Plain language summary
Colorectal cancer (CRC) is one of the leading cause of cancer-related death around the world. Emerging evidence supports that increased consumption of pulses / legumes, such as navy beans, can reduce risk. Consuming navy beans as part of one's diet has been previously shown to positively affect the relationship between a person's gut bacteria and their health status. This study looked at stool samples to assess the impact of navy bean consumption on health based on the by-products of metabolism generated by gut bacteria (metabolites). The study was a 4-week, randomised-controlled trial with overweight and obese CRC survivors and involved consumption of 1 meal and 1 snack daily. People in the intervention group ate 35g of cooked navy bean daily whereas those in the control group had 0g of navy beans. From amongst the hundreds of metabolites identified in both groups, there was a 5-fold increase in ophthalmate for navy bean consumers, which can indicate an increase in glutathione. Glutathione is an antioxidant and detoxifying substance produced in the human liver. It is involved in cancer control mechanisms such as detoxification of xenobiotics (toxins), antioxidant defense, proliferation, and apoptosis. Other interesting results include the metabolism of the amino acid lysine, which supports health immune function, and an increase in plant-based nutrients or phytochemicals in those who consumed navy bean vs the control group. These results are indicative of an acute response to increased navy bean intake, which merit further investigation for improving colonic health after long-term consumption.
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.
Methodological quality
Jadad score
:
5
Allocation concealment
:
Yes
