We’ve known for a long time that legumes have a low glycemic index. They raise the blood sugar roughly half as much as most other foods rich in complex carbohydrates, foods such as bread and rice. What we’ve recently learned is that the effect of lowering the blood sugar continues even after the next meal. This phenomenon has been called the “second meal effect”. This was demonstrated in two studies published in the American Journal of Clinical Nutrition by Dr. David J. Jenkins, who first devised the glycemic index. It seems that once fiber from the legumes reaches the colon, it is fermented by beneficial bacteria and produces propionate: this effect decreases the rate at which the stomach empties at the next meal and thereby the level of blood sugar.