BACKGROUND & AIMS
It might be possible to manipulate the intestinal microbiota with prebiotics or other agents to prevent or treat obesity. However, little is known about the ability of prebiotics to specifically modify gut microbiota in children with overweight/obesity or reduce body weight. We performed a randomized controlled trial to study the effects of prebiotics on body composition, markers of inflammation, bile acids in fecal samples, and composition of the intestinal microbiota in children with overweight or obesity.
We performed a single-center, double-blind, placebo-controlled, trial of 2 separate cohorts (March 2014 and August 2014) at the University of Calgary in Canada. Participants included children, 7 – 12 years old, with overweight or obesity (>85th percentile of body mass index) but otherwise healthy. Participants were randomly assigned to groups given either oligofructose-enriched inulin (OI, 8 g/day; n=22) or maltodextrin placebo (isocaloric dose, controls; n=20) once daily for 16 weeks. Fat mass and lean mass were measured using dual-energy-x-ray absorptiometry. Height, weight, and waist circumference were measured at baseline and every 4 weeks thereafter. Blood samples were collected at baseline and 16 weeks, and analyzed for lipids, cytokines, lipopolysaccharide, and insulin. Fecal samples were collected at baseline and 16 weeks; bile acids were profiled using high-performance liquid chromatography and the composition of the microbiota was analyzed by 16S rRNA sequencing and quantitative PCR. The primary outcome was change in percent body fat from baseline to 16 weeks.
After 16 weeks, children who consumed OI had significant decreases in body weight z-score (decrease of 3.1%), percent body fat (decrease of 2.4%), and percent trunk fat (decrease of 3.8%) compared to children given placebo (increase of 0.5%, increase of 0.05%, and decrease of 0.3%, respectively). Children who consumed OI also had a significant reduction in level of interleukin 6 (IL6) from baseline (decrease of 15%) compared with the placebo group (increase in 25%). There was a significant decrease in serum triglycerides (decrease of 19%) in the OI group. Quantitative PCR showed a significant increase in Bifidobacterium spp. in the OI group compared with controls. 16S rRNA sequencing revealed significant increases in species of the genus Bifidobacterium and decreases in Bacteroides vulgatus within the group who consumed OI. In fecal samples, levels of primary bile acids increased in the placebo group but not in the OI group over the 16-week study period.
In a placebo-controlled, randomized trial, we found a prebiotic (OI) to selectively alter the intestinal microbiota and significantly reduce body weight z-score, percent body fat, percent trunk fat, and serum level of IL6 in children with overweight or obesity.
This small study of overweight children found that taking a prebiotic (oligofructose-enriched inulin, 8 g daily for 16 weeks) was associated with less weight gain than placebo and resulted in a shift in the microbiome to include more bifidobacteria. Bifidobacteria is established with breastfeeding and is associated with less weight gain (see graphic 1 for the results of the study).
But, before you Google “oligofructose-enriched inulin” for a supplement to recommend to your overweight patients, remember that this is simply a fiber combined with short-chain sugars found in plants. A prebiotic is generally a soluble fiber that bypasses absorption in the upper intestinal track, passing into the colon and providing fuel for bacterial growth and fermentation (gas; see graphic 2).
Foods rich in inulin include whole grains, onions, garlic, leeks, Jerusalem artichoke, and chicory root. Other prebiotic fibers that would likely work include psyllium, ground flax seed, and guar gum. The good news is that, other than gas and bloating, these products are very safe and may promote the establishment of a healthy microbiome at an early age, which may help with weight management as the child grows into an adult.