Blood Plasma Ascorbic Acid Values Resulting from Normally Encountered Intakes of this Vitamin and Indicated Human Requirements

Abstract

A study of daily ascorbic acid requirements of the normal human adult has been made on twelve subjects on controlled, normally encountered ascorbic acid intakes of 32 to 110 mg., gradually increased without interruption by large test doses, over periods of 8 and 10 weeks. The subjects were brought into equilibrium or slight deficiency as shown by plasma ascorbic acid averages which were slowly decreasing or only maintaining themselves. This was accomplished by an initial period on a 32- to 35-mg. intake of ascorbic acid. Weekly averages of daily plasma ascorbic acid values gave a better reflection of the vitamin status of the individual than single determinations. Trends thus established showed the dynamic status of the individual with respect to intake. Urinary excretion studies were made on three subjects for a 30-day period. “Utilization” values were shown to be close to 1 mg. per kilogram body weight. An intake of 1 mg. per kilogram of body weight was shown to increase plasma ascorbic acid values for all subjects studied and three subjects were shown to reach saturation on such a retention.