Written by Angeline A. De Leon, Staff Writer. Green coffee consumption significantly improved blood pressure and arterial elasticity and significantly decreased body weight and urine cortisol levels in the participating healthy individuals.
Chlorogenic acid (CGA), a polyphenolic compound found in coffee beans, is associated with potent antioxidant activity 1 and high levels of bioavailability 2. This natural compound also exhibits anti-hyperintensive properties 3 as well as a capacity to support body fat loss through improved absorption and utilization of glucose 4. Such attributes make it a highly studied supplement for its potential protective role against cardiovascular disease. Unlike the beans of regular black coffee, green coffee beans are unroasted, resulting in a higher retention of CGA5. While CGA-rich green coffee is associated with blood pressure-lowering effects 6, traditional black coffee, containing higher levels of caffeine relative to green coffee, is known to induce an acute rise in blood pressure following initial exposure 7, but with long-term consumption, has been linked to lower blood pressure 8. In a study conducted by researchers at Queen Margaret University in the United Kingdom (2014), researchers compared the effects of green coffee and black coffee on cardiovascular markers like blood pressure and arterial elasticity, as well as body composition and glucocorticoid levels in healthy subjects.
A total of 18 healthy volunteers were enrolled in a randomized crossover pilot study. Subjects were randomized to receive 40 g of either black coffee (blend of Brazilian, Colombian, Mexican, Nicaraguan, Peruvian, and Rwandan beans) or green coffee (100% Arabica) daily for 14 days, after which they were assigned to participate in the alternative arm of the study (washout period of one week in between). At baseline and following each of the two intervention periods, subjects completed a 2-day diet diary as well a health status questionnaire. Anthropometric and body composition measurements were obtained and blood pressure and arterial elasticity recorded. A 24-hour urine sample was also collected at baseline and at the end of each intervention period for analysis of polyphenol concentration and urinary cortisol and cortisone (inactive form) levels.
Final analyses showed that green coffee was associated with significantly lower systolic blood pressure (mean reduction of 2.65 +/- 1.37 mmHg, p = 0.018) and arterial elasticity (mean reduction of 0.26 +/- 0.12 m/second, p = 0.001). Both black coffee and green coffee also significantly reduced body mass index (p = 0.04, p = 0.01, respectively) and abdominal fat (p = 0.01, p = 0.009, respectively). No significant differences in polyphenol concentration were detected from urine samples, however, cortisol levels significantly decreased by 39% (from 125.6 +/- 85.9 to 76.0 +/- 54.9 nmol/day) following the green coffee intervention and increased by 5% (from 125.6 +/- 85.9 to 132.1 +/- 89.1 nmol/day) following the black coffee intervention (p = 0.01).
Overall, evidence from this pilot trial shows that although both green and black coffee led to significant decreases in body mass index and abdominal fat, only green coffee was able to also significantly improve systolic blood pressure and arterial elasticity and decrease stress hormone (urinary cortisol) levels. Researchers suggest that even short-term intake of green coffee may be beneficial for protecting against cardiovascular risk. Notable limitations of the study include a relatively small sample size and a non-blinded study design which could have potentially biased current results. Follow-up studies using a longer intervention period and a population group at risk for cardiovascular disease would be recommended.
Source: Revuelta-Iniesta R, Al-Dujaili EAS. Consumption of green coffee reduces blood pressure and body composition by influencing 11β-HSD1 enzyme activity in healthy individuals: a pilot crossover study using green and black coffee. BioMed Research International. 2014; 482704: 1-9. DOI: 10.1155/2014/482704.
Copyright © 2014 R. Revuelta-Iniesta and E. A. S. Al-Dujaili. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Posted December 4, 2018.
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