Gastric cancer nitrosamines

As discussed in Section 13.3.6, ascorbate may act to inhibit the formation of carcinogenic nitrosamines from nitrite and dietary amines, and thus reduce the risk of cancer. There is some evidence that vitamin C supplements are protective against the development of gastric cancer. 

Fig. 18.2. Mutations in DNA caused by nitrosamines. Nitrosamines are consumed in many natural products and are produced in the stomach from nitrites used as preservatives and secondary amines found in foods such as fish. They are believed to be responsible for the high incidence of gastric cancer found in Japan and Iceland, where salt-preserved fish was a major dietary item. Nitrosamine metabolites methylate guanine (the transferred methyl group is shown in blue).

Hawksworth, G., Hill, M, J., Gordillo, G., and Cuello, C. (1975) Possible relationship between nitrates, nitrosamines and gastric cancer in South-West Colombia. "N-nitroso... 

Groenen PJ, de Cock-Bethbeder MW, Bouman J. et al. 1980. Formation of N-nitrosamines and N-nitrosamino acids from food products and nitrite under simulated gastric conditions. Proc of the Vlth Intern Symp on N-Nitroso Compounds International Agency for Research on Cancer (IARC) Lyon. 

Lu SH, Yang WX, Guo LP, et al. 1987. Determination of N-nitrosamines in gastric juice and urine and a comparison of endogenous formation of N-nitrosoproline and its inhibition in subjects from high-and low-risk areas for oesophageal cancer. lARC Sci Publ 84 538-543. 

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