Endogenous N-nitrosation in man assessed by measurement of apparent total N-nitroso compounds in faeces

Carcinogenesis. 1991 Aug;12(8):1395-401. doi: 10.1093/carcin/12.8.1395.


The faecal concentration of substances responding to the chemical test for N-nitroso compounds (apparent total N-nitroso compounds, ATNC) was investigated in human subjects consuming their normal free-choice diet. Concentrations ranged from 40 to 590 micrograms (N-NO)/kg faeces. To ascertain the likely relative contributions of endogenous ATNC formation and preformed, dietary ATNC, the subjects consumed a diet low in nitrate and ATNC for 8 days. At the end of this period, ATNC had decreased substantially with concentrations ranging from below the 40 micrograms (N-NO)/kg detection limit up to 143 micrograms (N-NO)/kg, mean 82 micrograms (N-NO)/kg. On supplementing this diet with 300 mg nitrate/day, faecal ATNC levels increased markedly. On the third day of this regime, values were in the range 73-714 micrograms (N-NO)/kg with a mean of 307 micrograms (N-NO)/kg. The results, together with the known limited occurrence of ATNC in the majority of foodstuffs so far tested, generally non-detectable or less than 100 micrograms (N-NO)/kg, suggest that endogenous formation via species derived from dietary nitrate is likely to be an important source of ATNC in human faeces.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Diet
  • Feces / chemistry*
  • Female
  • Humans
  • Male
  • Nitrates / administration & dosage
  • Nitrates / metabolism
  • Nitrosation
  • Nitroso Compounds / analysis
  • Nitroso Compounds / metabolism*
  • Nitroso Compounds / pharmacokinetics
  • Sex Factors


  • Nitrates
  • Nitroso Compounds