How to control food intake: the potential role of new β-glucan-enriched foods

Background Obesity is a dramatic social burden that needs urgent intervention. A strategy to afford this chronic disease and to reduce its epidemic expansion is to control individual food intake through appetite regulation. Satiety is regulated by fine mechanisms that include social, psychological and neuroendocrine factors. The characteristics of food such as palatability, energy density, volume, form and nutrient composition as well as hormones secreted by digestive tract play a fundamental role in these fine mechanisms. Among dietary constituents that can modulate appetite and food intake, dietary fibre had documented effects on increasing satiety, thus playing a potential role in the control of energy balance. The evidence about the satiety efficacy of different types of dietary fibre, are not conclusive: results varied with the type of dietary fibre and with administration protocols (i.e. dietary fibre-rich foods vs pure supplements). However viscous dietary fiber were indicated as the most promising and β-glucans from oat and barley, known for their ability to modulate blood lipids, were poorly investigated for this aspect. Aim In this framework the satiety effect of a bread and a beverage containing 3 g of barley β-glucans per portion were evaluated in healthy subjects. Materials and Methods In both cases a powder containing >77.5% barley β-glucan concentrate, namely GlucagelTM (DKSH), was used. The new β-glucans breads (BGBR) and beverages (BGBE) were formulated and prepared in pilot plant and their sensory evaluation was performed and compared to that of relative control foods (without dietary fibre). Among several preparations those having a sensory profile similar to control foods were selected for satiety study. In both cases 14 healthy volunteers were enrolled and two separate protocols for evaluation of appetite sensations and glycaemia and blood hormone concentration in the short-term, respectively, were performed. In protocol 1 the subjects reached the laboratory fasting at 0800 h, they were given a breakfast containing or BGBR or BGBE or respective controls (CBR or CBE) and were asked to report their appetite ratings on 0-100 mm VAS at baseline, 15, 30, 60, 120, 180 min after breakfast. At 180 min they were offered an ad libitum lunch to measure the energy intakes at subsequent meal. In protocol 2, at the same time points subjects were submitted to blood drawings. Results BGBR vs CBR: • reduced hunger and increased fullness and satiety • determined a 19% reduction of energy intake at subsequent lunch • elicited a lower plasma response of ghrelin (hunger hormone) and a higher PYY (satiety hormone) response, independently from insulin response • determined a blunted glucose response. BGBE vs CBE: • increased fullness and satiety perceptions • determined a 18% reduction of energy intake at subsequent lunch (and up to 30% over the 24h) • elicited a higher response of pancreatic polypeptide, independently from insulin response. Conclusions Barley β-glucans, both in solid and liquid foods, by different hormone response, modulate appetite and energy intake in healthy subjects. Long term studies in overweight subjects are needed to evaluate their efficacy for weight management.