Evaluation of Effects of Green Coffee Bean Extract (GCE) on Physiological and Psychological Variables- a Randomized, Placebo-controlled and Double-blinded Study in Healthy Subjects

Coffee as one of the most favorite worldwide beverages comprises a variety of chemicals maintaining the greatest health benefits among the commonly consumed beverages. Most investigations have so far focused on the beneficial effects of caffeine. On the contrary, knowledge on potential health benefits of non-caffeine coffee compounds is scarce. Coffee contains many polyphenols, especially chlorogenic acids (CGA), which have purported antioxidant abilities. With increasing incidence of degenerative diseases, the general public is turning to use natural herbal supplements, as one of these agents, CGA has been biologically and medically emphasized and can be expected to become a topic addressed in future studies, medical trends and pharmacology. The reducing risk of a variety of diseases following CGA consumption has been mentioned in recent basic and clinical studies. However, there is a lack of studies that examine the behavioral effects of CGA. This study aims to fill this gap.

In a randomized double-blind study, the investigators test the acute effects of coffee enriched with CGA or CGA supplement on physiological functions such as blood pressure, blood glucose, and heart rate, and on psychological functions such as mood and cognitive performance in 30 healthy adult subjects (18-40 years).

Participants will be allocated to an intervention plan using computer-generated random numbers. Treatments comprise of (1) 6g decaffeinated (5 mg caffeine) coffee (250 ml) with high total CGA (560 mg), or (2) 6g decaffeinated coffee (250 ml) with normal total CGA (224 mg) , or (3) 6g decaffeinated coffee (250 ml) with normal total CGA and 800mg green coffee bean extract with total CGA (560mg), or (4) 6g decaffeinated coffee (250 ml) with normal total CGA and placebo, or (5) no treatment group. Participants will be instructed to abstain from alcohol, foods, and beverages containing caffeine, chlorogenic acids and high polyphenol content for 24 hours prior to the experiment. Upon arrival in the laboratory, participants will complete a 24-hour food recall, a psychometric test battery consisting of the questionnaire on competence and control beliefs (FKK), the Life Orientation Test-Revised (LOT-R), the Beliefs about Medicines Questionnaire (BMQ), the Sensitivity to Punishment and Reward Questionnaire (SPSRQ), General Self-Efficacy (SWE) questionnaire, and mood and cognitive performance tests consisting of the Profile of Mood States (POMS) questionnaire, a parametric Go/no-Go test (PGNG) and the California Verbal Learning Test (CVLT). The POMS, Go/no-Go, and CVLT will be repeated 40 min following CGA application, which coincide with the approximated peak of CGA blood concentrations and at 120 min post treatment. Blood pressure, blood glucose and heart rate recordings will be taken prior to treatment and at 1, 30, 60, 90 and 120 min post-treatment. The response to GCE-enriched coffee will be compared to GCE supplement for each of the groups of variables.