Navy Beans Impact the Stool Metabolome and Metabolic Pathways for Colon Health in Cancer Survivors.

Bridget Baxter,Renee Oppel,Elizabeth Ryan

doi:10.3390/nu11010028

Abstract

Colorectal cancer (CRC) is the third leading cause of cancer-related death in the United States and emerging evidence supports that increased consumption of legumes, such as navy beans, can reduce risk. Navy bean consumption was previously shown to modulate host and microbiome metabolism, and this investigation was performed to assess the impact on the human stool metabolome, which includes the presence of navy bean metabolites. This 4-week, randomized-controlled trial with overweight and obese CRC survivors involved consumption of 1 meal and 1 snack daily. The intervention contained 35 g of cooked navy bean or macronutrient matched meals and snacks with 0 g of navy beans for the control group (n = 18). There were 30 statistically significant metabolite differences in the stool of participants that consumed navy bean at day 28 compared to the participants’ baseline (p ≤ 0.05) and 26 significantly different metabolites when compared to the control group. Of the 560 total metabolites identified from the cooked navy beans, there were 237 possible navy bean-derived metabolites that were identified in the stool of participants consuming navy beans, such as N-methylpipecolate, 2-aminoadipate, piperidine, and vanillate. The microbial metabolism of amino acids and fatty acids were also identified in stool after 4 weeks of navy bean intake including cadaverine, hydantoin-5 propionic acid, 4-hydroxyphenylacetate, and caprylate. The stool relative abundance of ophthalmate increased 5.25-fold for navy bean consumers that can indicate glutathione regulation, and involving cancer control mechanisms such as detoxification of xenobiotics, antioxidant defense, proliferation, and apoptosis. Metabolic pathways involving lysine, and phytochemicals were also modulated by navy bean intake in CRC survivors. These metabolites and metabolic pathways represent an acute response to increased navy bean intake, which merit further investigation for improving colonic health after long-term consumption.

Highlights

Dry beans are staple foods and well recognized sources of vital macronutrients [1] and micronutrients such as folate, iron and magnesium [2]
Using a non-targeted metabolomics approach, we demonstrated that navy bean consumption for 4 weeks modulated the stool metabolome of Colorectal cancer (CRC) survivors across multiple metabolic pathways of relevance to improving colon health and reducing CRC risk
Beans contain a number of components, such as 2-aminoadipate, ophthalmate, eicosapentaenoic acid, scyllo-inositol, gamma-glutamylglutamine, N-methylpipecolate, and piperidine that have been implicated in protection against colon cancer

Summary

Introduction

Dry beans are staple foods and well recognized sources of vital macronutrients [1] and micronutrients such as folate, iron and magnesium [2]. Among the 17 grain legumes identified as food sources by the Food and Agriculture Organization of the United Nations, common bean (Phaseolus vulgaris L.) are among the most widely produced. There are economic, health and environmental arguments for increasing the consumption of common beans as a primary source of dietary protein and fiber in the diet. Additional attention is needed towards the functional properties of beans in Western diets that may reduce risk for major chronic diseases [3]. U.S.A was reported to be very low and approximately 58–65% of adults were below the recommended levels of intake [4,5,6,7,8].

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Discussion

Conclusion