Wheat bran with RPS boosts serum SCFAs in obese people without improving health parameters

Consumption of wheat bran (WB) with reduced particle size (RPS) increases concentrations of fasting serum short-chain fatty acid (SCFA) in obese individuals, a study has shown. Such changes, however, do not appear to have beneficial effects on health parameters.

Thirty-six normal-weight and 14 obese participants consumed 20-g WB RPS or placebo (maltodextrin) over 1 month. The authors measured fasting serum and faecal SCFAs, faecal metabolite profiles, and microbiota composition as fermentation parameters before and after the intervention.

They also measured faecal output, faecal dry weight, fat excretion, transit, stool consistency, intestinal permeability, and serum total cholesterol, triglyceride, and C-reactive protein concentrations as health parameters. The effect of WB RPS on fermentation of other carbohydrates was assessed by quantifying postprandial cumulative serum ¹³C-SCFA after a challenge with ¹³C-inulin.

WB RPS consumption led to higher fasting serum acetate (p<0.05) and total SCFA (p<0.05) concentrations in obese participants. Fasting serum propionate concentrations were lower in obese than normal-weight participants at baseline (0.89±0.52 1.57±0.75 µmol/L; p<0.01), but not after WB RPS (1.35±0.63 vs 1.75±0.77 µmol/L; p=not significant).

WB RPS neither improved colonic fermentation of ¹³C-inulin nor affected microbiota composition. Notably, the intervention did not have a beneficial impact on health parameters either in normal-weight or obese participants.

“WB has been associated with improved gastrointestinal health and a reduced risk of metabolic disorders,” the authors said. “Reducing the particle size of WB might increase its fermentability and facilitate cross-feeding between the gut bacteria and in this way produce health effects.”