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The Availability of Ascorbic Acid in Papayas and Guavas¹

Two Figures

Nutritional Department, Hawaii Agricultural Experiment Station, Honolulu, Hawaii

The availability of the ascorbic acid of papayas and guava juice was determined by comparing the urinary excretion of ascorbic acid by human subjects maintained on a diet low in ascorbic acid: (a) when receiving 75 mg. of synthetic ascorbic acid per day; and (b), when receiving an equivalent amount of ascorbic acid in the form of papayas or guava juice. Two experiments involving a total of fourteen subjects (eight men and six women) were carried out.

The two experiments differed from each other only in the way in which the experimental periods were divided. In the first experiment 6-day periods preceded by a 1-day saturation period were used. In the second experiment the subjects remained continuously on the basal diet plus 75 mg. of ascorbic acid for 5 weeks, the first 2 weeks serving as a preliminary adjustment period and only the last 3 weeks being used for purposes of comparison. This latter procedure greatly reduced the variation in the data obtained.

No significant differences in the availability of the ascorbic acid of papayas or guava juice as compared with synthetic ascorbic acid were found in either experiment.

Blood plasma ascorbic acid levels which were determined in experiment II were similar in all experimental periods. Subjects receiving 75 to 80 mg. of ascorbic acid per day over a period of 5 weeks maintained plasma levels of from 0.7 to 1.0 mg. %.

In some instances menstruation appeared to have a depressing effect on the excretion of ascorbic acid.

Manuscript received 22 March 1945.