You may best be familiar with carbohydrates, or carbs, as their no-no identities: sugar and starch. But as much as you may have heard that these groups of carbs are the bane of your dieting existence, you should also know that your body cannot function without them. Carbohydrate rich foods include bread, potatoes, cereals and beans. The idea behind carbohydrate blockers is that you can eat the carbs, but not gain as much weight from them because their absorption is being "blocked."
Normally, carbohydrates are broken down in the small intestine by an enzyme called amylase that's released from the pancreas. By blocking the actions of amylase, the carbohydrates pass into the large intestine undigested. Digestion of carbohydrates in the large intestine is less efficient, so fewer calories are absorbed by the body. The most popular carb blocker is white kidney bean extract (Phaseolus vulgaris) and its efficacy and safety are discussed below.
What is it? Phaseolus vulgaris is the common bean, sometimes referred to as bean pod, that originally was found in Central and South America (it is now grown throughout the world). One of its varieties is the white kidney bean, an extract of which has been shown to suppress amylase, the enzyme that breaks down carbohydrates. There are 247 products on the market containing Phaseolus vulgaris according to the Natural Medicines Comprehensive Database (NMCD). However not all of these products contain white kidney bean, so you should look specifically for white kidney bean extract and not just Phaseolus vulgaris.
Does it work? There is the potential for mild weight loss using white bean extract. Much research has been done on Phase 2, a proprietary product containing white kidney bean extract made by Pharmachem Laboratories. A review of seven studies showed taking white kidney bean extract help to produce modest weight loss of between 4 and8 pounds over a period of one to three months. However, one clinical trial examined showed that there was no significant weight loss associated with white kidney bean extract use. Though the results are promising, more research is needed.
Is white kidney bean extract safe? White kidney bean extract is likely safe when used for short periods. Cantox Health Services International conducted a safety review of the ingredient and found that it can be consumed safely at doses up to 10 grams (g) per day. However this does not mean white kidney bean extract is not without side effects, or unintended consequences. Most of the side effects reported include some sort of stomach or intestinal upset such as: nausea, vomiting, diarrhea, gas and stomach pain. These side effects may disappear with continued use of white kidney bean extract, but are more likely to occur when consuming large doses of the supplement.