A study conducted by medical researchers explored the effects of regular lentil consumption on metabolic health over a 12-week period. The findings indicate that lentils can contribute to lowering cholesterol levels and mitigating sugar response in the body.
The USDA suggests that adults should include approximately 300 grams of cooked pulses in their weekly diet. Lentils, classified as pulses, are recognized for their rich dietary fiber and protein content, along with the presence of bioactive compounds such as polyphenols. However, there is limited research on the extended effects of consuming lentils at the recommended USDA dose. Additionally, studies on pulse interventions have seldom addressed potential gastrointestinal symptoms associated with pulse consumption.
In this randomized clinical trial, researchers investigated the effects of a 12-week dietary intervention involving seven midday meals per week, consisting of either 980 grams or no cooked green lentils. The study focused on individuals aged 18-70 with an elevated risk of chronic metabolic disorders. Participants, both males and females, had a waist circumference of 40 inches or more for males and 35 inches or more for females, which is commonly used as an indicator of central adiposity. Additionally, all participants exhibited non-fasting serum triglyceride (TG) levels exceeding 1.69 mmol/L or 150 mg/dL.
During the 12-week intervention, participants completed weekly surveys to evaluate the effects of lentil consumption on gastrointestinal (GI) symptoms and satiety. At the beginning of the study, baseline data, including anthropometric measurements and written consent, were collected. Participants reported their habitual dietary patterns and specific diet components to identify any differences between the groups. At the second visit, postprandial serum triglyceride (TG) levels were measured to ensure that participants continued to meet the inclusion criteria.
Throughout the 12-week dietary intervention, participants underwent a high-fat meal challenge involving the consumption of a 50-gram oral fat load. Blood samples were collected after fasting and at hourly intervals for five hours postprandially to assess blood markers. General linear models were employed to analyze physical and biological changes across both groups from pre- to post-intervention. Linear mixed-effects models were utilized to evaluate the impact of timing and meals on satiety measures and the severity of gastrointestinal (GI) symptoms.
A group of 38 overweight and obese adults, with an average age of 47.2 years and a body mass index (BMI) of 34.4 kg/m2, successfully completed the 12-week intervention. Anthropometric metrics remained unchanged in both meal groups from pre- to post-intervention. Throughout the study, the average total fiber consumption was 17.3 g for the lentil group and 22.9 g for the control group. Lentil consumers experienced an increase in sodium intake, while controls showed a decrease in dairy and refined grain consumption.
During the 12-week intervention, participants in the lentil group experienced a significant increase in daily average legume consumption, ranging from 0.1 to 0.6 cups, leading to higher Healthy Eating Index (HEI) scores in four domains. Lentil consumers also had elevated total, insoluble, and soluble fiber intake. The response rates to satiety and gastrointestinal (GI) surveys were high for both groups, with 89.6% and 90.8% for the control group and 89% and 89.4% for the lentil group, respectively. Satiety measures showed no significant variation between meal groups, and GI symptom severity responses were predominantly rated as none or mild (87.7%) throughout the 12-week intervention, with only 10% and 2.3% rating them as moderate or severe, respectively.
Over the course of 12 weeks, daily lentil consumption led to a reduction in fasting measures of lipid metabolism, specifically total and low-density lipoprotein (LDL) cholesterol levels. Moreover, prolonged lentil intake showed enhancements in postprandial glucose and inflammation responses during a high-fat meal challenge. One potential explanation for these effects is the binding of fiber to bile acids, preventing their reabsorption by the liver and promoting the production of hepatic bile acids. This, in turn, leads to a decrease in serum cholesterol levels as the body replenishes hepatic cholesterol through uptake from the blood.