Legumes are one of the key components of the traditional Mediterranean diet whose consumption declined with the advancing epidemics of obesity and diabetes in Europe. Among the interesting functional components of Phaseolus vulgaris are alpha-amylase inhibitors and plant lecitins (Phythoemagglutinin, PHA) potentially capable to modulate gut endocrine responses related to food intake and satiety. The purpose of this study was to evaluate the effect of a standardized bean isolate protein (BEANBLOCK?, Indena S.p.A., Milano, Italy) on ghrelin secretion, a stomach-secreted orexigen peptide, and on satiety.

Twelve healthy subjects (BMI: 21.4±1.4 kg/m2, age: 22.5±2.0 years) received in two different occasions, in a randomized cross-over and double-blind design, a standardized meal (40% of their energy expenditure, 999±143Kcal) consisting of a sandwich (white bread, ham, tomato, olive oil) with either 100 mg bean isolate protein or placebo. Circulating ghrelin was measured hourly up to 3h. Satiety was measured every 30 min by VAS (Visual Analogue Scale).

The meal suppressed circulating ghrelin in both studies (p<0.005). After 3h, ghrelin rebounded in the placebo study whereas it was further suppressed with bean isolate protein (+7.7 ± 2.6% vs ­1.4 ± 4.1%, p =0.04). Satiety induced by the meals begun to decrease in 2 hours with placebo (p=0.004), and in 3 hours with bean isolate protein (p=0.001).

Compared to placebo, bean isolate protein suppresses ghrelin secretion to an higher degree and induce a longer duration of satiety suggesting a potential use of this plant derivative for the control of excessive food intake.