Bethesda, MD
Description
The National Heart, Lung, and Blood Institute convened this workshop to discuss the results of recent research on the effects of inorganic nitrate and nitrite on the cardiovascular system, possible long term effects of these compounds in the diet and drinking water, and future research needs including population-wide effects examined through epidemiological studies.
Background:
Research in the past decade has demonstrated that the body can use exogenous nitrite and nitrate to produce the important messenger molecule, nitric oxide. In small feeding trials, ingested nitrate is absorbed with great efficiency, after which some of it is reduced to nitrite by enterosalivary cycling. Nitrite is then available as a circulating storage pool for nitric oxide bioactivity. Subsequent reduction of nitrite to nitric oxide takes place in many tissues, particularly under conditions of hypoxia, resulting in vasodilation and platelet inhibition, and the enhancement of oxidative metabolic efficiency, among other functions.
It is possible that the cardiovascular protective effect of a diet rich in fruits and vegetables is in part due to its high nitrate content, contributed largely by leafy green vegetables and root vegetables. In an attempt to exploit the cardiovascular benefits of nitrate for the benefit of athletic performance, there has been a recent rapid proliferation of unregulated performance-enhancing supplements containing high amounts of nitrate. However, in contrast to a likely salutary role played by dietary nitrate and nitrite in cardiovascular health, there is a long history of research on a possible deleterious role of nitrate and nitrite in food and of nitrate in drinking water with the endogenous production of carcinogenic N-nitroso compounds.
To address the current state of our knowledge of the exposure and effects of dietary nitrate, we convened this working group of investigators in nitrate physiology; nitrate distribution in groundwater, soils, plants, and dietary components; cancer epidemiology; and cardiovascular disease epidemiology.