(OR06-07-25) Consumption of Whole Green Lentils Alters Gut Microbial Composition in Metabolically At-Risk Adults: A Randomized Controlled Trial

Objectives: Pulse crops are nutrient-dense foods that may improve diet quality and reduce chronic disease risk. The health benefits of pulses are largely attributed to high fiber content, an important contributor to diet-induced shifts in gut microbial composition. However, few human interventions with pulses and pulse ingredients have examined gut microbial shifts in response to lentil consumption. We recruited metabolically at-risk adults to investigate whether long-term lentil consumption influences the gut microbial community and if microbial changes associate with host metabolic health.

Methods: We conducted a parallel randomized controlled trial with a 12-week dietary intervention. Adults (n = 36) with an elevated waist circumference (≥ 102 cm, males; ≥ 88 cm, females) and triglycerides (≥ 1.7 mmol/L) consumed mid-day meals containing 0 or 980 g/wk of whole green lentils for 12 wks. Control meals were poultry-based and matched in weekly calories and protein to lentil meals. Habitual diet was assessed by a food frequency questionnaire. Before and after the intervention, participants collected fecal samples for 16S rRNA sequencing and underwent a 5-hr high-fat meal challenge with fasting and hourly blood collection. We assessed 1) whether lentil consumption influenced community diversity and composition controlling for habitual fiber intake and diet quality and 2) associations between microbial shifts and diet-induced changes in host inflammation, lipids, and glycemic control.

Results: The addition of lentils for twelve weeks influenced gut microbial composition at the family (p = 0.03), genus (p = 0.053), and OTU-level (p = 0.01) compared to control. Among differential taxa, we found an increased abundance of Bifidobacterium with lentils. We did not detect group differences in α-diversity measures, though we found an effect for diet quality on microbial evenness (β = 0.003, p = 0.02). Last, we found that composition shifts from lentils negatively associated with postprandial GM-CSF changes (p = 0.047) and positively associated with postprandial glucose changes (p = 0.01).

Conclusions: Our data suggests that long-term lentil consumption promotes a shift in gut microbial composition, marked by an increase in a fiber-degrading bacterial taxa, that is linked to diet-induced changes in host metabolic health.

Funding Sources: USDA ARS Pulse Crop Health Initiative