Scope Aim of the study was to identify and monitor metabolite markers of dry bean consumption in parallel human and mouse studies that each had shown chemopreventive effects of dry bean consumption on colorectal neoplasia risk. Methods and Results Using liquid chromatography/mass spectroscopy +/− electrospray ionization and gas chromatography/mass spectroscopy, serum metabolites of dry beans were measured in 46 men before and after a four-week dry bean-enriched diet (250 g/d) and 12 mice that received a standardized diet containing either 0 or 10% navy bean ethanol extract for 6 weeks; we also investigated fecal metabolites in the mice. The serum metabolites identified in these controlled feeding studies were then investigated in 212 polyp-free participants from the Polyp Prevention Trial who self-reported either increased (≥+31 g/d from baseline), high dry bean intake of ≥42 g/d in year 3 or low, unchanged dry bean consumption of <8 g/d; serum was analyzed from baseline and year 3. Serum pipecolic acid and S-methyl-cysteine were elevated after dry bean consumption in human and mouse studies and reflected dry bean consumption in the Polyp Prevention Trial. Conclusions Serum levels of pipecolic acid and S-methyl-cysteine are useful biomarkers of dry bean consumption.

Given the emerging health benefits of regular legume consumption, we hypothesized that the historically low legume consumption levels in US adults increased. We evaluated legume consumption patterns in US adults using cross-sectional data from the 2011–2012 and 2013–2014-year cycles of National Health and Nutrition Examination Surveys (NHANES) and a 2017 cross-sectional, online survey of Oregon families named “Beans, Lentils, Peas (BLP) Survey”. We also compared legume consumption patterns between consumers below US dietary recommendations for mature legumes (<37.5 g/day, marginal), below levels showing nutritional and disease-prevention benefits (37.5–87.49 g/day, recommended); and levels demonstrating nutritional and disease prevention benefits (≥87.5 g/day; beneficial). In NHANES, legume consumption remained low in US adults and declined from 2011 to 2014 (mature legumes: 12.8 to 8.3%; dry beans: 10.0 to 6.5%). In BLP, less than 5% consumed legumes daily; approximately one-third did not consume legumes during the last month. Marginal mature-legume consumers ate a limited variety of legumes (dry beans and green legumes on a weekly to monthly basis). Beneficial amount consumers ate mature legumes daily or every other day and included chickpeas, lentils and dry peas to their legume mix. Our data suggest that legume consumption declined in US adults, warranting improved communication about the benefits of regular legume consumption.

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Grain legume consumption has been linked in meta-analysis studies to decreased risk of metabolic syndrome, obesity, and cardiovascular diseases; however, the evidence for a chemo-protective effect of grain legume consumption against colorectal tumorigenesis has been considered inconclusive. We conducted a meta-analysis of human and animal studies to evaluate the effect of grain legume consumption on colorectal cancer (CRC) and its precursors. Twelve case-control studies (42,473 controls and 12,408 cases) and 11 prospective cohorts (1,533,527 participants including 12,274 cases) were included in the meta-analysis; the pooled risk ratio (95% confidence interval) for the highest versus the lowest legume intake group based on a random effects model was 0.72 (0.60-0.89) for incident adenoma, 0.91 (0.84-0.99) for prevalent adenoma, and 0.82 (0.74-0.91) for CRC. Fourteen animal studies (355 animals on grain legume diets and 253 animals on control diets) were included in the meta-analysis and showed in all but one study a chemo-preventive effect against colorectal tumorigenesis. Grain legumes contain various compounds (e.g., resistant starch, soluble fiber, insoluble fiber, phytosterols, saponins, phytates, flavonoids, proanthocyanidins, and phenolic acids) that have been shown to inhibit colorectal tumorigenesis in animal studies at concentrations that are relevant for human diets. Grain legume consumption alters several molecular pathways (e.g., p53, mTOR, NF-kB, Akt, and AMPK) that are critical for tumor induction, promotion, and progression. Based on our meta-analysis, daily grain legume consumption confers chemo-preventive effects against CRC.

Conclusions and Implications: Overall, parents reported positive behavior changes by their families because of their child's participation in the program; with the greatest area of improvement in family awareness of the importance of good nutrition.