2017 Top Stories in Gastroenterology: Gut Microbiomes
My selection for top story of the year is “Prebiotics Reduce Body Fat and Alter Intestinal Microbiota in Children Who Are Overweight or With Obesity,” by Nicolucci and colleagues.1 This work was published in Gastroenterology, the premiere journal of the American Gastroenterological Association. The rapid pace of enhancement of our understanding of the role of the gut microbiome in health and disease is staggering. It is becoming increasingly clear that specific alterations in our diets can have a major impact on promoting health and preventing disease. This paper addresses the potential role of diet, specifically the prebiotic oligofructose-enriched inulin (OI), in altering body composition of overweight or obese children. At the end of just 16 weeks, those receiving OI had a decrease in body fat, whereas children receiving placebo had a slight increase. Ingestion of OI altered composition of the gut microbiota, which is likely responsible for the changes in body composition.
Several studies now show significant health benefits from the ingestion of prebiotics, including enhanced survival of those with colorectal cancer by increased consumption of dietary fiber.2 As healthcare providers, it behooves us to stay abreast of the developments regarding diet and health or disease prevention. The inclusion of altered dietary habits in our recommendations to patients is refreshing in the current era of medication-focused care.
Dr. Geoffrey Preidis, Department of Pediatrics, Baylor College of Medicine, provided a commentary on the Nicolucci paper, when it was initially published. It is reprinted here for your convenience:
Overnutrition and obesity are among the most pressing health problems afflicting children today. Interventions that attempt to normalize growth trajectories have demonstrated limited success, leaving overnourished children at risk of becoming overnourished adults and developing an array of comorbidities that include diabetes, dyslipidemia, steatosis, and cardiovascular diseases. Preclinical studies provide compelling evidence that the gut microbiome contributes to the regulation of body weight, although mechanisms underlying this contribution are poorly understood. A recent study by Nicolucci and colleagues in Gastroenterology begins to explore how body composition in childhood may be influenced by prebiotics—non-digestible dietary components that benefit the host by modulating the intestinal microbiota.
In a single-center, randomized, double-blind, placebo-controlled trial, overweight/obese but otherwise healthy children ages 7 to 12 years received prebiotic oligofructose-enriched inulin or an isocaloric placebo daily for 16 weeks. Body weight increased in both groups; however, prebiotics conferred a smaller magnitude of weight gain with more favorable body weight z-scores, BMI, and percent trunk fat compared with placebo. Prebiotics also altered gut microbial community composition, including increased abundance of Bifidobacterium, a genus containing numerous beneficial species, and modestly reduced serum triglycerides and the proinflammatory cytokine IL-6, which are often elevated in obesity. Perhaps most interestingly, prebiotics altered quantities of primary fecal bile acids, which are regulated in part by gut bacteria and could influence weight gain by promoting digestion of dietary fat and activating nuclear receptors and metabolic pathways in multiple organs throughout the body.
These intriguing results are preliminary, given that body composition differed only in terms of relative change from baseline, not in absolute terms between groups at the end of the trial. Furthermore, it is not yet known whether these effects could be generalized to overnourished individuals with comorbidities including diabetes and liver disease, or to children with ethnicities and dietary patterns that differ from those enrolled in this small Canadian cohort. Nonetheless, this study provides promising evidence that a defined prebiotic intervention can influence microbiota-dependent factors associated with body composition changes. A more complete understanding of mechanisms underlying these associations might one day enable custom prebiotic regimens to meet the specific metabolic needs of an overnourished individual.
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Additional Info
- Song M, Wu K, Meyerhardt JA, et al. Fiber intake and survival after colorectal cancer diagnosis [published online November 2, 2017]. JAMA Oncol. doi: 10.1001/jamaoncol.2017.3684.
- Nicolucci AC, Hume MP, Martínez I, et al. Prebiotics Reduce Body Fat and Alter Intestinal Microbiota in Children Who Are Overweight or With Obesity. Gastroenterology. 2017;153(3):711-722.
Disclosure statements are available on the authors' profiles: