title: Reevaluation of nitrate and nitrite levels in the human intestine.
abstract: Analyses of human fecal and ileostomy samples by a method that is insensitive and free from interferences indicate that nitrate and nitrite levels in the intestine are lower than reported previously. Fecal nitrate and nitrite concentrations ranged from 0 to 14 mumol/kg (0 to 0.9 ppm) and 5 to 19 mumol/kg (0.3 to 0.9 ppm), respectively. Ileostomy samples contained from 0 to 7 mumol/kg (0 to 0.4 ppm) and 0 to 15 mumol/kg (0 to 0.7 ppm) for nitrate and nitrite, respectively. We also showed that, when deliberately added to feces samples, nitrate and nitrite were destroyed during a two-hr incubation period in a reaction that depended on the presence of microorganisms. The results suggest that conditions in the lower gastrointestinal tract favor denitrification, not nitrification as had been proposed previously.
mesh_terms: D000293:Adolescent; D000328:Adult; D000332:Aerobiosis; D000693:Anaerobiosis; D005243:Feces / Q000032:analysis*; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008722:Methods; D008875:Middle Aged; D009566:Nitrates / Q000032:analysis* / Q000378:metabolism; D009573:Nitrites / Q000032:analysis* / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D009566:Nitrates; D009573:Nitrites