Effect of mulberry fruit extract on glucose fluxes after a wheat porridge meal: a dual isotope study in healthy human subjects.

BACKGROUND

Previous research has shown the efficacy of mulberry extracts for lowering post-prandial glucose (PPG) responses. The postulated mechanism is slowing of glucose absorption, but effects on glucose disposal or endogenous production are also possible. This research assessed the effect of a specified mulberry fruit extract (MFE) on these three glucose flux parameters.

METHODS

The study used a double-blind, randomized, controlled, full cross-over design. In 3 counter-balanced treatments, 12 healthy adult male subjects, mean (SD) age 24.9 (2.50) years and body mass index 22.5 (1.57) kg/m, consumed porridge prepared from C-labelled wheat, with or without addition of 0.75 g MFE, or a solution of C-glucose in water. A co-administered H-glucose venous infusion allowed for assessment of glucose disposal. Glucose flux parameters, cumulative absorption (time to 50% absorption, T), and PPG positive incremental area under the curve from 0 to 120 min (+iAUC) were determined from total and isotopically labelled glucose in plasma. As this exploratory study was not powered for formal inferential statistical tests, results are reported as the mean percent difference (or minutes for T) between treatments with 95% CI.

RESULTS

MFE increased mean T by 10.2 min, (95% CI 3.9-16.5 min), and reduced mean 2 h post-meal rate of glucose appearance by 8.4% (95% CI -14.9 to -1.4%) and PPG + iAUC by 11% (95% CI -26.3 to -7.3%), with no significant changes in glucose disposal or endogenous production.

CONCLUSIONS

The PPG-lowering effect of MFE is primarily mediated by a reduced rate of glucose uptake.