Move over, green tea extract. Green coffee extract (GCE) may be about to steal a little of your thunder as a weight loss supplement. Although there has been more research conducted on animals than on humans at this point, scientists are hopeful about the effects in the little green (unroasted) coffee bean and continue to develop studies looking into the supplement’s safety and efficacy. But it’s not just the extract’s ability to promote weight loss that looks promising. GCE may also help to lower blood pressure and improve heart rate and blood sugar metabolism.
It’s all in the polyphenols
GCE is derived from unroasted coffee beans. The extract from the green coffee bean is rich in antioxidants called polyphenols. One of these polyphenols is a compound called chlorogenic acid (CGA), which is found in other plants but in higher concentrations in coffee beans. CGA helps the body absorb cell-damaging free oxygen radicals and ward off hydroxyl radicals (the most damaging form of free radicals), says supplement researcher Ray Sahelian, MD. And it’s chlorogenic acid that could be responsible for the range of benefits to be derived from use of the extract.
Green coffee extract and weight loss
Much of the recent interest in GCE comes from research presented at this year’s national meeting of the American Chemical Society. During a 22-week study period, 16 overweight subjects alternated between taking 1,050-mg or 700-mg doses of GCE, or a placebo (an inactive ingredient). The subjects made no significant changes in their diets. By the study’s end, all 16 of the overweight study subjects had lost weight (on an average of 17 pounds), reduced their body mass index, or BMI (a measure of
fat based on weight and height), and lowered their percentage of body fat. Thirteen of the subjects also experienced an added benefit—a decrease in resting heart rate. The study was also reported in the journal Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy. “Based on our results, taking multiple capsules of green coffee extract a day — while eating a low fat, healthful diet and exercising regularly — appears to be a safe, effective, inexpensive way to lose weight,” commented study author Joe Vinson, PhD, a chemist at the University of Scranton in Pennsylvania.
In general, the supplement shows no adverse side effects—as long as it’s not blended into a formula containing ingredients that increase heart rate and blood pressure. That said, subjects in this study did experience what the investigators termed a “slight (4.88 ± 11.24 mmHg) though nonsignificant increase” in systolic blood pressure; they point out, however, that the increase was confined to the phase of the study in which subjects used the placebo. And while a 2001 study found that chlorogenic acid increased blood levels of homocysteine, a predictor of cardiovascular disease, it is not known whether CGA increases your risk for the disease.
Green coffee extract and blood pressure
Interestingly, research conducted on both animals and humans points to a blood pressure-lowering effect of the supplement. In a Japanese study published in the journal Clinical and Experimental Hypertension, individuals with mild hypertension (elevated blood pressure) who took CGA in green coffee bean extract experienced a significant decrease in both systolic and diastolic blood pressure. Study subjects who received higher doses of the extract had a greater blood pressure drop than study participants receiving lower doses.
Green coffee extract and blood sugar
In a study on diabetic mice reported in the journal PLoS One, chlorogenic acid found in GCE decreased fasting blood sugar and stimulated glucose transport in skeletal muscle. While further study is required, the researchers hypothesize that this ability to improve glucose metabolism may account for the decrease in BMI and body fat found in subjects taking GCE in other studies.
Can’t I just drink coffee?
We know that chronic coffee and caffeine consumption can raise blood pressure, potentially increasing the risk of stroke and heart disease, particularly in people with hypertension. That’s probably a good reason not to consume excessive amounts of either. But the average 200-mg dose of the CGE is unlikely to raise blood pressure, since it contains about 20 mg of caffeine. (In contrast, an 8-ounce cup of generic brewed coffee contains 95 to 200 mg of caffeine.) You’d likely need to drink a lot of coffee to get the CGA contained in a 200-mg dose of the supplement. According to the Linus Pauling Institute Micronutrient Information Center, the CGA content of a seven-ounce cup of coffee ranges from 70 to 350 mg. (Once the coffee bean is roasted to make coffee, much of the chlorogenic acid contained in the raw bean is destroyed. The longer the bean is roasted, the less chlorogenic acid remains. Plus, different types of coffee beans will produce a beverage with varying amounts of CGA.) Thus, your average Joe is an unreliable source of CGA.
Green coffee extract is an ingredient in a number of supplement formulas, and is also available as an individual supplement. It has enjoyed the spotlight since Dr. Mehmet Oz spoke of its potential weight-loss benefits, for which he recommends taking two 400-mg capsules two or three times a day, with a full glass of water, 30 minutes before meals. While he did not endorse specific products containing the extract, Dr. Oz did advise buying a product manufactured without fillers or other additives. Naturally, he adds, you’ll get the best results when you also exercise and consume a healthy diet.
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