Effects of Fruit Extracts on Glycaemia: The GLU-FRU Study

Inclusion Criteria: * Age: 20-60 y * Male and female (post-menopausal only) * Healthy (free of diagnosed diseases in the exclusion criteria) * BMI 18-35 kg/m2 * Able to understand the information sheet and willing to comply with study protocol * Able to give informed written consent Exclusion Criteria: * Those diagnosed with Phenylketonuria (PKU), * Those with known or suspected food intolerances, allergies or hypersensitivity * Women who are known to be pregnant or who are intending to become pregnant over the course of the study * Women who are breast feeding * Participation in another clinical trial * Those who have donated blood within 3 months of the screening visit and participants for whom participation in this study would result in having donated more than 1500 millilitres of blood in the previous 12 months. * Those with Full Blood Counts and Liver Function test results outside of the normal range (see table 1 below). * Pre-menopausal women due to the potential influence of cyclical changes in reproductive hormones on insulin sensitivity * Current smokers, or reported giving up smoking within the last 6 months * History of substance abuse or alcoholism * Reported history of CVD, diabetes (or fasting glucose ≥ 7.1 mmol/L), cancer, kidney, liver or bowel disease, gastrointestinal disorder or use of drug likely to alter gastrointestinal function * Unwilling to restrict consumption of specified high polyphenol foods for 24 h before the study * Weight loss \>3kg in preceding 2 months and body mass index \<18 or \>35 kg/m2 * Blood pressure ≥160/100 mmHg * Total cholesterol ≥ 7.5 mmol/L; fasting triacylglycerol concentrations ≥ 5.0 mmol/L * Medications that may interfere with the study such as alpha-glucosidase inhibitors (acarbose: Glucobay), insulin-sensitising drugs (metformin: Glucophage, Glucophage SR, Eucreas, Janumet; thiazolidinediones: Actos, Competact), sulfonylureas (Daonil, Diamicron MR, Glibenese, Minodiab, Amaryl Tolbutamide), and lipid-lowering drugs (statins, nicotinic acid, colestyramine anhydrous, ezetimibe, fibrates). Other medications should be reviewed by medical representative from KCL on a case by case basis. * Nutritional supplements that may interfere with the study such as higher dose vitamins/minerals (\>200% RNI), B vitamins, Vitamin C, calcium, copper, chromium, iodine, iron, magnesium, manganese, phosphorus, potassium and zinc. Subjects already taking vitamin or minerals at a dose around 100% or less up to 200% of the RNI, or evening primrose/algal/fish oil supplements will be asked to maintain habitual intake patterns, ensuring that they take them every day and not sporadically. They will be advised not to stop taking supplements or start taking new supplements during the course of the study.