Abstract CT138: Increasing dietary rice bran and navy bean intake for colorectal cancer control and prevention: A randomized-controlled pilot investigation

Adhering to the American Institute for Cancer Research (AICR) Recommendations for Cancer Prevention, including increasing dietary intake of whole grains and beans, has been shown to reduce colorectal cancer (CRC) burden. Dietary rice bran (RB) and navy beans (NB) are examples of these foods with high dietary fiber content and other important phytochemicals that have inhibited colon carcinogenesis in animal and human epidemiological studies. Alongside widespread affordability and accessibility, we formed a community-academic partnership to advance RB and NB dietary chemoprevention research in a pilot phase II study titled BENEFIT: Beans/Bran Enriching Nutritional Eating For Intestinal health Trial (NCT01929122). We established feasibility of increased consumption in CRC survivors and examined changes in dietary intake and gut microflora. Twenty-nine participants completed the 4-week, randomized-controlled dietary intervention that included consuming RB (30g/day), NB powder (35g/day), or neither (control) via study provided meals and snacks. Fasting blood, urine, and stool were collected at baseline, 2-week, and 4-week time points. The amount of RB or NB consumed (ranging from 4-9% daily caloric intake) led to increased dietary fiber, iron, zinc, thiamin, niacin, vitamin B6, folate, and alpha-tocopherol intake, as measured by NutritionistProTM. Stool microbiome analysis from RB group showed significant genus level increases in Methanobrevibacter, Paraprevotella, Ruminococcus, and Bifidobacterium compared to the control group, as well as increased gut bacterial richness and diversity. The NB group increased gut bacterial richness and revealed increases in three previously unidentified species. Plasma, urine, and stool metabolome changes revealed increases in a number of microbial, host, and diet derived metabolites, such as phytosterols, fatty acids, amino acids, bile acids, and small molecule byproducts of carbohydrate metabolism. In addition, human stool metabolite extracts were assessed before and after RB or NB consumption to observe reduced growth of CRC cells. Dietary biomarkers of RB and NB consumption are under investigation and have revealed specific metabolite profiles including pyridoxine (vitamin B6), beta-hydroxyisovaleroylcarnitine and beta-hydroxyisovalerate (RB), and pipecolate and S-methylcysteine (NB). These results support dietary RB or NB modulation of metabolism from digestion, microbiota, and microbial biotransformation. Our pilot findings warrant further evaluation of these specific foods in a larger cohort and for a longer duration of consumption to assess CRC control and prevention markers in the colon tissue. Next phase studies underway include dietary modulation of human colonic inflammation for CRC chemoprevention. Citation Format: Erica C. Borresen, Renee C. Oppel, Dustin G. Brown, Regina J. Brown, Elizabeth P. Ryan. Increasing dietary rice bran and navy bean intake for colorectal cancer control and prevention: A randomized-controlled pilot investigation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT138. doi:10.1158/1538-7445.AM2017-CT138