Tolerance Curve of Vitamin C ∗

Abstract

The suggestion has been made that intravenous injection of vitamin C, preoperatively, might be of value in preventing the resultant traumatic shock. 1-3 Oral administration has a more prolonged effect upon the blood ascorbic acid concentration and results in greater retention of the vitamin. 4-9 This study was made in an attempt to determine the quantity of synthetic ascorbic acid which, on ingestion, would produce a high concentration of the vitamin in the blood plasma and maintain an increase for a relatively long period of time.

The results of 80 tolerance curves are herein reported. With a lapse of at least one week between each observation, 12 young college women were given 250, 500, 750 and 1000 mg of ascorbic acid, orally. All tests began early in the morning, with omission of breakfast. Lunch was limited, consisting only of vitamin C-free foods. Fasting bloods were taken just before ingestion of the test dose, and subsequent blood samples were drawn each hour thereafter for 6 to 10 hours, depending upon the amount of synthetic vitamin given. Determination of the vitamin C content of the blood plasma was made by the Farmer-Abt micro-method. 10

The 80 fasting values thus obtained ranged from 0.36 mg to 1.36 mg of ascorbic acid per 100 cc of plasma, the average concentration being 0.79 nig %. During the 3-month period the fasting values changed very little for any individual. The response to a test dose varied from subject, but neither the amount of increase in plasma ascorbic acid concentration not its duration were directly related to the concentration of the vitamin in the fasting sample. Tolerance curves of subjects with the lower initial blood plasma levels showed as much rise above fasting as those in which the initial values were higher.