Impact of Lentils on Blood Glucose Levels
Introduction
Researchers have explored whether substituting carbohydrates from white rice and potatoes with lentils can reduce blood glucose levels after meals. The focus on blood sugar control has intensified due to its significance in managing and preventing type 2 diabetes. Dramatic fluctuations in blood glucose can challenge the body’s insulin production capabilities. Insulin plays a crucial role in lowering blood glucose levels, and its production can be disrupted in diabetes. Therefore, achieving glycemic control is a key goal of dietary interventions for type 2 diabetes.
Understanding Glycemic Index and Blood Glucose
The glycemic index (GI) of foods indicates how they influence blood glucose levels following consumption. High-GI foods, such as potatoes and white rice, can cause significant spikes in blood glucose. In contrast, low-GI foods, including seeds and legumes, have minimal effects on blood glucose levels. Previous research has indicated that consuming foods classified as “pulses,” such as beans, peas, and lentils, is linked to improved long-term glycemic control. Lentils, in particular, are recognized for their slowly digesting starch, low hydrolysis rate, high protein content, and relatively low predicted glycemic index compared to other pulses like chickpeas.
Canadian Research Investigation
A study conducted by Canadian researchers examined the effects of replacing a portion of high-GI foods, specifically potatoes and white rice, with lentils on post-meal blood glucose levels. Their findings were published in the Journal of Nutrition. In this study, researchers replaced half of the serving of potatoes and white rice with lentils to maintain realistic consumption levels. They recruited two groups of 24 healthy adult volunteers, dividing them into potato and rice groups. Participants attended five three-hour morning study sessions, consuming meals that included only white rice, only potatoes, rice with lentils, and potatoes with lentils. The study utilized three varieties of lentils: large green, small green, and split red, and blood samples were collected to assess glucose and insulin levels.
Results: Lentils and Blood Glucose Control
The study’s results revealed that substituting half of the rice and potatoes with lentils led to reduced post-meal blood glucose levels across all three lentil types. Specifically, the relative glycemic response decreased by approximately 20% for rice combined with lentils and 35% for potatoes combined with lentils when compared to each carbohydrate consumed alone. It is noteworthy that plasma insulin levels decreased solely in the potato and lentil combination.
Conclusions and Future Research
While the authors were unable to identify the biomechanical mechanism behind the reduction in post-meal blood glucose associated with lentil consumption, it was clear that this effect was not attributed to excessive insulin production. Overall, the study concluded that replacing a portion of high-GI foods like white rice and potatoes with low-GI pulses such as lentils is effective for post-meal blood glucose management. This finding is beneficial for individuals with diabetes and may aid in preventing the onset of diabetes by regulating insulin production over time. The researchers recommend conducting future studies to evaluate the same carbohydrate replacement strategy in individuals with diabetes to determine its effectiveness in that population.
References
Moravek, D., Duncan, A. M., Vandersluis, L. B., Turkstra, S. J., Rogers, E. J., Wilson, J. M., Hawke, A., Ramdath, D. D. (2018). Carbohydrate Replacement of Rice or Potato with Lentils Reduces the Postprandial Glycemic Response in Healthy Adults in an Acute, Randomized, Crossover Trial. The Journal of Nutrition, (148), 535-541. doi: https://doi.org/10.1093/jn/nxy018.