Study design: A randomised, controlled, double-blind, cross-over study will be conducted. Subjects will consume different drinks at 4 separate study visits. Drinks will contain either: blackcurrant extract (low dose), blackcurrant extract (high dose), citrus extract (low dose), blackcurrant and citrus extract (low dose + low dose), or placebo (no polyphenols). The study will utilise an incomplete block design. Subjects will consume the placebo drink and 3 out of 4 of the polyphenol-containing drinks during the study. At least a 7-day wash-out period will be required between study days. Baseline (fasted) blood samples will be taken in duplicate at T-10 min and T-5 min before consuming the test drink (T+0 min). Immediately following consumption of the drink, a mixed carbohydrate test meal will be consumed. Further blood samples will be collected at 10 min intervals for the first 30 min and then every 15 min until T+90 min and at T+120 min. Blood samples will be analysed for plasma glucose, insulin, glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide 1 (GLP-1), peptide YY (PYY), C-peptide and nonesterified fatty acids (NEFA).