Eight weeks of lentil consumption attenuates insulin resistance progression without increased gastrointestinal symptom severity – A Randomized Clinical Trial

Abstract

Lentils lower acute glycemic responses and promote satiety, benefits that may aid in chronic disease prevention. However, perceived gastrointestinal (GI) effects may deter inclusion of dietary pulses in the diet. We hypothesized that 8 weeks of lentil-based vs meat-based meals would improve glycemic control and improve satiety in metabolically at-risk, nondiabetic adults. Because GI symptoms are rarely reported, we also explored the temporal effects of symptom severity. Adults with an increased waist circumference (male > 40 inches, female > 35 inches) participated in an 8-week dietary intervention that included 5 prepared midday meals each week that were isocaloric but varied in cooked green lentil dosage: 0 g (CON), 300 g (MOD), or 600 g (HI). Assessments included glucose and insulin integrated area under the curve measured during a 75-g carbohydrate tolerance test, hepatic Homeostatic Model of Insulin Resistance (HOMA-IR), and peripheral insulin resistance. On 1 randomized day each week, satiety was assessed at 4:00 pm and GI symptoms at 8:00 pm. A linear model assessed changes in glycemic and GI measures by meal group. Thirty adults (mean ± SD; age, 41.6 ± 11.7 years, body mass index, 35.1 ± 6.3) completed the intervention. HOMA-IR increased in CON (+1.2 units) and decreased in a dose-dependent manner in MOD (–0.9 units, P = .03) and HI (–1.5 units, P < .01) relative to CON. Most participants (87.4%) reported no to mild GI symptoms. Of these, flatulence was mild on average with bloating, abdominal discomfort, and cramping severity 0.3, 0.5, and 0.5 units lower (P < .001). We observed a dose-dependent reduction on rising hepatic insulin resistance and low GI symptom severity with long-term lentil consumption in metabolically at-risk adults.