In biochemistry,

nitrosamines Nitrosamines (or more formally ''N''-nitrosamines) are organic compounds produced by industrial processes. The chemical structure is , where R is usually an alkyl group. Nitrosamines have a nitroso group () that are "probable human carcinogens", ...

are a class of compounds that can form during

food Food is any substance consumed by an organism for Nutrient, nutritional support. Food is usually of plant, animal, or Fungus, fungal origin and contains essential nutrients such as carbohydrates, fats, protein (nutrient), proteins, vitamins, ...

digestion Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into th ...

. The presence of their precursors,

nitrite The nitrite polyatomic ion, ion has the chemical formula . Nitrite (mostly sodium nitrite) is widely used throughout chemical and pharmaceutical industries. The nitrite anion is a pervasive intermediate in the nitrogen cycle in nature. The name ...

s, in

cured meat Curing is any of various food preservation and flavoring processes of foods such as meat, fish and vegetables, by the addition of salt, with the aim of drawing moisture out of the food by the process of osmosis. Because curing increases the solu ...

s, is controversial, because of a small connection to cancer risk.

Background

Nitroso In organic chemistry, nitroso refers to a functional group in which the nitric oxide () group is attached to an organic moiety. As such, various nitroso groups can be categorized as ''C''-nitroso compounds (e.g., nitrosoalkanes; ), ''S''-nitros ...

compounds react with

primary amine In chemistry, amines (, ) are organic compounds that contain carbon-nitrogen bonds. Amines are formed when one or more hydrogen atoms in ammonia are replaced by alkyl or aryl groups. The nitrogen atom in an amine possesses a lone pair of elec ...

s in acidic environments to form

nitrosamine Nitrosamines (or more formally ''N''-nitrosamines) are organic compounds produced by industrial processes. The chemical structure is , where R is usually an alkyl group. Nitrosamines have a nitroso group () that are "probable human carcinogens", ...

s, which human metabolism converts to mutagenic

diazo compound In organic chemistry, the diazo group is an organic moiety consisting of two linked nitrogen atoms at the terminal position. Overall charge-neutral organic compounds containing the diazo group bound to a carbon atom are called diazo compounds ...

s. Small amounts of nitro and nitroso compounds form during meat curing; the toxicity of these compounds

preserves Fruit preserves are preparations of fruits whose main preserving agent is sugar and sometimes acid, often stored in glass jars and used as a condiment or spread. There are many varieties of fruit preserves globally, distinguished by the meth ...

the meat against

bacterial infection Pathogenic bacteria are bacteria that can cause disease. This article focuses on the bacteria that are pathogenic to humans. Most species of bacteria are harmless and many are beneficial but others can cause infectious diseases. The number of t ...

. After curing completes, the concentration of these compounds appears to degrade over time. Their presence in finished products has been tightly regulated since several food-poisoning cases in the early 20th century, but consumption of large quantities of processed meats can still cause a slight elevation in

gastric The stomach is a muscular, hollow organ in the upper gastrointestinal tract of humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical terms re ...

and

oesophageal cancer Esophageal cancer (American English) or oesophageal cancer (British English) is cancer arising from the esophagus—the food pipe that runs between the throat and the stomach. Symptoms often include difficulty in swallowing and weight loss. Ot ...

risk today. For example, during the 1970s, certain Norwegian farm animals began exhibiting elevated levels of

liver cancer Liver cancer, also known as hepatic cancer, primary hepatic cancer, or primary hepatic malignancy, is cancer that starts in the liver. Liver cancer can be primary in which the cancer starts in the liver, or it can be liver metastasis, or secondar ...

. These animals had been fed

herring Herring are various species of forage fish, belonging to the Order (biology), order Clupeiformes. Herring often move in large Shoaling and schooling, schools around fishing banks and near the coast, found particularly in shallow, temperate wate ...

meal A meal is an occasion that takes place at a certain time and includes consumption of food. The English names used for specific meals vary, depending on the speaker's culture, the time of day, or the size of the meal. A meal is different from a ...

preserved with

sodium nitrite Sodium nitrite is an inorganic compound with the chemical formula . It is a white to slightly yellowish crystalline powder that is very soluble in water and is hygroscopic. From an industrial perspective, it is the most important nitrite sa ...

. The sodium nitrite had reacted with

dimethylamine Dimethylamine is an organic compound with the formula (CH3)2NH. This secondary amine is a colorless, flammable gas with an ammonia-like odor. Dimethylamine is commonly encountered commercially as a solution in water at concentrations up to around ...

in the fish and produced

dimethylnitrosamine ''N''-Nitrosodimethylamine (NDMA), also known as dimethylnitrosamine (DMN), is an organic compound with the formula (CH3)2NNO. It is one of the simplest members of a large class of nitrosamines. It is a volatile yellow oil. NDMA has attracted wi ...

. The effects of nitroso compounds vary dramatically across the gastrointestinal tract, and with diet. Nitroso compounds present in stool do not induce nitrosamine formation, because stool has neutral pH.

Stomach acid Gastric acid or stomach acid is the acidic component – hydrochloric acid – of gastric juice, produced by parietal cells in the gastric glands of the stomach lining. In humans, the pH is between one and three, much lower than most other an ...

catalyzes nitrosamine compound formation and is the main location of the reaction during digestion. The formation process is inhibited when amine concentration is low (e.g. a low-protein diet or no fermented food). The process may also be inhibited in the case of high vitamin C (ascorbic acid) or

erythorbic acid Erythorbic acid (isoascorbic acid, D-araboascorbic acid) is a stereoisomer (C5 epimer) of ascorbic acid (vitamin C). It is synthesized by a reaction between methyl 2-keto-D-gluconate and sodium methoxide. It can also be synthesized from sucrose or ...

concentration (e.g. high-fruit diet). However, when 10% of the meal is fat, the effect reverses, and ascorbic acid markedly increases nitrosamine formation. Vitamin C and erythorbic acid are already commonly used in the meat industry because they enhance the binding of nitrite to myoglobin, encouraging the formation of the desired pink color.{{cite journal , last1=Pappenberger , first1=Günter , last2=Hohmann , first2=Hans-Peter , title=Industrial Production of l-Ascorbic Acid (Vitamin C) and d-Isoascorbic Acid , journal=Biotechnology of Food and Feed Additives , date=2013 , volume=143 , pages=143–188 , doi=10.1007/10_2013_243

References

Digestive system Nitrosamines