Abstract
Five female subjects were given four types of test diets containing various levels of protein for four consecutive 5-day periods and their dietary fiber and feces were collected throughout the experimental period. Diet A was a high-fiber, low-protein diet containing brown rice. Diet B was a semi-purified, low-protein diet containing agar agar as the sole source of dietary fiber. Diet C was a low-fiber, normal-protein diet containing polished rice. Diet D was a high-fiber, normal-protein diet containing brown rice. A fecal marker was given at breakfast on the first day of each five-day test period and on the day after the end of the experiment.
Fecal weight increased during the period on high-fiber diets (diets A and D). The apparent digestibilities of protein and fat were significantly depressed by high-fiber diet. Fecal excretion of calcium did not increase on the high-fiber diets. A decrease in the apparent digestibility on a high-fiber, low-protein diet was partly due to the low intake of calcium during this period. Fecal excretion of cholesterol increased markedly during the periods on high-fiber diets. The difference between the intake and fecal excretion of dietary fiber suggested that the fiber was partially digested in the colon.
