Dietary influence on some proposed risk factors for colon cancer: Fecal and urinary mutagenic activity and the activity of some intestinal bacterial enzymes

This investigation studied the effects of a shift from a well-balanced mixed diet to a lactovegetarian diet on the mutagenic activity in urine and feces and on some cancer-associated bacterial enzymes in human feces (β-glucuronidase, β-glucosidase, and sulphatase). Three months after the shift to the lactovegetarian diet, there was a significant decrease in mutagenic activity in urine and feces. β-glucuronidase, β-glucosidase, and sulphatase per gram feces wet weight. In contrast, the fecal mutagenic activity and the enzyme activities remained unchanged if expressed per daily output. However, the urinary mutagenic activity expressed as total daily output decreased. Part of the explanation for the decreased fecal mutagenic activity and the decreased enzyme activities is obviously a dilution effect, because much of the increased fecal weight after the shift in diet was associated with a higher water content.