Consequently, the addition of at least 550 ppm of ascorbic acid is required in meats manufactured in the United States. Manufacturers sometimes instead use erythorbic acid, a cheaper but equally effective isomer of ascorbic acid. Additionally, manufacturers may include α-tocopherol (vitamin E) to further inhibit nitrosamine production. α-Tocopherol, ascorbic acid, and erythorbic acid all inhibit nitrosamine production by their oxidation-reduction properties. Ascorbic acid, for example, forms dehydroascorbic acid when oxidized, which when in the presence of nitrosonium, a potent nitrosating agent formed from sodium nitrite, reduces the nitrosonium into nitric oxide. The nitrosonium ion formed in acidic nitrite solutions is commonly mislabeled nitrous anhydride, an unstable nitrogen oxide that cannot exist in vitro.Ingesting nitrite under conditions that result in endogenous nitrosation has been classified as "probably carcinogenic to humans" by International Agency for Research on Cancer (IARC).Sodium nitrite consumption has also been linked to the triggering of migraines in individuals who already experience them.One study has found a correlation between highly frequent ingestion of meats cured with pink salt and the COPD form of lung disease. The studys researchers suggest that the high amount of nitrites in the meats was responsible; however, the team did not prove the nitrite theory. Additionally, the study does not prove that nitrites or cured meat caused higher rates of COPD, merely a link. The researchers did adjust for many of COPDs risk factors, but they commented they cannot rule out all possible unmeasurable causes or risks for COPD.
For example, Parma ham, which has been produced without nitrite since 1993, was reported in 2018 to have caused no cases of botulism.Sodium nitrite has shown varying degrees of effectiveness for controlling growth of other spoilage or disease causing microorganisms. Although the inhibitory mechanisms are not well known, its effectiveness depends on several factors including residual nitrite level, pH, salt concentration, reductants present and iron content. The type of bacteria also affects sodium nitrites effectiveness. It is generally agreed that sodium nitrite is not effective for controlling Gram-negative enteric pathogens such as Salmonella and Escherichia coli.Other food additives (such as lactate and sorbate) provide similar protection against bacteria, but do not provide the desired pink color. Inhibition of lipid peroxidation
Sodium nitrite is also able to effectively delay the development of oxidative rancidity. Lipid peroxidation is considered to be a major reason for the deterioration of quality of meat products (rancidity and unappetizing flavors). Sodium nitrite acts as an antioxidant in a mechanism similar to the one responsible for the coloring effect. Nitrite reacts with heme proteins and metal ions, neutralizing free radicals by nitric oxide (one of its byproducts). Neutralization of these free radicals terminates the cycle of lipid oxidation that leads to rancidity. Medication
Sodium nitrite is used as a medication together with sodium thiosulfate to treat cyanide poisoning. It is recommended only in severe cases of cyanide poisoning. In those who have both cyanide poisoning and carbon monoxide poisoning sodium thiosulfate by itself is usually recommended.