[New aspects of the biochemistry of vitamin C]

Our investigations have brought new aspects of the biochemistry of ascorbic acid to light: Ascorbic acid exceeds the functions of a vitamin, since it not only has its known cofactor roles for several enzymes, but also affects the regulation of the levels of the circulating thyroid and adrenal cortical hormones. In guinea-pigs the ability to detoxicate certain drugs, e.g. barbiturates, decreases with a minimal but not yet perilous supply of ascorbic acid. This symptom is connected with high blood levels of cortisol, which are probably also involved in the injuries to connective tissue known in scurvy. Guinea-pigs, which like man are dependent on ascorbic acid as an essential foodstuff, are able to adapt to high doses of ascorbic acid. Under these conditions they catabolize it at an increased rate. However, for a certain period after a sudden drop in the high dosage of ascorbic acid there is a danger that a hypovitaminotic, suboptimal metabolic state will develop. Oral and parenteral applications of ascorbic acid yield different results, since the organism limits the absorption of the physiological oral uptake. When this limit is exceeded, the liver in particular is unprotected and becomes swamped. The harmlessness of high doses of ascorbic acid probably holds true only in the case of oral uptake.