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The Sparing Action of Protein on the Pantothenic Acid Requirement of the Rat

II. Urinary and Fecal Excretion of Pantothenic Acid¹

Two Figures

Institute of Experimental Biology, University of California, Berkeley

Studies of urinary and fecal excretion of pantothenic acid by deficient rats maintained on purified diets differing in casein level gave the following results:

1. Urinary pantothenic acid excretion was significantly higher on diets containing 64% casein than on diets containing 24% casein and paralleled the increased growth and survival observed at the higher protein level. Urinary excretion increased with age on the 64% casein diet.

2. Fecal pantothenic acid excretion was higher when rats were fed than when they were fasted and was notable for its variability. During the first 90 days there was no significant difference in fecal excretion, regardless of the casein level. With increasing age and body weight there was a tendency for fecal output to increase on the higher protein level.

3. When intermediate levels of casein were used, growth, survival and urinary pantothenic acid (but not fecal pantothenic acid) were proportional to the casein level.

4. When low levels of pantothenic acid equivalent to that present in the high casein diets (by microbiological assay) were added to the 24% casein diet, growth and urinary pantothenic acid were not equal to those observed on the higher casein diets. When approximately double the equivalent amount of pantothenic acid was added to the 24% casein diets, the results were equivalent to those observed at the 44% casein level but were still not equal to those at the 64% casein level.

Neither increased intestinal synthesis of pantothenic acid as measured by fecal excretion nor a decreased vitamin loss by urinary excretion are responsible for the sparing action of high casein diets on the pantothenic acid requirement of the rat. The pantothenic acid content of the casein used in the purified diet while exercising an effect can not fully account for the protective action of such diets.

² General Mills Fellow.

Manuscript received 5 March 1947.