The process of carbohydrate digestion begins in your mouth and continues in your small intestine. The breakdown of starches into the simple sugar glucose, which your body absorbs, is dependent on a digestive enzyme called alpha-amylase, or amylase. The pharmaceutical industry has developed amylase inhibitors, or starch blockers, that slow starch digestion. Many plant foods naturally contain compounds that can also slow amylase activity. Some human studies indicate that slowing amylase activity and glucose absorption may help with weight management and blood glucose control.
Several types of salivary glands in your mouth produce and secrete a digestive enzyme called salivary amylase. This enzyme is known as an alpha-amylase. It can break chemical bonds called alpha-bonds that occur in between long chains of glucose molecules in complex starches. The main purpose of salivary amylase is to partially digest starches into shorter chains of glucose called polysaccharides, as well as a disaccharide consisting of two glucose molecules called maltose. Maltose has a sweet taste, and if you hold starch-containing foods in your mouth for a while, you may notice the increase in sweetness as salivary amylase does its job.
Normally, you do not hold food in your mouth for a long period of time before swallowing. Therefore, the majority of starch digestion must be completed in the small intestine. The presence of partially digested food in the upper part of your small intestine triggers secretion of pancreatic juices into the intestine. Pancreatic secretions contain another type of alpha-amylase called pancreatic amylase, which is highly similar but not identical to salivary amylase. Pancreatic amylase then completes the breakdown of starches into maltose. Finally, an enzyme called maltase located in cells lining your small intestine breaks down maltose into glucose, which is absorbed into your blood.
Compounds that inhibit and slow amylase activity are of interest because they slow starch digestion and glucose absorption and decrease blood sugar spikes after a meal. This is important in people with type-2 diabetes who have high blood glucose levels for long periods of time after eating. Acarbose is a commercially available prescription drug that inhibits amylase activity. Acarbose, however, has undesirable side effects, notably excessive intestinal gas production. As an alternate to the drug acarbose, flavonoid compounds that are naturally present in many of the fruits and vegetables in your diet can inhibit and slow amylase activity.
A proprietary flavonoid-rich extract from common white beans that inhibits amylase activity has been developed and tested as a dietary supplement for weight loss and blood glucose control. The bean extract was determined to be effective for inducing weight loss and reducing blood glucose spikes without producing undesirable side effects, according to a review of clinical studies published in the March 17, 2011, issue of “Nutrition Journal.” But another review of clinical studies that was published in the July 2011 issue of “The British Journal of Nutrition” concluded that larger and more rigorous trials are needed to determine the efficacy of bean extract supplements for weight loss.
- Textbook of Medical Physiology, 11th Edition; Arthur C. Guyton and John E. Hall
- Understanding Nutrition, 12th Edition; Ellie Whitney and Sharon Rady Rolfes
- National Institutes of Health: Acarbose Tablets
- Journal of Pharmacy and Pharmaceutical Sciences: Alpha-Amylase Inhibitors – A Review of Raw Material and Isolated Compounds from Plant Source
- Nutrition Journal: A Proprietary Alpha-Amylase Inhibitor from White Bean (Phaseolus Vulgaris) – A Review of Clinical Studies on Weight Loss and Glycemic Control
- The British Journal of Nutrition: The Efficacy of Phaseolus Vulgaris as a Weight-Loss Supplement – A Systematic Review and Meta-Analysis of Randomised Clinical Trials