Summary - Nitrites (E249-250)
E249: Potassium nitrite (KNO2)
E250: Sodium nitrite (NaNO2)
Nitrites are used in order to inhibit the growth of microorganisms such as Clostridium botulinum spores in refrigerated meats and thereby reduce the formation of botulism but are also used as an antioxidant to decrease lipid oxidation in food.
Nitrates occur naturally in the environment, in mineral deposits, soil, seawater, freshwater systems, and the atmosphere. Nitrate and nitrite are commonly used as preservatives and for colour enhancement of processed meats, although the amounts added to these products have been substantially reduced from the levels once used.
Vegetables are the major source of dietary nitrate, with wide variations in nitrate content, particularly spinach, celery, beets, lettuce, and root vegetables.
The body also makes approximately 62 mg/day of nitrate in addition to what is ingested. Infection and illness can cause the body to produce even greater levels of nitrate (1).
The presence of nitrate in vegetables is often associated with harmful effects on human health and the possibility of causing an endogenous formation of carcinogenic N-nitroso compounds. However, it is also associated with beneficial health effects, since nitrate represent an important alternative pathway to bioactive NO and its important physiological roles in vascular and immune function (2).
The Romans laid the basis for meat fermentation and probably discovered the reddening effect of curing salt, which has later been attributed to nitrogen monoxide formation from nitrite. Specific colour development results from interactions between the myoglobin of the meat and nitrogen monoxide, originating from the nitrate and/or nitrite in the curing salt (3).
Nitrite (and its precursor nitrate), in curing salt have been identified as a precursor of carcinogenic nitrosamines (3). This resulted in the classification of cured meats as a potential public health hazard, leading to a worldwide scientific, public, and political debate that nearly caused the banning of nitrite in foods or the proposal to classify nitrite as a “developmental and reproductive toxicant“ (4). Nevertheless, the technological use of nitrite in fermented meat curing has been maintained, due to its crucial role in the development and stability of colour and flavour, as well as in the safeguarding from undesirable and pathogenic bacteria. Moreover, nitrosamine production in cured meats has been technologically minimized and the uptake of nitrate and nitrite from cured meats is almost negligible. Indeed, cured meats are only of minor importance regarding the uptake of nitrate, in comparison with plant-derived foods (70-90%) and drinking water (14%), and of nitrite, in comparison with human saliva (93%) (4). Even more strikingly, some researchers have suggested that nitrate and nitrite dietary supplementation may reduce certain cardiovascular risk factors or certain diseases characterized by nitrogen monoxide insufficiency (5).