White Bean Supplement May Help Lower Glycemic Index
Lee Swanson Research Update
The glycemic index (GI) of foods could be reduced through the intake of a powdered form of a white kidney bean dietary supplement, a new study claims.
According to findings published in the Nutrition Journal, a dietary supplement derived from the white kidney bean, when consumed by volunteers, decreased the GI of white bread.
The researchers, based at the UCLA School of Medicine, say that epidemiological studies suggest that low GI diets decrease the risk of developing type 2 diabetes and coronary heart disease, while controlled clinical trials indicate that low GI diets lower cholesterol.
According to the scientists, during in-vitro analysis, the white kidney bean-derived supplement called Phase 2 was shown to inhibit the digestive enzyme alpha-amylase, which is secreted in the saliva by the pancreas and is responsible for breaking down starches into sugars that are consequently absorbed in the small intestine.
"Since the GI is a function of the rate of absorption of glucose in the gut, inhibition of alpha-amylase may result in the lowering of GI," they hypothesized.
The authors said the objective of this study was to thus determine whether the addition of Phase 2 in-vivo would lower the GI of a commercially available high-glycemic food such as white bread.
Predicting the GI through the in-vivo method involved feeding the test food to a number of human volunteers and taking regular blood samples to monitor changing blood sugar levels.
The researchers explained that they conducted an open-label 6-arm crossover study with 13 randomized subjects aged between 24 and 44 with a BMI between 18 and 25 (kg/m2). And they said that standardized GI testing was performed using white bread with and without the addition of Phase 2 in capsule and powder form.
Subjects with any active eating disorders, gastrointestinal illness or history of gastrointestinal surgery, diabetes or other endocrinologic disorders were excluded, the authors continued.
They said that the study population received 50 g net carbohydrates in the form of white bread with butter either by itself or with a form of Phase 2 in seven different sessions at the testing facility.
"Although fat may affect the GI of foods there was consistency in the study in that it was included in both the control and test groups," stressed the researchers.
They said that the dietary supplement was given at dosages of 1,500 mg, 2,000 mg and 3,000 mg in capsule form and 1,500 mg, 2,000 mg and 3,000 mg in powder form, with the powder form of the test product mixed into the butter, which was spread on the bread.
"The capsules were taken immediately prior to the ingestion of food. During each visit subjects had their capillary blood glucose measured nine times over two hours," explained the authors.
The researchers found that the data demonstrated the most significant decreases in the GI of white bread with the powder form of Phase 2 at the dosage of 3,000 mg.
"The data suggest a possible dose-dependent effect with a preference for the powder form. The lesser effect with the capsule formulation may reflect a reduced bioavailability of the white bean extract, perhaps due to the time required for capsule dissolution," they said.
Nutrition Journal Published online ahead of print.