Background: There is recent evidence that glucose delivered to the distal small intestine (SI) may stimulate the ileal brake and inhibit appetite. High polyphenolic grape extract (PGE) has been shown to inhibit α-amylase and α-glucosidase activity, two key enzymes required for starch digestion, in vitro. It is hypothesised to slow digestion and absorption of starch in the proximal SI such that glucose may be delivered distally into the ileum and suppress appetite. This study investigated the safety and efficacy of a PGE supplement, delivered within a capsule and consumed with a high-starch breakfast, on appetite ratings and ad libitum energy intake (EI) at a subsequent lunch meal.
Methods: Twenty healthy, non-obese (BMI 18-28 kg/m(2)) male volunteers participated in a randomised, double blind, placebo controlled, three arm, cross-over study. Participants were administered (i) low dose PGE500 (500 mg), (ii) high dose PGE1500 (1500 mg), and (iii) matched placebo with a 2 MJ high-starch breakfast (white bread); followed 3 h later by a single item buffet-style lunch meal (pasta and meat sauce). Outcome variables were feelings of hunger, fullness, prospective thoughts of food (TOF) and satisfaction assessed using visual analogue scales (VAS); and ad lib energy and macronutrient intake at the lunch meal.
Results: There was no detectable effect of PGE500 or PGE1500 compared with placebo (all, time*supplement interaction, P > 0.05) on VAS-assessed hunger, fullness, TOF or satisfaction. There was also no evidence that PGE significantly altered ad lib energy or macronutrient intake at the lunch meal relative to placebo (P > 0.05). EI following PGE500 was +164 kJ higher than placebo (+5.3%, P > 0.05); and EI following PGE1500 was -51 kJ lower than placebo (-1.7%, P > 0.05).
Conclusions: Whilst well tolerated, there was no evidence that encapsulated low dose PGE500 or high dose PGE1500 consumed with a high starch breakfast meal altered postprandial hunger, fullness, TOF or satisfaction relative to a matched placebo. Nor was there evidence that either dose altered ad lib energy or macronutrient intake at an outcome meal.
Trial registration: ACTRN12614000041651.