It has been shown by Newburgh and his collaborators1 (1919, 1923) that high protein diets produce renal injury in rabbits, and by Polvogt, McCollum and Simmonds2 (1923) that similar diets have a harmful effect on the kidneys of rats. In explanation of this fact, a number of possibilities present themselves for consideration, among which are: (1) poisonous products arising from the action of bacteria on the food in the intestine; (2) the absorption of foreign protein forced into the blood by the excess in the intestine; (3) the excretion of an acid urine from diets high in certain proteins; (4) extra work required of the kidney by the increased nitrogen metabolism, and (5) lack of vitamins. No evidence in favor of any of these explanations was obtained.
In a previous article, it was suggested that the amino-acids themselves might be the source of the renal injury. That both the absorption