Effects of Fruit Extracts on Glycaemia: The GLU-FRU Study
Condition: Postprandial Hyperglycemia
MeSH terms: Hyperglycemia
Study type: Interventional

Summary: 
      Raised blood glucose levels can lead to adverse modifications to functional proteins within
      the body and eventually lead to the development of type 2 diabetes. Fruit polyphenols may
      help to control glycaemia following a carbohydrate meal or beverage. The aim of this study is
      to investigate the effects of blackcurrant (BC) and apple (A) extracts on postprandial
      glycaemia, insulinaemia and plasma gastric inhibitory polypeptide concentrations following a
      mixed carbohydrate test meal.
    

Detailed description: 
      Introduction:

      Diets with a high glycaemic load (a measure of the overall blood glucose-raising effect of a
      serving of a food) and containing high amounts of non-milk extrinsic sugars may contribute
      towards increased risk of developing type 2 diabetes (T2D). Raised blood glucose levels can
      lead to adverse modifications to functional proteins within the body and eventually lead to
      the development of T2D. Large peaks in blood glucose after a meal are a risk factor for T2D,
      and therefore it is desirable to consume a diet that will allow more gradual rises in blood
      glucose levels after meals. Fruit polyphenols may help to control glycaemia following a
      carbohydrate meal or beverage. Possible mechanisms include inhibition of intestinal enzymes
      and inhibition of intestinal glucose absorption by decreasing SGLT1/GLUT2 transport activity.
      The scientific literature also suggests that foods rich in polyphenols exert beneficial
      effects on risk factors of cardiovascular disease such as hypertension, lipid metabolism and
      vascular function.

      Study Design:

      A randomised, controlled, double-blind, cross-over study will be conducted. Subjects will
      receive combined blackcurrant and apple polyphenols, apple polyphenols only or placebo in
      random order at 3 separate study visits immediately before a high-carbohydrate meal. Seven
      days wash-out period will be required between study days.Standardised diet and exercise
      advice will be given prior to the visit. Subjects will arrive on each study visit between
      09.00 and 10.00 h, after a 12 h overnight fast. They will then be cannulated in a forearm
      vein and baseline fasting blood samples will be taken in duplicate. All test drinks will be
      blended to be equal in volume, macronutrient and energy content. Fruit extracts instead of
      whole fruits will be administered to avoid the confounding effect of fruit fibre/viscosity on
      gastric emptying rate. Following consumption of the test drink, the high carbohydrate meal
      (starch and sucrose) will be served (white bread with apricot jam). Outcome variables will be
      measured postprandially until 120 min post-meal.
    

Intervention name(s): Polyphenols
Intervention type(s): Dietary Supplement
Intervention description(s): Drinks will be delivered in random order at 3 separate study visits immediately before a high-carbohydrate meal. Seven days wash-out period will be required between study days.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: Polyphenol; Fruit; Metabolic