Safety Study of Dietary Nitrate in Humans: Carcinogenicity and Thyroid Function

Abstract

The nutritional nitrate is widespread in the human diet. The conventional approaches primarily view it as having possible health hazards, particularly in the formation of nitrosamines and cancer vulnerability. During the last twenty years, a body of evidence has slowly accumulated that demonstrates the beneficial effect of the nitrate to nitrite to nitric oxide pathway in the cardiovascular health. This route controls blood pressure and improves exercise performance making nitrate a dual-function molecule that has advantages and has the potential to be toxic. The other major challenge in the field today is the absence of an allinclusive risk-assessment framework. This framework must consider dose-response relations, exposure, and individual variation and the general dietary setup. Safe levels have not been defined in regard to people at risk like those with renal failure or those within thyroid disease susceptibility. Future studies should be able to define the extent and pathways of action of nitrate at two critical toxicological endpoints. The carcinogenicity and thyroid perturbation are these endpoints, and research must be conducted on modulatory responses of dietary habits and antioxidants. The current paper is a systematic review of the nitrate carcinogenicity, the mechanisms that may cause this carcinogenicity, and the influence on thyroid functioning. It is a summary of the available information to inform safety evaluation and health instructions of dietary nitrate.