Date of Award:

5-1969

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Committee Chair(s)

DeLoy G. Hendricks

Committee

DeLoy G. Hendricks

Committee

Ethelwyn B. Wilcox

Committee

Harris O. Van Orden

Abstract

A study was made of the adaptation to dietary protein of nitrogenous components in blood and urine of rats and humans. Forty-four mature male rats were adapted to a low protein diet (10 per cent casein diet) for three weeks before they were divided into two groups. Four rats were then killed for a control, and twenty of the remaining rats were switched to a high protein diet (40 per cent casein diet) and the other twenty continued to be fed the low protein diet. Four rats fed each level of protein were killed 2, 4, 6, 8, and 10 days after they were divided into two groups. A study similar to that carried out on rats was conducted on six male college students who were living in the same unit of a cooking dormitory. Blood and urine samples were taken when they were eating a normal diet as a control and then they were adapted on a low protein diet providing 12 per cent of the calories as protein for two weeks. They were then switched to a high protein diet containing 30 per cent protein calories for four consecutive days.

The rats fed the 40 per cent casein diet had a higher rate of weight gain and increased amounts of urine per 24 hours than the rats fed the 10 percent casein diet. Urinary output of the human subjects on the diets containing 30 per cent protein calories was greater than when they received the 12 per cent protein calorie diet.

There was a significant increase in total nitrogen and urea in serum and urine of rats and humans as the dietary protein level increased. The urinary excretion of uric acid, of creatinine in humans, and of urinary amino nitrogen and total serum protein in rats and humans were also increased appreciably as the protein intake increased. No significant effects or trends in serum amino nitrogen of humans, or serum creatinine in rats or humans were observed with the change in the level of dietary protein. The high casein diet fed to rats reduced the excretion of creatinine and serum uric acid, while the high meat intake increased the excretion of creatinine and of uric acid in the humans. It was also found that there was a high negative correlation between serum uric acid and urinary uric acid of rats, and between serum amino nitrogen and urinary amino nitrogen of human subjects.

This study indicates that the body rapidly adjusts to an altered level of protein intake by changing the level of nitrogenous components in blood and urine.

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