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

Not Applicable

Completed

Interventions: Dietary Supplement: GCE + Low ALA
Dietary Supplement: Placebo
Dietary Supplement: GCE + High ALA

Brief Summary: 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: 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.

Recruitment & Eligibility

Inclusion Criteria

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

Arm && Interventions

Group	Intervention	Description
GCE + Low ALA	GCE + Low ALA	Green coffee extract and a low dose of alpha-lipoic acid prior to an oral glucose tolerance test
Placebo	Placebo	Inert placebo pill prior to an oral glucose tolerance test
GCE + High ALA	GCE + High ALA	Green coffee extract and a moderate dose of alpha-lipoic acid prior to an oral glucose tolerance test

Primary Outcome Measures

Name	Time	Method
Glucose incremental area under the curve	2 hours	glucose incremental area under the curve measured during an oral glucose tolerance test

Secondary Outcome Measures

Name	Time	Method
Mean glucose concentration	2 hours	Mean glucose concentration measured during an oral glucose tolerance test
Insulin incremental area under the curve	2 hours	insulin incremental area under the curve measured during an oral glucose tolerance test
Mean insulin concentration	2 hours	mean insulin concentration measured during an oral glucose tolerance test
Postprandial glucose oxidation	2 hours	Postprandial glucose oxidation measured with a metabolic tracer
peak glucose concentration	2 hours	peak glucose concentration measured during an oral glucose tolerance test
peak insulin concentration	2 hours	peak insulin concentration measured during an oral glucose tolerance test
Appetite perceptions	2 hours	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.
Insulin sensitivity	2 hours	insulin sensitivity measured via the Matsuda Index during an oral glucose tolerance test

Locations (1): Goldring Centre for High Performance Sport
🇨🇦
Toronto, Ontario, Canada