The Effects of Dietary Nitrate on Rabbits and Rats

Methemoglobin rises significantly in the circulation of rabbits and rats with increases in the levels of nitrate ingested either as sodium nitrate or as it occurs naturally in plant food. The levels to which methemoglobin rises are not high enough to cause abnormal behavior or appearance except in occasional animals temporarily aberrant due to unexplained causes, or in a larger number of animals ingesting amounts of nitrate greater than would likely occur under natural conditions. The fact that large amounts of nitrate ingested cannot be recovered in that form in the excreta permits the assumption that some of it is reduced in the body. The recovery of small amounts of nitrite in the urine substantiates this assumption and provides evidence for its existence in the blood where it could act on the hemoglobin. Some nitrate remains unaccounted for and this raises the question of its fate and the reaction in the system of any other products which might be formed.