A Comparison of Dry Bean and Pea Consumption on Serum Cholesterol: A Randomized Controlled Trial in Adults with Mild Hypercholesterolemia

Background: Diets including pulses are associated with better cardiovascular profiles, including lipid, glycemia, and hemodynamics; however, evidence is lacking regarding the contributions of individual pulse varieties.

Objectives: This randomized, controlled trial examined the effects of beans or peas individually, relative to rice, on LDL-cholesterol levels (primary outcome) and other indices of cardiovascular disease risk (secondary outcomes) at 6 wk in adults with mild hypercholesterolemia.

Methods: This randomized, controlled, single-blind, 3-arm parallel-group study was conducted in 2 Canadian cities (Edmonton, Alberta; Winnipeg, Manitoba). Participants (n = 60 per group) were randomly assigned to 6 wk of regular consumption of foods containing either 120 g (∼0.75 cups) of beans (mixture of black, great northern, navy, and pinto) or 120 g (∼0.75 cups) peas (mixture of yellow and green), or identical foods containing white, parboiled rice (control foods). LDL-cholesterol (primary outcome) and indices of lipid metabolism, glycemia, and hemodynamics (secondary outcomes) were assessed.

Results: Mean LDL-cholesterol was lower in the bean group (-0.21; 95% CI: -0.39, -0.03) but not the pea group (-0.11; 95% CI: -0.29, 0.07) relative to rice after 6 wk. Non-HDL-cholesterol (-0.20; 95% CI: -0.40, -0.002) and total cholesterol (-0.28; 95% CI: -0.49, -0.06) were also lower in the bean compared with rice groups. No changes were noted in triglycerides (-0.07; 95% CI: -0.28, 0.14), glucose (0.02; 95% CI: -0.17, 0.14), insulin (4.94; 95% CI: -5.51, 11.38), or blood pressure (systolic: -1.39; 95% CI: -5.18, 2.40; diastolic: -1.89; 95% CI: -4.65, 0.88). Dietary fiber intake (grams per day or grams per 1000 kcal) was not correlated with LDL-cholesterol (grams per day: r² = 0.209, P = 0.142; grams per 1000 kcal: r² =0.126, P = 0.379) in the bean group. Gastrointestinal effects were transient and most often not related to the study foods.

Conclusions: Beans, but not peas, lowered LDL-cholesterol, relative to rice, in adults with mild hypercholesterolemia. Fiber may not be responsible for the effect of beans, suggesting other phytochemicals may be the active component(s). Strategies incorporating 120 g of pulses in a meal are feasible for managing some cardiometabolic risk factors. This trial was registered at clinicaltrials.gov as NCT01661543.