Effect of Drinks Containing Fruit Polyphenol Extracts and Fibre on Postprandial Glycaemia. (Glu-MIX)
Effect of Drinks Containing Fruit Polyphenol Extracts and Fibre on Postprandial Glycaemia. (Glu-MIX)
Postprandial glycaemia refers to the transient rise in blood glucose levels that occurs after
 consuming a meal. Large fluctuations in blood glucose levels, experienced on a frequent
 basis, may impair the functioning of pancreatic beta cells, and thus elevate the risk of
 developing type 2 diabetes mellitus (T2DM) and cardiovascular disease. Our group has
 previously shown that consuming a drink containing fruit polyphenols immediately before a
 meal, may reduce postprandial glycaemia. Importantly, other fruit components, namely soluble
 fibres, also impact on carbohydrate digestion by slowing gastric emptying rates. Combining
 fruit polyphenols and fibre in a drink may, potentially, have additive or synergistic effects
 on reducing postprandial glycaemia.

 This study will investigate the effects of drinks containing blackcurrant polyphenol extract
 combined with pulp (source of fibre), and pulp alone, on postprandial outcomes and cognitive
 function following a mixed carbohydrate (starch and sucrose) test meal.
Intake of carbohydrate-rich foods transiently increases blood glucose levels (known as
 postprandial glycaemia). Repeated, high, postprandial glucose responses are evidenced to
 impair pancreatic beta cell function, thus increasing the risk of developing type-2 diabetes
 mellitus and cardiovascular disease. Therefore, meals that elicit a reduced, or more gradual,
 rise in blood glucose levels are desirable.

 Previous studies have shown that consuming a drink containing fruit polyphenols, such as
 those from blackcurrants (BC), immediately before a high carbohydrate meal, reduced the
 postprandial glycaemic response. Importantly, other fruit components, namely soluble fibres,
 also impact on carbohydrate digestion by slowing gastric emptying rates. It is not yet known
 the effect of combining fibre and polyphenols on postprandial glycaemia. Although limited,
 there is a growing body of evidence showing beneficial acute effects of polyphenols in
 cognitive function which is of great interest in many work and academic environments where
 fast cognitive enhancement is wanted to perform a task or an exam.

 This study will investigate the effects of drinks containing BC polyphenol extract combined
 with pulp (source of fibre), and pulp alone, on postprandial outcomes and cognitive function
 following a mixed carbohydrate (starch and sucrose) test meal.

 Study design: A randomised, controlled, double-blind, cross-over study, of the healthy adult
 UK population, will be conducted. All subjects will receive the placebo drink, pulp only
 drink and the pulp with polyphenol drink in a random order. Baseline (fasted) blood samples
 will be taken before consuming the test drink (T0 min). Immediately following consumption of
 the drink, a mixed carbohydrate test meal will be consumed. Further blood samples will be
 collected at regular times until T150 min. Blood samples will be analysed for plasma glucose,
 insulin, glucose-dependent insulinotropic peptide (GIP) and C-peptide. Subjects will also
 perform a 30 min computer based cognitive performance test at baseline (T-45 min) and
 endpoint (T165 min). Visual analogue scales will be used to assess the effect of the test
 drinks on a range of sensory characteristics e.g. palatability, satiety and subjective mood
 feelings. Finally, an ad libitum pasta meal at the end of the study visit (T 215 min) will be
 used to assess the effects on energy intake.
Inclusion Criteria:

 -  Age: 18-70 years

 -  Men and women

 -  Healthy (free of diagnosed diseases listed in the exclusion criteria)

 -  Body Mass Index 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 breastfeeding

 -  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.

 -  Full Blood Counts and Liver Function test results outside of the normal range.

 -  Current smokers, or reported giving up smoking within the last 6 months

 -  History of substance abuse or alcoholism

 -  Reported history of Cardiovascular disease, 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/ high fibre foods for
 48 h before the study

 -  Weight change >3 kg in preceding 2 months

 -  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: alpha-glucosidase inhibitors (acarbose:
 Glucobay), insulin sensitizing drugs (metformin: Glucophage, Glucophage SR, Eucreas,
 Janumet; thiazolidinediones: Actos, Competact), sulfonylureas (Daonil, Diamicron,
 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: higher dose
 vitamins/minerals (>200% Recommend Nutrient Intake), 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.