Geographic distribution of liver and stomach cancers in Thailand in relation to estimated dietary intake of nitrate, nitrite, and nitrosodimethylamine.

It is our working hypothesis that the high rate of the liver and gastric cancers in North and Northeast Thailand is associated with increased daily dietary intake of nitrate, nitrite, and nitrosodimethylamine (NDMA). Samples of fresh and preserved Thai foods were systematically collected and analyzed from 1988 to 1996 and from 1998 to 2005. Consumption frequencies of various food items were determined on the basis of a dietary questionnaire given to 467 adults (212 males and 255 females) from 1998 to 2005.