Beans and peas improve control of blood sugar in diabetics and others, according to a recent report from Canadian researchers. The effect is modest.
Dietary pulses are dried leguminous seeds, including beans, chickpeas, lentils, and peas. Pulses fed to healthy volunteers have a very low glycemic index, meaning they don’t cause much of a rise in blood sugar compared to other carbohydrates. They are loaded with fiber and are more slowly digested than foods such as cereals.
Investigators examined 41 clinical trials (1,674 participants) on the effects of beans and peas on blood glucose control, whether used alone or as part of low-glycemic-index or high-fiber diets. Eleven trials looked at the effect of beans and peas alone, with the experimental “dose” averging 1oo g per day (about half a cup). The article doesn’t specify whether the weight of the pulse was the dry weight or the prepared weight. I will assume prepared.
Pulse given alone or as part of a high-fiber or low-glycemic index diet improved markers of glucose control, such as fasting blood sugar and hemoglobin A1c. The absolute improvement in HgbA1c was around 0.5%. Effects in healthy non-diabetics were less dramatic or non-existent.
This study was very difficult for me to digest. The researchers lumped together studies on diabetics and non-diabetics, using various doses and types of pulses. No wonder they found “significant interstudy heterogeneity.”
Cardiovascular disease is common in diabetics. I’m aware of at least one study linking legume consumption with lower rates of cardiovascular disease. I was hoping this study would answer for me whether I should recommend legumes such as peas and beans for my type 2 diabetics. Beans and peas do represent a low glycemic load, which is good. But I think I’ll have to keep looking for better-designed studies.
Reference: Sievenpiper, J.L., et al. Effect of non-oil-seed pulses on glycaemic control: a systematic review and meta-analysis of randomised controlled experimental trials in people with and without diabetes. Diabetologia, 52 (2009): 1,479-1,495. doi: 10.1007/s00125-009-1395-7