiota and the host. Given the complexity of the gut micriobiota, additional research is needed before we can confidently establish whether its manipulation in early life can prevent or treat asthma, obesity, or both.