Population-based cohort study of the association of nitrate and nitrite intake with risk of colorectal cancer

Dietary nitrate and nitrite exposure can generate N-nitroso compounds, some of which are known animal carcinogens. A population-based cohort study in Sweden evaluated the association of dietary nitrate and nitrite intake with the risk of colorectal cancer (CRC). Nitrate and nitrite intake was assessed by linking a food and drinking water database to food frequency questionnaires completed in 1997 and updated in 2009 and 2019 by 82,009 middle-aged to elderly men and women. Incidental CRC was ascertained through the Swedish Cancer Registry from 1998 to 2022. A total of 3170 CRC cases were ascertained. There were no associations for nitrate intake with CRC. In contrast, when comparing the highest to the lowest quintile, nitrite intake was associated with a dose-dependent higher risk of CRC in men (HR 1.23; 95% CI 1.06-1.45) but not in women. CRC subsite analyses in men indicated the strongest association for distal colon cancer (HR 1.50; 95% CI 1.13-1.98). The authors conclude that a higher nitrite intake was associated with a higher CRC risk, particularly distal colon cancer, in men but not in women.