green coffee bean

Green coffee beans are unroasted coffee seeds (from Coffea arabica, Coffea canephora, or Coffea robusta). Because they are not roasted, they retain more chlorogenic acid, the compound usually marketed as the active ingredient. Green coffee bean extract is sold as a weight-loss dietary supplement and, like all coffee, naturally contains caffeine.

Evidence is weak and far from conclusive. The NIH Office of Dietary Supplements notes that only a few clinical trials have tested green coffee bean extract in people, and that these trials were all of poor methodological quality, so at best it may produce a small, modest effect on body weight. The NIH also points out that one widely promoted trial was strongly criticized by the Federal Trade Commission for critical flaws in its design, and that two of the study's three authors later retracted the published paper. Larger, more rigorous, and longer studies are needed before any genuine weight-loss benefit can be confirmed.

There is no established or recommended dose. In the limited studies summarized by the NIH, amounts of up to about 200 mg a day were used for as long as 12 weeks. Because products are not standardized and weight-loss supplements often combine many ingredients, talk with your doctor or another clinician before taking green coffee bean extract, especially if you have high blood pressure, diabetes, or heart or liver disease.

The NIH reports few safety concerns for green coffee bean extract at up to about 200 mg a day for up to 12 weeks, but stresses that it has not been rigorously studied. It contains caffeine, which can cause problems at high doses or when combined with other stimulant ingredients, so people who are sensitive to caffeine should be cautious.

Reported side effects include headache and urinary tract infections. Because the extract contains caffeine, larger amounts, or combining it with other caffeine or stimulant sources, may add caffeine-related effects such as nervousness, jitteriness, a faster heartbeat, and disrupted sleep.

The NIH does not list specific drug interactions for green coffee bean extract itself, but cautions that its caffeine content can be a problem at high doses or when combined with other stimulants, and that weight-loss supplements in general can interact with prescription and over-the-counter medications. Tell your health care provider about any supplements you take so they can help you avoid supplement-drug interactions.