Plasma Nitrate and Nitrite as Biological Indicators of Health and Disease in Nutritional Studies

Abstract

Dietary vegetables represent a nitrate-rich source for humans, and consumption increases plasma levels of nitrate two- to threefold. Both dietary nitrates and nitrites can also be bioactivated endogenously to form NO and other nitrated bioactive molecules. The relative critical importance of NO and its vasodilatory function, among many others, have garnered considerable research interest. Research efforts to monitor NO formation and correlate with potential beneficial health outcomes are hindered by the extremely fast half-life of NO. However, the immediate metabolic byproducts of NO formation are nitrate and nitrite. Given the considerable stability of the former, it has been used routinely and effectively in nutritional studies as a surrogate biomarker, although indirect, for NO production. From these studies, dietary nitrates and purportedly NO have been correlated with myriad beneficial health outcomes in nutritional studies. Further investigation is needed regarding physiological functions and therapeutic applications of dietary nitrates with a focus on large epidemiological studies.