ABSTRACT
Nitrite (NO2 -) and nitrate (NO3 -) are the storage pools for nitric oxide (NO)-like bioactivity, by complementing the NO synthase (NOS) dependent pathway. Although NO is one of the simplest biological molecules in nature, it is very important in almost every phase of biology and medicine. Continuous generation of NO is essential for the integrity of the cardiovascular system, and decreased production and/or bioavailability of NO leads to the development of many cardiovascular disorders. Three distinct NO synthase isoforms exist in mammals: inducible, neuronal, and endothelial. The two main sources of nitrate in the diet are vegetables and drinking water. Regardless of the source of exposure, the primary concern of exposure to nitrite, nitrate or other nitrogen oxides is the nitrosative chemistry that can occur. Despite the dietary nitrate beneficial effects on cardiovascular health (i.e., blood pressure reduction, improved endothelial function, protection against ischemia-reperfusion injury, mitigation of arterial stiffness, reduction of platelet activity, enhanced exercise performance), there is a concern among some researchers about the toxicity associated with intake of nitrate and nitrite, particularly in relation to methemoglobinemia, colorectal cancer, and cardiovascular disease.
