|Ever since the Vinson study showed that green coffee bean extracts can help overweight women lose weight, green coffee is sexier than roasted one.|
In their 24-week rodent study, Zhang et al. (2014) tried to elucidate the mechanism by which CGA and caffeine regulate lipid metabolism. To this ends, they randomized their forty hairy subjects to diets containing no CGA or caffeine, CGA, caffeine, or CGA + caffeine.
|Figure 1: Rel. (vs. control) body weight changes and liver and intraperitoneal adipose tissue weight (Zhang. 2014)|Figure 2: Effects of chlorogenic acid (CGA) and caffeine on the hepatic protein
expression levels of AMP-activated protein kinase (AMPK), adipose TAG
lipase (ATGL) and fatty acid synthase (FAS; Zhang. 2014)
- significant decreases in the serum and hepatic concentrations of total cholesterol, TAG and leptin of mice fed the CGA + caffeine diet,
- increases of the activity of carnitine acyltransferase (CAT) and acyl-CoA oxidase (ACO),
- decreased levels of fatty acid synthase (FAS) and the respective mRNA levels
- significantly upregulated mRNA expression levels of AMP-activated protein kinase (AMPK), CAT and ACO
- pronounced reductions of PPARg2
New human data with surprising results
The researchers designed a randomised pilot crossover study with healthy subjects who consumed both coffees for 2 weeks.
- The green coffee (GC) used in this project was Ethiopian Harrar 4 (100% Arabica) and the black coffee (BC) was Sainsbury’s Original Blend Cafetitère Coffee.
- The BC was a blend of Brazilian, Colombian, Mexican, Nicaraguan, Peruvian, and Rwandan beans.
|Table 1: Concentration of total polyphenols and antioxidant capacity determined in GC and BC as compared by the three methods of coffee preparation (Revuelta-Iniesta. 2014).|
The researchers measured anthropometry, blood pressure, and arterial elasticity after each intervention and collected urine samples to monitor antioxidant capacity. The free cortisol and cortisone levels you see in Table 2 were obtained from urine and analysed by specific ELISA methods.
learn more) and the researchers hypothesis that "GC can play a role in reducing cardiovascular risk factors" (Revuelta-Iniesta. 2014) is a possible, but unconfirmed hypothesis.
- Jaquet, Muriel, et al. "Impact of coffee consumption on the gut microbiota: a human volunteer study." International journal of food microbiology 130.2 (2009): 117-121.
- Revuelta-Iniesta, R., and E. A. S. Al-Dujaili. "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 (2014).
- Vinson, Joe A., Bryan R. Burnham, and Mysore V. Nagendran. "Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects." Diabetes, metabolic syndrome and obesity: targets and therapy 5 (2012): 21.
- Zheng, et al. "Chlorogenic acid and caffeine in combination inhibit fat accumulation by regulating hepatic lipid metabolism-related enzymes in mice." British Journal of Nutrition (2014). Ahead of Print.