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Effect of Green Coffee Bean Extract on Hypertension
Recent studies suggest that Green Coffee Bean Extract may have a multitude of health benefits, mainly in dealing with health challenges that stem from oxidative stress (such as heart disease or...
Read more about Hypertension and Green Coffee Bean Extract.
Research Evidence on Impacts of Green Coffee Bean Extract on Various Health Challenges
Because Green Coffee Bean Extract’s popularity is a recent phenomenon, the body of research supporting its health benefits or detriments is minimal. Still, a few human studies and several more animal studies researching the impact of GCBE on health have been conducted. The strongest (but still relatively weak) body of evidence supports GCBE's positive impacts on weight and blood pressure, with some sparse evidence suggesting its benefits as a diabetes treatment. For simplicity, the health challenge addressed by each study is presented in bold before the study’s summary.
Weight Loss. A clinical study released in January 2012 showed outstanding results for GCBE’s potential in reducing body weight, and is largely responsible for the current buzz around the product. 16 subjects (8 male/female) with a mean age of 33 years old were studied over the course of 22 weeks. Over the course of the study, subjects consumed a high daily dose (1050 mg), a low-dose (700 mg), and a placebo for three 6-week periods. The results of the study showed an average weight loss of 8.04 kg, a decrease in body mass index by 2.92 kg/m2, a reduction of percent body fat by 4.44%, and a slow down of heart rate by 2.56 beats per minute. At the beginning of the study all 16 participants were classified as overweight, and by the end of the study 6 of those people had entered the normal weight range.
Though promising, it should be noted that the daily dose of 700-1050 mg per day was much higher than other studies, which normally used doses ranging from 180-200 mg/day. With that said, the participants in this study did not experience any adverse side effects.
Weight Loss. A study of 30 individuals with medium to above average weight (BMI 27.5-32.5 kg/m^2) showed GCBE to have a moderately significant impact on weight. Half of the group consumed regular black coffee for 12 weeks (placebo), while the other half drank black coffee fortified with GCBE. The results showed an average weight loss of 5.4 kg for the GCBE group, compared to a 1.4 kg average loss for the placebo group. An additional portion of the study suggested that this weight loss may be due to changes that GCBE causes in intestinal glucose absorption (put simply, it may reduce the amount of sugar we absorb).
Though promising, the previous two studies should be taken with a grain of salt, as both used a small sample size.
Hypertension/High Blood Pressure. In a double-blind, placebo-controlled study of 117 males with mild hypertension, GCBE was given for one month at 46 mg, 93 mg, or 185 mg daily. 2 After 28 days, the results showed a significant improvement in blood pressure as compared to placebo in the 93 mg and 185 mg groups. The results seen were dose-related, meaning that the greater the dose, the greater the improvement. The finding of dose-relatedness tends to increase the likelihood that a studied treatment is actually effective.
Hypertension/High Blood Pressure. In another double-blind, placebo-controlled study, 28 Japanese with mild hypertension (defined as systolic blood pressure of 140-159 mmHg and/or diastolic blood pressure of 90-99 mmHg) were participants in a GCBE study. Over the course of 12 weeks, half of the group consumed fruit juice containing Green Coffee Bean Extract, while the other half drank fruit juice with no extract added (placebo). Around 500 mg of GCBE was added to the juice. Results showed that while the placebo group showed no reduction in blood pressure, the GCBE consuming group both had statistically significant reductions to their systolic and diastolic blood pressures4.
Hypertension. A study on two different rat species showed that both a single oral dose and a long-term daily dose (6 week) of GCBE caused a reduction in blood pressure. However, the experiment did not actually use GCBE, but rather an active ingredient in the extract that is thought to cause the anti-hypertensive effects. What makes this study interesting is that it compared the impact of Green Coffee Bean Extract to Roasted Coffee extract. The results showed that roasted coffee extract had no correlation with reduced blood pressure, revealing the especially unique nature of GCBE.
Other. GCBE products are sometimes said to help prevent diabetes; however, this claim derives only from weak evidence involving consumption of ordinary coffee, 1 and cannot be relied upon at all.
Roasted (as opposed to green) coffee beans contain the substances kahweol and cafestol, which appear to increase levels of LDL ("bad" cholesterol). 2 The fact that GCBE does not contain these substances is used as an argument in its favor. However, these substances remain in the coffee grounds and so they are also not present in standard beverage coffee, so this is probably not a significant point. (Unfiltered or boiled coffee, with the grounds left in, however, may present a risk.)
- van Dam RM, Feskens EJ. Coffee consumption and risk of type 2 diabetes mellitus. Lancet. 360(9344):1477-8.
- Ranheim T, Halvorsen B. Coffee consumption and human health--beneficial or detrimental?--Mechanisms for effects of coffee consumption on different risk factors for cardiovascular disease and type 2 diabetes mellitus. Mol Nutr Food Res. 49(3):274-84.