Evidence that ingested nitrate and nitrite are beneficial to health.

The literature was reviewed to determine whether ingested nitrate or nitrite may be detrimental or beneficial to human health. Nitrate is ingested when vegetables are consumed. Nitrite, nitrate's metabolite, has a long history of use as a food additive, particularly in cured meat products. Nitrite has been a valuable antibotulinal agent in cured meats and may offer some protection from other pathogens in these products as well. Nitrite's use in food has been clouded by suspicions that nitrite could react with amines in the gastric acid and form carcinogenic nitrosamines, leading to various cancers. Nitrate's safety has also been questioned, particularly with regard to several cancers. Recently, and for related reasons, nitrite became a suspected developmental toxicant. A substantial body of epidemiological evidence and evidence from chronic feeding studies conducted by the National Toxicology Program refute the suspicions of detrimental effects. Recent studies demonstrate that nitrite, upon its ingestion and mixture with gastric acid, is a potent bacteriostatic and/or bactericidal agent and that ingested nitrate is responsible for much of the ingested nitrite. Acidified nitrite has been shown to be bactericidal for gastrointestinal, oral, and skin pathogenic bacteria. Although these are in vitro studies, the possibility is raised that nitrite, in synergy with acid in the stomach, mouth, or skin, may be an element of innate immunity.