Nature has in it, several naturally occurring inorganic ions such as nitrates and nitrites. These are important forms present as a part of the nitrogen cycle. A small fraction of nitrates naturally occurs in the human body, while the body is otherwise exposed to nitrates and nitrites through air, water, and soil, primarily being carried or spread from fertilizers that contain nitrates and nitrites. Hence, when eating or drinking water from areas where nitrogen-containing fertilizers are put to high use, the exposure to such ions can be considerably high.
Roots, green leafy vegetables, and certain other vegetables, like cauliflower and broccoli demand high nitrogen-containing fertilizer quantities for their growth. Apart from this certain medications are said to be high in nitrates, especially inhalants that give out nitrite fumes and may be an etiology to hypotension.
How does the exposure pose a health risk? Nitrites and nitrates on excessive exposure can render hemoglobin inactive or weakened by altering hemoglobin’s iron state that causes iron bonding to turn unstable. As a result “met-hemoglobin” is formed that has a comparatively reduced oxygen-carrying capacity. Oxygen supply to the body tissues may be resultantly low and the body may experience a state of anoxia. Accumulation of this met-hemoglobin, known as “met-hemoglobinemia” causes symptoms similar to that of anemia as both conditions are characterized by reduced or altered iron in the hemoglobin base structure. Initially blue skin coloration (cyanosis), reduced heart rate, and generalized weakness, are manifested; however, in severe cases the victim may face shortness of breath, lack of concentration, headaches and dizziness, lethargy, fatigue, breathing difficulties, convulsions, shocks, and move into a state of coma.
In fact, a 1977 clinical study conducted by Nathan and co-authors discovered that a met-hemoglobin blood level exceeding over 50% can prove to be fatal. Other causatives to raise met-hemoglobin in blood could be consumption of oxidizing drugs or inhaling such chemicals, abnormal increase in fluid acidity or a fluid imbalance through conditions, like vomiting and diarrhea.
Rarely, an inherited genetic disorder as in the case of infant cyanosis could also lead to met-hemoglobinemia. Hence, maternal exposure to nitrites and nitrates during the pregnancy period may lead to serious pregnancy-associated complications. Since the blood volume nearly doubles during the pregnancy phase, iron levels are already difficult to cope with which is why met-hemoglobin formation can further worsen the condition. Infants under four months of age are vulnerable to developing met-hemoglobinemia due to the high alkaline nature of their gastrointestinal tract that supports nitrate-reducing organisms as some bacteria types.
Additionally, it also found that nitrites possess the ability to enter a certain metabolic pathway physiologically that may lead to nitrites reacting with specific molecules to form N-nitroso conjunctions that are found to be carcinogenic. However, the Environmental Protection Agency and International Agency of Research on Cancer do not classify nitrites or nitrates as cancer-causing ions. The only way to detect nitrates or nitrites is through blood examinations for met-hemoglobin levels.
However, nitrites and nitrates are credited for benefiting cardiac health and output by various studies. One such study conducted in 2011 by Tanq and co-authors has attempted to review a wide range of published literature to assess outcomes of nitrate and nitrite exposures to portray associated health risks, as well as benefits that stated that cancer developing risks are low. On the other hand nitrites and nitrates in a few foods can be converted to nitric oxide that largely benefits cardiovascular wellness. As per another study by Hord conducted in 2011, the substance nitric oxide is formed as a result of UV exposure of the skin and the function of synthesizing and reducing enzymes of nitrites and nitrates in the body. The study also describes how nitric oxide benefits the heart; dietary nitrates and nitrites are said to be antiplatelet, hypotensive, and cytoprotective.
Another significant point to note is that cancers are a concern in case of these ions, when consumption of certain foods like roots, cauliflowers or soya milk is extremely regular.