May 1, 2006— Coffee made out green, unroasted coffee beans promotes weight loss, according to a new study on compounds that are naturally present in the beans.
The discovery mirrors earlier research on green tea, which was found to slightly increase metabolism and to speed up the body's ability to burn fat. Green coffee appears to have a more potent effect.
"If a human consumes one kilogram per day of food (2.2 pounds) containing 10 grams (.35 ounce) of green coffee bean extract for 14 days, the increase in body weight may be suppressed by 35 percent," said lead author Hiroshi Shimoda.
Shimoda, who is a scientist at the Oryza Oil & Fat Chemical Company, Limited, in Aichi, Japan, told Discovery News that consuming regular, roasted coffee will not lead to much, if any, direct weight loss.
He and his colleagues determined that there are two key types of compounds in unroasted coffee beans. The first is caffeine. The second is chlorogenic acid and its related compounds. Heating destroys the acids.
"Chlorogenic acid is stable and normal at room temperature, but it is unstable at high temperatures," Shimoda explained. "Normally, coffee beans are roasted at a temperature of around 240 to 250° Celsius (464-482 degrees Fahrenheit). Roasting leads to decomposition of chlorogenic acid and forms brown aromatic Maillard reactants."
He added that these fragrant chemicals give roasted coffee its characteristic flavor and aroma. Green coffee, by contrast, has no aroma and tastes slightly bitter.
For the study, Shimoda and his team fed test mice a diet that contained one percent green coffee bean extract. Some of the mice also received food in which only a small amount of caffeine or a small amount of chlorogenic acid was added.
Analysis of blood, weight and liver function in the mice revealed that caffeine and the acid alone had little effect. Together, however, the compounds reduced body weight by 35 percent when compared with a control group of mice that consumed no green coffee extract over the 13-day period.
The scientists believe caffeine releases fatty acids from fat stored in the body. The chlorogenic acid and its related compounds then, according to the researchers, help the liver to process these fatty acids more efficiently.
Findings were published in a recent edition of BioMed Central Complementary and Alternative Medicine.
Shimoda said that, based on the study results, "we recommend supplementation of the extract to food for weight loss."
Scientists at the University of Geneva, Switzerland, made a similar determination regarding green tea. Green tea is not usually roasted, so the catechin polyphenols in the tea that increase the rate of metabolism, along with caffeine, are not destroyed.
The level of caffeine is also low, with only about 30 milligrams per 6-ounce cup. Some people are sensitive to caffeine, which can increase heart rate and affect cardiovascular function.
Abdul Dulloo and his Swiss team, however, found that green tea only increases metabolism and fat burning by 4.5 percent. The researchers still suggested that green tea could serve as an aid to weight loss.
