Mulberry-extract improves glucose tolerance and decreases insulin concentrations in normoglycaemic adults: Results of a randomised double-blind placebo-controlled study.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 28225835 · doi:10.1371/journal.pone.0172239
What was done
A double-blind, randomized, repeated-measures, phase 2 crossover trial was conducted in 37 healthy normoglycaemic adults (aged 19–59 years, BMI 20–30 kg/m²) in the UK. Participants ingested 50 g maltodextrin co-administered with placebo or one of three doses (half, normal, double dose) of a proprietary mulberry leaf extract (Reducose). The primary outcomes were 120-minute positive Incremental Area Under the Curve (pIAUC) for blood glucose and insulin, alongside gastrointestinal tolerability.
What was found
Compared with placebo, mulberry extract reduced glucose pIAUC by -6.1% (-18.2% to 5.9%; p = 0.316) for half dose, -14.0% (-26.0% to -2.0%; p = 0.022) for normal dose, and -22.0% (-33.9% to -10.0%; p < 0.001) for double dose. Insulin pIAUC was reduced compared with placebo by -9.7% (-25.8% to 6.3%; p = 0.234) for half dose, -23.8% (-39.9% to -7.8%; p = 0.004) for normal dose, and -24.7% (-40.8% to -8.6%; p = 0.003) for double dose. There were no statistically significant differences between any groups in the odds of experiencing gastrointestinal symptoms.
Why it matters
Mulberry leaf extract dose-dependently attenuates acute postprandial glucose and insulin surges after refined carbohydrate ingestion in healthy individuals without causing gastrointestinal intolerance.
Limits
The trial had a small sample size (n = 37) and was restricted to healthy normoglycaemic adults, limiting generalizability to populations with dysglycaemia or diabetes. It measured only acute 120-minute responses to isolated maltodextrin rather than mixed meals or long-term clinical endpoints, and exact milligram doses are not stated in the abstract.