More than 80 percent of diabetics are overweight or obese (NIDDK). Public health authorities have focused on dietary interventions as part of controlling both diabetes and weight. The role of carbohydrates in obesity and diabetes is of particular interest. Low-carb diets are becoming popular because they reportedly help with weight loss and blood sugar control. But the low-carb lifestyle isn't for everyone. Carbohydrate blockers have entered the market as a possible solution. If their marketing claims are believed, carbohydrate blockers have the potential to allow diabetics to enjoy carbohydrates without ruining their blood sugar control while also helping to control weight.
Bean Extract
"Blocker" is something of a misnomer. Carbohydrate blockers slow the absorption of carbohydrates by inhibiting the enzymes amylase and sucrase, which are responsible for breaking carbohydrates down during digestion. A Georgetown University Medical Center researcher wrote in the June 2009 "Journal of the American College of Nutrition" that carbohydrate blockers may become more important treatment options as the public struggles with diabetes and obesity. If they work properly, they would allow you to enjoy a reasonable serving of carbohydrate in each meal, rather than having to cope with less. Many of the carbohydrate blockers on the market today are made from a white kidney bean extract, Phaseolus vulgaris. In animal studies, wrote the author, the extract reduced after-meal blood sugar concentrations by as much as 40 percent, and repeated use didn't diminish the extract's effectiveness. In addition to lowering the amount of calories you absorb, they could ease concerns with insulin resistance, given that less insulin is required after your meals.
Performance in Research
Signs of effectiveness of carbohydrate blockers in people have been mixed. The "Journal of the American College of Nutrition" article reviewed several from the 1970s and '80s. In one group of studies, 1.5 grams of the bean extract reduced carb absorption by 66 percent in response to sliced white bread. When given a full meal and .75 grams of the extract, absorption was reduced by 28 to 41 percent. In a Norwegian study aimed at weight loss, the bean extract was given to participants following a 1,200-calorie diet and getting more exercise. After 12 weeks, participants lost an average of 7.7 pounds compared with a placebo group that lost 2.86 pounds. In analyzing results from literature to date, the author ironically concluded that the bean extract worked better when study participants followed a high-carbohydrate diet.
Practical Effectiveness
NYU's Langone Medical Center, however, reports the extract's potential is still only theoretical and convincing proof of its effectiveness has yet to be revealed. The center suggests that when you take the extract, the product may supply enough of its own amylase to counteract any that has been inhibited in your stomach. In addition, another enzyme, glucoamylase, can take over when your own amylase can't do its job. The center states, rather categorically, "Use of amylase inhibitors did not in fact block the digestion of starch" in the earliest studies. Since then, however, newer products with higher doses of Phaseolus vulgaris have entered the market and a new crop of studies are examining their effectiveness. To date, a 2006 study failed to find any blood sugar benefit of the extract
Acarbose
A medication, acarbose, can be prescribed for diabetics to work in a manner similar to over-the-counter bean extracts. Sold under the names Prandase and Precose, acarbose is a starch blocker that targets yet another digestive enzyme, alpha glucosidase. However, the same qualifications exist. According to the Diabetes Teaching Center at the University of California, San Francisco, acarbose simply slows carbohydrate absorption, which lowers your after-meal blood sugar. It doesn't reduce how much total carbohydrate you absorb. The drug is used to help bring blood sugar back to a normal range. One of its nastier side effects is gas, so combined with its modest effects on long-term blood sugar control, the center says the medicine is rarely used.
Safety
White bean extracts also cause flatulence, says NYU's Langone Medical Center, though the extract is generally considered to be safe. The center describes the gas problem as "notorious." Acarbose may also cause stomach cramping and diarrhea. In addition, when acarbose is taken with other diabetic medications, including insulin, it may cause your blood sugar to drop too low. You may experience signs of hypoglycemia, says MedlinePlus, including light-headedness, shaking, sweating, headache, weakness, clumsy movement and numbness around your mouth.
References
- "Journal of the American College of Nutrition"; Bean Amylase Inhibitor and Other Carbohydrate Absorption Blockers: Effects on Diabesity and General Health; Harry G. Preuss; June 2009
- "Huffington Post"; The Diabesity Epidemic Part I: How Diabetes And Obesity ; Mark Hyman; December 2009
- Diabetes Education Online, Diabetes Teaching Center at the University of California, San Francisco: Starch Blocker
- NYU Langone Medical Center: Phaseolus Vulgaris
- MedlinePlus: Acarbose
