As background information, the authors explained that low glycemic index foods had already been linked with better glycemic control in diabetes type 2 patients. They have been included as essential foods in many nutritional guidelines for patients with diabetes. The researchers wanted to quantify the benefit.
David J.A. Jenkins, M.D., and team carried out a randomized, controlled trial with 121 diabetes type 2 patients to determine what the effect might be on glycemic control if they ate more legumes, as well as their blood lipid levels and blood pressure.
The participants were randomly selected into one of two groups:
- Low-GI legume group - they were encouraged to eat more legumes; by at least one cup a day for three months
- Insoluble fiber group - they were encouraged to eat more insoluble fiber, i.e. whole wheat foods for three months
The researchers reported that legume consumption of about 1 cup (190 grams) per day appears to contribute effectively to a low-GI diet, and to reduce the risk of coronary heart disease by bringing down blood pressure.
Below are some of the trial results:
- In the low-GI legume group, HbA1c values went down by -0.5%
- In the insoluble fiber group, HbA1c values dropped by -0.3%
- In the low-GI legume group, blood pressure fell much more than in the insoluble fiber group
"These findings linking legume consumption to both improved glycemic control and reduced CHD risk are particularly important because type 2 DM is increasing most rapidly in the urban environments of populations in which bean intake has traditionally been high (e.g. India, Latin America, the Pima Indians of Arizona).
Support for the continued use of such foods in traditional bean-eating communities, together with their reintroduction into the Western diet, could therefore be justified even if the effect on glycemia is relatively small, given the magnitude of the problem and the need for acceptable dietary options, especially those options that may also have a BP and cardiovascular advantage."
If you increase your consumption of legume-based foods, you may have better glycemic control
Invited Commentary: Diabetes Nutrition TherapyMarion J. Franz, M.S., R.D., C.D.E, Nutrition Concepts by Franz Inc., Minneapolis, Minn., in an Invited Commentary in the same journal, wrote:
"The importance of the glycemic index (GI) and fiber in diabetes mellitus (DM) nutrition therapy has been controversial. Legumes, as documented in the study by Jenkins et al, are components of a healthy eating pattern for people with DM and the general public. Whether people with DM can eat the amount necessary to improve glycemic control is debatable, and, if legumes do improve glycemia, is it because of their low GI or high soluble fiber content?
Nutrition therapy for DM is effective. However, just as there is no one medication or insulin regimen appropriate for all persons with DM, there is no one nutrition therapy intervention. A variety of nutrition therapy interventions have been shown to be effective. Nutrition education and counseling must be sensitive to the personal needs and cultural preferences of individuals and their ability to make and sustain lifestyle changes."
What are legumes?Legumes are plants in the pea family that produce pods that slit open naturally along a seam (dehisce), revealing a row of seeds. Legumes are commonly eaten by humans and animals.
Examples of legumes eaten by humans include: