A member of the parsley family, gotu kola is a common weed that grows in drainage ditches in Asia and orchards in Hawaii.
Folk tradition says that if you eat a leaf of gotu kola every day, you'll live to be 1,000! It's reputed to be an anti-aging herb, an aphrodisiac, a memory restorative, and a wound healer. As you might guess, there's no evidence to support these claims. A known effect of this herb is that it fights water retention by helping the body eliminate excess fluid. It is also a central nervous system stimulant and is believed to be a lipotropic herb.
Gotu kola is relatively safe if taken on a short-term basis. However, it should be avoided if you have a chronic medical condition because of its stimulating effect. Side effects include insomnia and nervousness.
Green Tea Extract
Green tea comes from the leaves and leaf buds of an evergreen tree native to Asia. An extract standardized for a beneficial group of chemicals called polyphenols is made from the tea and put into capsules or used as a filler in some natural weight-loss supplements.
Green tea and its extract have a number of beneficial properties. Research shows that they may protect against certain cancers, enhance cardiovascular health, and boost fat metabolism (which is one reason you find it in natural weight-loss supplements). Green tea contains some caffeine, but less than half of what you get in coffee. Caffeine is believed to help release fatty acids into the bloodstream for use as energy.
Unless you're sensitive to caffeine, green tea or extracts containing it are very safe and probably beneficial to health.
Guarana is a red berry from a plant grown in the Amazon valley. It contains seven times as much caffeine as the coffee bean and is widely sold in health food stores as a supplement to increase energy. The supplement is made from the seeds of the berry.
Guarana is used in a number of natural weight-loss supplements, often combined with ephedra. The combination is believed to increase thermo-genesis (body heat), and thus to stimulate the metabolism. Guarana may also cause your body to lose water, since the caffeine it contains is a diuretic.
It is unwise to use guarana, especially with ephedra, because of its stimulating effects. Also, very high doses may disturb the heart and even cause panic attacks.
Gymnema silvestre is an herb derived from the leaves of a tree native to Africa and India. It is a member of the botanical family Asclepiadacerae, named after the Greek god of healing, Asclepius. The herb may reduce your desire for sugar by blocking the taste for sweets. In fact, the Hindu name for this herb is gurmar, which means "sugar killer."
Gymnema has long been used in India to help treat diabetes, and many modern studies show that it can increase the production and activity of insulin, reduce blood sugar levels, and lower levels of blood fats. The active ingredient in gymnema, gymnemic acid, has been shown to block sugar absorption in the body.
As for weight loss, gymnema may be of some benefit if you have a sweet tooth and need to cut your consumption of sugary treats, (This benefit is largely untested, however. Even so, gymnema may be worth a try if you crave sweets.) Herbalists recommend taking gymnema extract before a large meal to reduce the appetite as well as quell cravings for sweets. Gymnema also has a reputation as a diuretic.
Gymnema is safe, and herbalists advise taking 150 mg of the extract three times a day. If you're a diabetic, do not supplement with gymnema without checking with your physician, since the herb affects sugar metabolism.