Effects of a Fiber Mixture on Gut Microbiome Diversity and Short-Chain Fatty Acids in Adults with Increased Metabolic Risk: A Randomized Cross-over Study

This randomized, double-blind, cross-over study included 65 healthy subjects, aged 45–70 years, with increased metabolic risk (i.e., body mass index [BMI] 25–30 kg/m2, low to moderate daily dietary fibre intake, <30g/day). Subjects took daily a fibre mixture of Acacia gum and carrot powder or placebo for 12 weeks, with an 8-week wash-out period. Faecal samples for measurement of SCFAs and microbiome analysis were collected every 4 weeks. The fibre mixture exerted microbiome modulation, with an increase in ß-diversity (p < 0.001). a-diversity was lower during fibre mixture intake compared to placebo after 4, 8 and 12 weeks (p = 0.002; p = 0.012; p = 0.031). Faecal samples taken at baseline of the intervention period were used for culturing experiments in which the microbiome modulating effects of fiber exposure in vitro were determined.