British Journal of Nutrition

Review Article

The nutraceutical role of the Phaseolus vulgaris α-amylase inhibitor

Wokadala Cuthbert Obiroa1, Tao Zhanga1 and Bo Jianga1 c1

a1 State Key Laboratory of Food Science and Technology, Southern Yangtze University, 1800 Lihu Avenue, Wuxi, Jiangsu 214122, China


The present review assesses the potential of the Phaseolus vulgaris α-amylase inhibitor isoform 1 (α-AI1) starch blockers as a widely used remedy against obesity and diabetes. Consumption of the α-amylase inhibitor causes marginal intraluminal α-amylase activity facilitated by the inhibitor's appropriate structural, physico-chemical and functional properties. As a result there is decreased postprandial plasma hyperglycaemia and insulin levels, increased resistance of starch to digestion and increased activity of colorectal bacteria. The efficacy and safety of the amylase inhibitor extracts, however, depend on the processing and extraction techniques used. The extracts are potential ingredients in foods for increased carbohydrate tolerance in diabetics, decreased energy intake for reducing obesity and for increased resistant starch. Research developments in the distribution and biosynthesis of the α-amylase inhibitor, relevant physico-chemical properties, the molecular starch-blocking mechanism, anti-obesity and anti-diabetes effects, safety of extracts and the need for research into their potential anti-colorectal cancer effect are discussed.

(Received May 14 2007)

(Revised September 28 2007)

(Accepted October 27 2007)

(Online publication March 11 2008)


c1 Corresponding author: Dr Bo Jiang, fax +86 510 85809610, email


Abbreviations: α-AI1, α-amylase inhibitor isoform 1; α-AI2, α-amylase inhibitor isoform 2; α-AIL, α-amylase inhibitor like; PHA, phytohaemagglutinin; PPA, porcine pancreatic amylase