Background: We have recently shown that consumption of green coffee bean extract rich in chlorogenic acid reduces blood pressure and urinary free cortisol levels1. Increased 11β HSD1 (Hydroxysteroid dehydrogenase type1) activity is implicated in the development of obesity, cardiovascular disease and diabetes. The aim of this study was to compare the effects of consuming green (GC) and black (BC) coffees on cardiovascular, anthropometrical markers and urinary free glucocorticoids levels.
Methods: A randomised controlled crossover study in which 20 males and females(2165 y) consumed 4 cups of ground BC (32 g/day) and GC (40 g/day) for 2 weeks with one week of washout period between interventions. Measurements of body composition, blood pressure, arterial elasticity at baseline and at end of intervention were recorded. Urine samples were also collected (24 h) to estimate free cortisol and cortisone levels by specific ELISA methods.
Results: GC significantly reduced systolic blood pressure and arterial elasticity from 117.3±11.39 mmHg and 6.6±1.04 m/sec to 113.48±13.35 (P=0.018) and 6.33±1.19 m/sec (P=0.02) respectively, while diastolic blood pressure was reduced from 73.81±7.47 mmHg to 71.17±7.62 mmHg after BC (P=0.018) and to 70.08±8.89 mmHg after GC (P=0.002). BMI (P=0.01), abdominal fat (BC, P=0.01; GC, P=0.009) and waist circumference (BC, P=0.04; GC, P=0.009) were all significantly reduced after both interventions; however no change was seen in total energy intake. Urinary free-cortisol was significantly reduced from 125.6±85.9 nmol/day to 76.01±54.98 nmol/day following GC and increased to 132.07±89.09 nmol/day with BC. There was no significant difference in urinary cortisone levels. The ratio of cortisol/cortisone was significantly reduced after GC (from 3.54±1.92 to 1.73±1.04, P=0.002) suggesting an inhibition of 11βHSD1 activity.
Conclusion: This study proposes that consumption of green coffee can play a role in reducing cardiovascular risk factors probably due to the inhibition of 11β HSD1 activity. Further research on hypertensive and overweight individuals will now be justified to clarify whether GC consumption could have a preventative or a therapeutic role in the fight against CVD and obesity.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.