Saltpeter is the best known nitrite with its undeserved reputation as the sex-drive inhibitor. Nitrites also occur naturally in foods. The chief concern is the ability of nitrites to combine with amino acids in GIT to form nitrosamine s, potentially carcinogenic molecules. Vitamin C inhibits nitrosamine formation and is thought to protect against GIT cancer. Vitamin C is an antioxidant preservative, and can replace less desirable preservatives in some foods.
Tobacco smoke is the major source of human exposure to nitrosamines.
Salicylates Salicylates are common in vegetables and fruit. Medicinal salicylates came from plant sources such as willow-bark methylsalicylate. As oil of wintergreen, methylsalicylate has been rubbed on many cold-stricken chests and inhaled by coughing children for many years. ASA is an effective drug, with diverse benefits, but it routinely causes GIT irritation and bleeding. It is a good allergen and causes many rashes and hives.