Effect of Green Coffee Extract Combined With Alpha-Lipoic Acid on Blood Glucose Homeostasis in Healthy Adults

Study Overview
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Brief Summary
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Green coffee extract (GCE) supplementation has been shown to induce favourable health benefits on glucose metabolism and weight management. Previous literature suggests that the benefits of GCE are due to the high bioavailability of chlorogenic acid (CGA) which is known for its antioxidant and anti-inflammatory properties but is destroyed during the bean roasting process used to make coffee in Western societies. Whilst some studies examining chronic and high dose GCE supplementation (4-12 weeks) report beneficial effects on glucose metabolism and reductions in body mass following supplementation, comparably less is known about the effect of acute (single dose) GCE supplementation. Another natural compound, alpha-lipoic acid (ALA) has antioxidant properties and may also benefit glucose metabolism. The purpose of the current study is to determine the impact of acute supplementation of GCE with ALA on postprandial blood glucose concentration following consumption of a carbohydrate drink in healthy adults. A secondary objective is to evaluate the effect of GCE+ALA on blood insulin concentrations, insulin sensitivity, glucose oxidation, and perceptions of appetite.

Detailed Description
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The primary purpose of this study is to determine if GCE combined with ALA supplementation influences postprandial glucose metabolism. Participants will complete 3 visits to the investigator's laboratory at the University of Toronto. On each occasion, participants will consume a sugary drink (75g sugar) and investigators will take blood and breath samples for 2 hours. Participants will also be asked to fill out some questionnaires about appetite during this time. Thirty minutes before consuming the sugary drink, participants will consume one of the following pill supplements in a randomized order: 1) 200mg CGE + 200mg ALA; 2) 200mg GCE + 400mg ALA; or 3) Placebo (no CGE or ALA). The study will advance knowledge regarding the effects of GCE and ALA on postprandial glycemia and insulin sensitivity.

Official Title
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Effect of Green Coffee Extract Combined With Alpha-Lipoic Acid on Blood Glucose Homeostasis in Healthy Adults

Conditions
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Nutrition, Healthy

Intervention / Treatment
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* Dietary Supplement: GCE + Low ALA
* Dietary Supplement: GCE + High ALA
* Dietary Supplement: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: 18-45 years BMI 20 - 30 kg/m2 Weight stable (within ± 2kg for at least 6 months) Experiencing monthly menstrual periods (eumenorrheic) if female Non-smoker Exclusion Criteria: Previous history of cardiovascular or metabolic disease Use of medication for managing blood glucose or lipid metabolism Current use of monophasic or biphasic oral contraceptives within the last 3 months (triphasic oral contraceptives are okay) Current supplementation of green coffee extract or supplementing in the last 3 months Irregular menstrual cycles (<21 days or >35 days) Pregnant or lactating Recreational smoking of any form (tobacco or cannabis) Not willing to consume the 24-hour control diet prior to metabolic trials

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: GCE + Low ALA<br>Green coffee extract and a low dose of alpha-lipoic acid prior to an oral glucose tolerance test | Dietary Supplement: GCE + Low ALA<br>* Participants will consume a pill containing 200mg green coffee extract and 200mg alpha-lipoic acid 30 minutes before a 75g oral glucose tolerance test<br>|
| Active Comparator: GCE + High ALA<br>Green coffee extract and a moderate dose of alpha-lipoic acid prior to an oral glucose tolerance test | Dietary Supplement: GCE + High ALA<br>* Participants will consume a pill containing 200mg green coffee extract and 400mg alpha-lipoic acid 30 minutes before a 75g oral glucose tolerance test<br>|
| Placebo Comparator: Placebo<br>Inert placebo pill prior to an oral glucose tolerance test | Dietary Supplement: Placebo<br>* Participants will consume a placebo pill (500mg insoluble microcrystalline cellulose, 5mg magnesium stearate, 5mg silicon dioxide) prior to a 75g oral glucose tolerance test<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glucose incremental area under the curve | glucose incremental area under the curve measured during an oral glucose tolerance test | 2 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean glucose concentration | Mean glucose concentration measured during an oral glucose tolerance test | 2 hours | 
| Insulin incremental area under the curve | insulin incremental area under the curve measured during an oral glucose tolerance test | 2 hours | 
| Mean insulin concentration | mean insulin concentration measured during an oral glucose tolerance test | 2 hours | 
| peak glucose concentration | peak glucose concentration measured during an oral glucose tolerance test | 2 hours | 
| peak insulin concentration | peak insulin concentration measured during an oral glucose tolerance test | 2 hours | 
| Postprandial glucose oxidation | Postprandial glucose oxidation measured with a metabolic tracer | 2 hours | 
| Appetite perceptions | Visual analog scales (0-100) will be used to determine perceptions of hunger, satisfaction, fullness, and prospective food consumption with higher scores denoting increased perceptions. | 2 hours | 
| Insulin sensitivity | insulin sensitivity measured via the Matsuda Index during an oral glucose tolerance test | 2 hours |