Effect of Long-term Mega Vitamin C Ingestion on the Blood Ascorbic acid Concentration in Man

Daily 1gm of ascorbic acid was administered to 5 healthy adult volunteers who had not been taking any vitamin preperations for at least 2 months prior to present study. Periodical determination of plasma and RBC ascorbic acid concentrations were carried out throughout 9 weeks of administration and afrer cessation of ascorbic acid. Mean baseline (0 day) ascorbic acid concentrations were low normal (4.416±1.03ug/ml) in plasma and 4.05±1.14ug/10¹⁰RBC. Plasma concentrations were raised and remained higher throughout 9 weeks and slowly returned to baseline level after cessation of ingestion. According to baseline plasma ascorbic acid concentrations and reponses to vitamin C administrations, subjects were divided into suboptimal (1.55-2.4ug/ml) and normal (6-8ug/ml) group. After rise of concentrations in RBC, there was decreasing tendency in spite of continous ingestion of ascorbic acid. Blood concentrations of suboptimal group responded more rapidly and in greater rates than that of normal group. At 7 weeks RBC concentrations of normal group were decrease below baseline and did not return to baseline until 2 weeks after cessation of ascorbic acid ingestion. Therefore it is concluded that routine or habitual long-term ingestion of Mega Vitamin C is not desirable. Whenever it is necessary, intermittent short term therapy is highly recommended to prevent rebound lowering and hypoascorbicacidemia after cessation of therapy.