Mulberry-Extract Improves Glucose Tolerance and Decreases Insulin Concentrations in Normoglycaemic Adults: Results of a Randomised Double-Blind Placebo-Controlled Study

Talk Code: 
EP2E.08
Presenter: 
Mark Lown
Co-authors: 
Richard Fuller, Helen Lightowler, Ann Fraser, Andrew Gallagher, Beth Stuart, Christopher Byrne, George Lewith
Author institutions: 
PCPS University of Southampton, Phynova Group Ltd, Southampton National Institute for Health Research Biomedical Research Centre University Hospital Southampton

Problem

High sugar and refined carbohydrate intake is associated with weight gain, increased incidence of diabetes and is linked with increased cardiovascular mortality. Reducing the health impact of poor quality carbohydrate intake is a public health priority. Reducose®, a proprietary mulberry leaf extract (ME) may reduce blood glucose responses following dietary carbohydrate intake by reducing absorption of glucose from the gut.

Approach

A double-blind, randomised, repeat measure, phase 2 crossover design was used to study the glycaemic and insulinaemic response to one reference product and three test products at the Functional Food Centre, Oxford Brooks University, UK. Participants; 37 adults aged 19-59 years with a BMI ≥ 20kg/m2 and ≤ 30kg/m2. The objective was to determine the effect of three doses of mulberry-extract (Reducose®) versus placebo on blood glucose and insulin responses when co-administered with 50g maltodextrin in normoglycaemic healthy adults. We also evaluated the gastrointestinal tolerability of the mulberry extract.

Findings

Thirty-seven participants completed the study: The difference in the positive Incremental Area Under the Curve (pIAUC) (glucose (mmol / L x h)) for half, normal and double dose ME compared with placebo was -6.1 % (-18.2%, 5.9%; p=0.316), -14.0% (-26.0%, -2.0%; p=0.022) and -22.0% (-33.9%, -10.0%; p<0.001) respectively. The difference in the pIAUC (insulin (mIU / L x h)) for half, normal and double dose ME compared with placebo was -9.7% (-25.8%, 6.3%; p=0.234), -23.8% (-39.9%, -7.8%; p=0.004) and -24.7% (-40.8%, -8.6%; p=0.003) respectively. There were no statistically significant differences between any of the 4 groups in the odds of experiencing one or more gastrointestinal symptoms (nausea, abdominal cramping, distension or flatulence).

Consequences

Mulberry leaf extract significantly reduces total blood glucose rise after ingestion of maltodextrin over 120 minutes. The pattern of effect demonstrates a classical dose response curve with significant effects over placebo. Importantly, total insulin rises were also significantly suppressed over the same time-period. There were no statistically significant differences between any of the treatment groups (including placebo) in the odds of experiencing one or more gastrointestinal symptoms. Mulberry extract may have multiple modes of action and further studies are necessary to evaluate ME as a potential target for the prevention of type 2 diabetes and the regulation of dysglycaemia.

Submitted by: 
Mark Lown
Funding acknowledgement: 
Technology Strategy Board / Innovate UK Grant