[Endogenous synthesis of carcinogenic N-nitroso compounds: bacterial flora and nitrite formation in the healthy human stomach].

The endogenous synthesis of cancerogenic N-nitroso compounds: Bacterial flora and nitrite formation in the human stomach. In the discussion of the endogenous nitrosamine synthesis, nitrites play a decisive role. Since in a healthy stomach the acidity important for the nitrosamine formation is present, but since this acid environment is hostile to the bacterial growth and thus counteracts bacterial endogenous nitrite formation, the oral cavity has so far been regarded as the main site of endogenous nitrite formation. An analysis of 130 gastric secretions taken from empty stomachs has demonstrated that also in a healthy stomach considerable germ counts may be obtained in part when acidity is lowered physiologically (e.g. at night). Nitrite concentrations, which are six times as high as the quantities supplied with the saliva at the same time, are also produced in the acid pH range from 4 to 6. Consequently, in a healthy stomach as well the quantity of nitrite available for an endogenous nitrosamine synthesis is by far higher than has been assumed previously. This physiological risk should be allowed for in evaluating the pathophysiological or therapeutic changes in the gastric environment.