Replace Carbs With Lentils to Blunt Glucose Spike After Meals

Kristin Jenkins

July 02, 2018

Replacing a portion of the available carbohydrate from potatoes or white rice with "pulses," such as beans and lentils, can significantly lower the postprandial blood glucose response in young healthy adults, say Canadian researchers.

In a randomized crossover trial with 48 participants, the relative glycemic response was lowered by approximately 35% when 50 g of available carbohydrate from potatoes was partially replaced with lentils. Similarly, the glycemic response of a meal providing 50 g of carbohydrate from white rice was lowered by 20% when half of the rice was replaced with lentils.

The study, led by Dita Moravek, a PhD candidate in the Department of Human Health and Nutritional Sciences at the University of Guelph, in Ontario, Canada, was published recently in the Journal of Nutrition.

It also showed that both the plasma insulin incremental area under the curve and maximum concentration were significantly decreased when lentils were combined with potato, but not with rice (P < .001).

Pulses: Potential to Counteract Dysglycemia, but More Research Needed

The findings may have implications for the prevention of diabetes and other conditions caused by or exacerbated by irregular glucose levels, say Moravek and coauthors.

"These results suggest that alternative carbohydrate replacement is an effective approach for attenuating postprandial blood glucose response, which in the long term could reduce risk for both type 2 diabetes and cardiovascular disease," as well as associated complications, they observe.

Pulses are the dried seeds of legumes. They include chickpeas and dried peas as well as lentils and beans. The researchers say they chose lentil flour over other pulses because lentils display slower hydrolysis and an even lower predicted glycemic index than pea and chickpea flours.

"Pulses are extremely nutrient-dense food that have the potential to reduce chronic diseases associated with mismanaged glucose levels," said study coauthor Alison M. Duncan, PhD, RD, in a statement issued by the University of Guelph.

"We are hoping this research will make people more aware of the health benefits of eating pulses," she said.

But more studies are needed, the researchers stress.

"As efforts to increase pulse consumption continue, scientific substantiation of the health benefits is warranted; this study adds to such evidence," they write.

Nevertheless, "As this work was conducted in healthy adult participants, more information on the effects of pulses is needed in other populations such as the overweight or obese, postmenopausal women, elderly, and individuals at risk for type 2 diabetes," they add.

Similarly, assessment of pulses other than lentils is required to see whether they are equally effective in lowering postprandial blood glucose response, Moravek and colleagues conclude.

When approached for comment, Alison Evert, MS, RD, CDE, manager of the nutrition and diabetes programs at the University of Washington Medical Center in Seattle, noted that pulses are "easy to prepare, low in cost, and a healthful addition to any eating plan. There are hundreds of varieties around the world."

However, she also pointed out that the current study did not evaluate the effect of pulses on after-meal blood glucose levels when eaten as part of a more conventional meal that includes a source of protein and vegetables as well as a starch. "People do not usually eat just rice or lentils at a meal," she said.

Eating a meal that contains a source of protein along with a high GI food "will also result in lower post-meal blood glucose response," Evert told Medscape Medical News.

The study was funded by Agriculture and Agri-Food Canada. Dita Moravek, the study coauthors, and Evert have disclosed no relevant financial relationships.

J Nutr. Published online April 11, 2018. Abstract

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