Nitrosamines are formed in acidic conditions, such as those afforded by stomach acid, but vitamin C inhibits their formation, by converting nitrite to nitric oxide.

• 亚硝酸盐存在于人类的唾液和某些特定食物保护剂中，它们能转化为致癌物质亚硝胺。亚硝胺主要在酸性环境中形成，例如胃酸条件下。