The Influence of High and Low Protein Diets on Blood Chemistry. ∗

Abstract

This paper is part of an investigation of the influence of high and low protein diets on basal metabolism, blood chemistry, and the urinary nitrogenous compounds. For a period of 37 days 6 apparently normal women, all engaged in laboratory work, received a high protein diet containing 2 gm. of protein and sufficient carbohydrate and fat to make 40 calories per kilo of body weight. An interval of 3 weeks was then allowed in which the protein intake was lowered until it reached 0.5 gm. per kilo. Although the carbohydrate and fat intake on the low protein diet was adjusted so that the caloric value of the two diets remained the same, all subjects lost weight during the first 10 days. The protein value was then increased to 0.6 gm. per kilo and the weight remained stationary. The low protein diet was continued for 30 days.

All foods were carefully weighed. On 4 days of each week basal metabolism was taken, specimens of blood and urine were collected, and samples of foods were saved and analyzed. Blood was drawn from the cubital vein without turniquet before breakfast, after 30 minutes rest, and was analyzed for sugar, total non-protein nitrogen, urea nitrogen, creatine, creatinine, uric acid, and lactic acid. Total non-protein nitrogen was determined by Koch's method and lactic acid by Clausen's procedure modified by Friedemann. Folin's methods were used for all the other constituents. All determinations were made in duplicate.

No consistent differences were found in blood sugar levels on the two diets. In 3 subjects the blood sugar showed a rise on the low protein diet, but in the other 3 it remained the same on both diets. The average figures for 6 subjects for the 5 weeks on the high protein diet ranged between 86.9 and 80.9 mg. per 100 cc. of blood, while the corresponding values for the low protein diet were 91.6 and 83.5.