Acute Study of Anthocyanin-rich Bilberry and Polyphenol-rich Apple Extracts on Postprandial Glycaemic Response

Strategies to control chronic postprandial hyperglycaemia by optimizing the functionality of foods would strengthen efforts to reduce the risk of developing T2D in the general population. Polyphenolic constituents, may help to delay starch and disaccharide digestion and glucose absorption following a carbohydrate-containing meal or beverage. In vitro studies suggest that some berry anthocyanins and apple polyphenols are effective inhibitors of digestive enzymes, α-amylases and α-glucosidases. Furthermore, polyphenols found in berries and apples inhibit the action of intestinal glucose transporters. Human data is limited; however, randomized controlled trials (RCTs) have shown that berries and apple products reduced postprandial glucose concentrations following consumption of either starch, glucose or sucrose loads. The aim of this study is to test the hypothesis that consumption of a fruit bar containing anthocyanin-rich bilberry and polyphenol-rich apple extracts together with a starch and sucrose meal would reduce the postprandial glycemic response. This study is a randomized cross over study and will aim to recruit 24 overweight (BMI \> 25.0), men or post-menopausal women, aged ≥40 and ≤ 70 years who will attend four study sessions. The first study session will be an oral glucose tolerance test (OGTT) and the remaining three will be identical in all respects except for the composition of the fruit bar. Consecutive blood samples will be collected in all 4 study sessions which will be used to measure glucose, insulin, C-peptide, incretins and lipids.