herring meal that was preserved using sodium nitrite. The sodium nitrite had reacted with dimethylamine in the fish and produced dimethylnitrosamine, which was determined to be carcinogenic during the studies of the 1950s. Opposing reactions with ascorbic acid Endogenous nitrosamine formation can be affected by ascorbic acid, either inhibiting its formation or increasing its formation, depending upon whether ascorbic acid is consumed in conjunction with it as opposed to the effect being reversed by factors related to dietary fat consumed at the same time. In the case of formation of carcinogenic nitrosamines in the stomach from dietary nitrite (used as a processed meat preservative), ascorbic acid markedly decreases nitrosamine formation in the absence of fat in the meal, through inhibition. However, when 10% of the meal is fat, the effect is reversed, such that ascorbic acid then markedly increases nitrosamine formation. A yeast study has shown that N-nitrosamines can perturb amino acid metabolism and mitochondrial function. Examples See also Angiotensin II receptor blocker recalls Hydrazines derived from these nitrosamines, e.g. UDMH, are also carcinogenic. Possible health hazards of pickled vegetables Ranitidine cancer-causing impurities Tobacco-specific nitrosamines Valsartan recalls Additional reading References External links Oregon State University, Linus Pauling Institute article on Nitrosamines and cancer, including info on history of meat laws Risk factors in Pancreatic Cancer Nitrogen cycle Functional groups Garde manger Carcinogens IARC Group 1 carcinogens