Effects of Carbohydrase-inhibiting Polyphenols on Glycaemic Response in Vivo
Consumption of carbohydrate containing foods or sugary drinks brings about changes to the blood glucose levels. After a meal or drink, blood glucose levels rise until it reaches a peak concentration usually after 30 minutes. When the body senses the increase in blood glucose, a hormonal process involving insulin takes place to ensure that the glucose is taken up from the blood for storage and where it is needed for energy in the body. This process then brings about a decrease in the concentration of glucose until it reaches approximately the starting concentration. The original concentration of glucose is attained approximately 2 hours after eating or drinking a carbohydrate food or sugary drink respectively.
Different carbohydrates and sugary drinks have different effects on blood glucose response depending on the amount as well as the type of carbohydrate. Those that give rise to a high glucose response compared to a reference carbohydrate (usually glucose) are said to be high glycaemic index (GI) foods and those with a lower glucose response compared to a reference carbohydrate (usually glucose) are said to be low glycaemic index (GI) foods.(1)
Research has shown that diets that give rise to a high glucose response are associated with a number of abnormalities like increased metabolic syndrome (2). Metabolic syndrome mostly comprises of insulin resistance and glucose intolerance which gives an increased risk of type 2 diabetes. (3) It also gives rise to other conditions like high blood pressure (arterial hypertension), elevated blood insulin levels (hyper-insulinemia), elevated amounts of fat in the liver (fatty hepatosis) and elevated amounts of lipids in the blood (dyslipidemia). After type 2 diabetes become clinically apparent, the risk of cardiovascular disease also rises. (4) Research has also shown that foods/drinks which raise blood glucose levels gradually (low GI) rather than rapidly (high GI) have health benefits which include reducing the risk of metabolic syndrome (5). In vitro studies have shown that polyphenols found in fruits, vegetables and plant based foods have a positive effect on carbohydrate metabolism and can lower the blood glucose levels. (6)
This research will determine whether the presence of polyphenols in the diet has any lowering effect on the blood glucose levels and hence the glycaemic index of foods. This will be determined by asking volunteers to consume polyphenol rich drink/food together with white bread and determine the glycaemic response. The GI of bread will be determined initially as a reference.
Analysis will be done by measuring blood glucose response to white bread alone as reference and then to white bread with test sample containing polyphenols and then determine GI and see how the GI of bread will be affected. Other analyses to be done are plasma insulin, glucagon, gastric inhibitory polypeptide (GIP) and glucagon like peptides-1 (GLP-1) as they all relate to glycaemic response.
Study hypothesis is that glucose metabolism will be affected.
- Only healthy participants undertook the study (Hence metabolic syndrome participants not part of the study)
- Only glucose and insulin were analysed in the plasma (hence GIP, GLP-1 and glucagon not part of end points)
|Hyperglycaemia||Other: Reference food Other: Test food dose 1 Other: Test food dose 2|
|Study Design:||Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single (Outcomes Assessor)
Primary Purpose: Basic Science
|Official Title:||Effects of Carbohydrase-inhibiting Polyphenols on Glycaemic Response in Vivo|
- Changes in Incremental Area Under the Curve for glucose and insulin [ Time Frame: Blood will be collected at different time points within 3 hours, twice a week, for two weeks per volunteer ]
|Study Start Date:||August 2014|
|Study Completion Date:||September 2015|
|Primary Completion Date:||March 2015 (Final data collection date for primary outcome measure)|
Active Comparator: Reference food
The reference food is white bread
Other: Reference food
Reference food will be used to which test food samples will be compared to.
Experimental: Test food dose 1
Test food dose 1 response will be compared to reference test food
Other: Test food dose 1
Will contain low dose of a mixture of polyphenols in addition to the reference food
Experimental: Test food dose 2
Test food dose 2 response will be compared to reference test food as well as to test food dose 1
Other: Test food dose 2
Will contain high dose (twice of the low dose) of a mixture of polyphenols in addition to the reference food
Show Detailed Description
Please refer to this study by its ClinicalTrials.gov identifier: NCT01994135
|School of Food Science and Nutrition|
|Leeds, West Yorkshire, United Kingdom, LS2 9JT|
|Study Chair:||Gary Williamson||University of Leeds|
|Principal Investigator:||Hilda Nyambe||University of Leeds|