Abstract LB223: Beans to Enrich the Gut microbiome vs. Obesity's Negative Effects: First results from the BE GONE Trial in high-risk colorectal patients

Abstract

Abstract Background: Dry beans are a prebiotic food source rich in bioactive compounds with anti-inflammatory, anti-lipidemic and chemopreventive properties. The BE GONE trial tested the impact of an increase in dry bean consumption on gut microbiota and blood lipid profiles in high-risk colorectal (CR) patients otherwise consuming their usual diet. Methods: Following initiation of the pilot protocol (July 2016) among patients with a high-risk BMI and/or waist circumference and history of precancerous CR polyps, the crossover trial was expanded to patients with a history of CR cancer (May 2017). Patients were block randomized according to no vs. regular use of chronic disease medications commonly prescribed in the target population. Following a 4-week run-in/equilibration period, participants were randomized to continue the control diet (usual diet, no dry beans) or to begin the intervention diet (usual diet + dry beans). The intervention included a 2-week ramp-up to 1 cup/day navy beans (12 g dietary fiber; 14 g protein; 200 kcal) continued for an additional 6 weeks. Dietary habits, body weight, and other lifestyle parameters were monitored throughout the 20-week study. We characterized the 16Sv4 rDNA microbiome (Illumina MiSeq) and CLIA cholesterol panel in serial stool and fasting blood samples collected at baseline, week 4, and week 8 for each crossover period (n=249). Longitudinal analyses were conducted using generalized linear mixed models with random intercept and slope adjusted for chronic disease medication use examining the post-intervention effect from baseline to 4 weeks and baseline to 8 weeks. Results: Eligible patients were enrolled in the 4-week run-in/equilibration (n=69). Of these, 55 were randomized and 50 completed the 20-week trial in December 2019 with >80% compliance. Primary reasons for withdrawal were work/travel/family obligations. Half (54%) of the participants were male, 74% were CR cancer survivors, 76% were white (non-Hispanic) and 40% were on statins and/or metformin. Pre-study dietary profiles were characterized by low mean intake of legumes (<3 servings/month) and dietary fiber (17 g/day). The 8-week increase in bean intake significantly increased the inverse Simpson index [effect estimate and 95% CI: 1.59 (0.10, 3.08)], a diversity measure reflecting a greater variety of bacteria with a more even relative abundance. Longitudinal analyses restricted to taxa present in >80% of patients at baseline, revealed significantly decreased Anaerostipes and Streptococcus at week 4 and increased Faecalibacterium at week 8, along with temporal fluctuations in other known specialized (e.g., pectin) and versatile fiber-fermenting bacteria of the Lachnospiraceae and Ruminococcaceae families. A modest decrease in LDL cholesterol was observed at 8-weeks [-2.64 (-6.91, 1.62)] Conclusions: Early results of the BE GONE trial suggest that an 8-week increase in dry bean intake may be sufficient to balance or enrich the gut microbiome of high-risk CR patients. Continued sample processing and analysis, including stool metagenomics and blood metabolomics should continue to shed light on functional interactions relevant to the human host. Citation Format: Xiaotao Zhang, Kristi L. Hoffman, Fangyu Li, Ehsan Irajizad, Gladys Browman, Karen Basen-Engquist, Samir Hanash, Paul Scheet, Pablo C. Okhuysen, Scott Kopetz, Joseph Petrosino, Carrie R. Daniel. Beans to Enrich the Gut microbiome vs. Obesity's Negative Effects: First results from the BE GONE Trial in high-risk colorectal patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB223.