Weight, habitual fibre intake, and microbiome composition predict tolerance to fructan supplementation.

Fructans are commonly used as dietary fibre supplements for their ability to promote the growth of beneficial gut microbes. However, fructan consumption has been associated with various dosage-dependent side effects. We characterised side effects in an exploratory analysis of a randomised trial in healthy adults (n = 40) who consumed 18 g/day inulin or placebo. We found that individuals weighing more or habitually consuming higher fibre exhibited the best tolerance. Furthermore, we identified associations between gut microbiome composition and host tolerance. Specifically, higher levels of Christensenellaceae R-7 group were associated with gastrointestinal discomfort, and a machine-learning-based approach successfully predicted high levels of flatulence, with [Ruminococcus] torques group and (Oscillospiraceae) UCG-002 sp. identified as key predictive taxa. These data reveal trends that can help guide personalised recommendations for initial inulin dosage. Our results support prior ecological findings indicating that fibre supplementation has the greatest impact on individuals whose baseline fibre intake is lowest.

Interplay between particle size and microbial ecology in the gut microbiome.

Physical particles can serve as critical abiotic factors that structure the ecology of microbial communities. For non-human vertebrate gut microbiomes, fecal particle size (FPS) has been known to be shaped by chewing efficiency and diet. However, little is known about what drives FPS in the human gut. Here, we analyzed FPS by laser diffraction across a total of 76 individuals and found FPS to be strongly individualized. Surprisingly, a behavioral intervention with 41 volunteers designed to increase chewing efficiency did not impact FPS. Dietary patterns could also not be associated with FPS. Instead, we found evidence that mammalian and human gut microbiomes shaped FPS. Fecal samples from germ-free and antibiotic-treated mice exhibited increased FPS relative to colonized mice. In humans, markers of longer transit time were correlated with smaller FPS. Gut microbiota diversity and composition were also associated with FPS. Finally, ex vivo culture experiments using human fecal microbiota from distinct donors showed that differences in microbiota community composition can drive variation in particle size. Together, our results support an ecological model in which the human gut microbiome plays a key role in reducing the size of food particles during digestion, and that the microbiomes of individuals vary in this capacity. These new insights also suggest FPS in humans to be governed by processes beyond those found in other mammals and emphasize the importance of gut microbiota in shaping their own abiotic environment.

A Randomized Trial of Inspiratory Training in Children and Adolescents With Obesity.

Introduction: Children with obesity suffer excess dyspnea that contributes to sedentariness. Developing innovative strategies to increase exercise tolerance and participation in children with obesity is a high priority. Because inspiratory training (IT) has reduced dyspnea, we sought to assess IT in children with obesity. Methods: We conducted a 6-week randomized IT trial involving 8- to 17-year-olds with obesity. Participants were randomized 1:1 to either high [75% of maximal inspiratory pressure (MIP)] or low resistance control (15% of MIP) three times weekly. Assessments included adherence, patient satisfaction, and changes in inspiratory strength and endurance, dyspnea scores and total activity level. Results: Among 27 randomized, 24 (89%) completed the intervention. Total session adherence was 72% which did not differ between treatment groups. IT was safe, and more than 90% felt IT benefitted breathing and general health. IT led to a mean improvement (95% CI) in inspiratory strength measured by MIP of 10.0 cm H2O (-3.5, 23.6; paired t-test, p = 0.139) and inspiratory endurance of 8.9 (1.0, 16.8; paired t-test, p = 0.028); however, there was no significant difference between high- and low-treatment groups. IT led to significant reductions in dyspnea with daily activity (p < 0.001) and in prospectively reported dyspnea during exercise (p = 0.024). Among the high- versus low-treatment group, we noted a trend for reduced dyspnea with daily activity (p = 0.071) and increased daily steps (865 vs. -51, p = 0.079). Discussion: IT is safe and feasible for children with obesity and holds promise for reducing dyspnea and improving healthy activity in children with obesity. Breathe-Fit trial NCT05412134.