We have heard about all of the antioxidant benefits of green tea, but now green coffee beans? Coffee beans actually are green. They are the green seeds inside a bright red berry. It's the roasting process that turns the seeds brown and creates the characteristic aroma and flavor coffee lovers crave.

People actually don't drink green coffee, but consume the green coffee bean extract from the seeds that are left unroasted. The seeds are soaked and then concentrated to create the extract called green coffee extract (GCE). The GCE is being promoted worldwide to combat obesity. You may have seen green coffee extract at Starbucks, promoted as a natural energy source with no coffee flavor. It was also featured recently on The Dr. Oz Show.

The GCE supplement can be added to beverage products or can be taken in a capsule. It contains caffeine, but also something called chlorogenic acid. Chlorogenic acid is a polyphenol antioxidant that is normally lost during the roasting process of coffee beans.

GCE is thought to inhibit fat accumulation and reduce weight in animal models and humans. It is also linked to reducing glucose concentrations after a meal and reducing glucose absorption in the intestine. A meta-analysis (study of studies) was recently published in Gastroenterology Research and Practice, and the conclusion was that there were some promising results from GCE. However, due to the small study numbers, more rigorous trials are needed to claim the effectiveness of GCE as a weight loss supplement.

Optimal doses are unknown as are the side effects. Because GCE contains caffeine, it can cause headaches, diuresis, gastric distress, nervousness, vomiting, insomnia, anxiety, agitation, ringing in the ears and dangerous heart arrhythmias. Furthermore, caffeine-based supplements can react with other supplements. For example, taking GCE with another stimulant (like guarana) can trigger a synergistic effect that could increase blood pressure to dangerous levels. A high-caffeine intake can also trigger the loss of calcium and magnesium. There's a long list of prescription medications that interact with caffeine, from diabetes and blood pressure drugs to meds used for depression, so be careful with this supplement.

As treatment for overweight and obesity continues to evolve, so does the search for helpful dietary supplements. One thing that we do know for sure is that a healthful lifestyle that includes increased physical activity, reduction in total energy intake, plenty of fruits and vegetables and behavior therapy is the foundation of a comprehensive weight management program. Rather than spending $20 a month on a 30-day supply of GCE, why not join a gym?