Abstract
Rice bran has bioactive phytochemicals with cancer protective actions that involve metabolism by the host and the gut microbiome. Globally, colorectal cancer (CRC) is the third leading cause of cancer-related death and the increased incidence is largely attributed to poor dietary patterns, including low daily fiber intake. A dietary intervention trial was performed to investigate the impact of rice bran consumption on the plasma and urine metabolome of CRC survivors. Nineteen CRC survivors participated in a randomized-controlled trial that included consumption of heat-stabilized rice bran (30 g/day) or a control diet without rice bran for 4 weeks. A fasting plasma and first void of the morning urine sample were analyzed by non-targeted metabolomics using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). After 4 weeks of either rice bran or control diets, 12 plasma and 16 urine metabolites were significantly different between the groups (p≤0.05). Rice bran intake increased relative abundance of plasma mannose (1.373-fold) and beta-citrylglutamate (BCG) (1.593-fold), as well as increased urine N-formylphenylalanine (2.191-fold) and dehydroisoandrosterone sulfate (DHEA-S) (4.488-fold). Diet affected metabolites, such as benzoate, mannose, eicosapentaenoate (20:5n3) (EPA), and N-formylphenylalanine have been previously reported for cancer protection and were identified from the rice bran food metabolome. Nutritional metabolome changes following increased consumption of whole grains such as rice bran warrants continued investigation for colon cancer control and prevention attributes as dietary biomarkers for positive effects are needed to reduce high risk for colorectal cancer recurrence.
Highlights
Despite major advances in cancer screening and treatment, colorectal cancer (CRC) remains the third leading cause of cancer-related death in the world [1] and in the United States [2]
All rice bran food metabolites that were detected in the plasma and/or urine metabolome are listed in Supplementary Table 2
Food metabolomics of rice bran showed 453 unique metabolites and 103 rice bran metabolites were detected in plasma and/or urine after 2 or 4 weeks of consumption
Summary
Despite major advances in cancer screening and treatment, colorectal cancer (CRC) remains the third leading cause of cancer-related death in the world [1] and in the United States [2]. Bioactive food components from rice bran were identified for cancer protective functions related to energy metabolism [17,18,19], antioxidant [20], and direct anti-neoplastic activity [21,22]. Rice bran was examined as functional food in research for both CRC treatment and prevention [23,24,25,26,27]. Given the chronic disease fighting properties established for rice bran from in vitro and animal studies, this food was studied in humans and showed feasibility to increase total daily fiber intake in adults [15,26] and children [31]. Rice bran was beneficial to modulate the human stool microbiome [26,27] and metabolome [25], which provided rationale to measure metabolic changes in the plasma and urine
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