“Legumes are the star performers for blood glucose control” – Professor Jennie Brand-Miller, University of Sydney
As a high fibre, low glycemic index (GI) source of protein, legumes make an excellent choice to include for the dietary management of blood glucose control. Legumes have been shown to improve short-term blood glucose control, and as part of a low GI diet are linked to long-term improvements in HbA1c and reduced risk of type 2 diabetes.
A meta-analysis of 11 trials reported consumption of up to 1/2 a cup (75g cooked) of legumes per day for more than four weeks significantly reduces fasting blood glucose and insulin levels. A further meta-analysis of 19 randomised controlled trials found when legumes were included in a lower GI diet they lowered HbA1c significantly for up to 52 weeks in both diabetic and non-diabetic individuals.
Suggested Mechanisms
The main mechanism by which legumes moderate the glycemic response is due to the nature of the starch in legumes which is encapsulated and is higher in amylose than grains. This means it is less likely to be fully gelatinised during cooking which reduces the rate of starch digestion and therefore the glycemic response. It has also been proposed the protein in legumes stimulates insulin secretion, facilitating a more rapid extraction of glucose from the bloodstream into cells compared to other carbohydrate foods.
Legumes may also reduce the risk of diabetes through the second-meal effect. The second meal effect is the ability of legumes to lower both postprandial glycemia after the meal at which they are consumed and also at a subsequent meal later in the day or even on the following day.
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