The carotinoids and vitamin A of the blood

Abstract

The observations recorded in this paper clearly indicate the effect of the intake of carotene and xanthophyll upon the carotinoid content of the plasma. Relatively large amounts of those substances may pass through the placenta to the fetus. Vitamin A probably also passes through the placenta, but the fetus may also be able to form vitamin A from carotene. Normal infants and older persons readily absorb carotene from the diet or from solutions of carotene in oil, but the rate of absorption is slower than the rate of absorption of vitamin A. The low carotinoid content of the diet in early infancy and in the winter months explains the lower concentration of carotene and xanthophyll in the first six months of life and in the winter months. The mean vitamin A concentration of the plasma in normal persons reaches a constant level soon after birth and is not affected by season. The variations between single determinations are great. Infection causes a prompt and considerable fall in the concentration of carotene, xanthophyll and vitamin A in the plasma. This fall is due, in part, to low intake during infection, but is also due, in part, to fever. A few days after the temperature becomes normal, the vitamin A content of the plasma may rise considerably above normal. Xanthosis cutis in normal persons, in diabetics, and in hypothyroidism is associated with an increase of carotene in the plasma, less often of xanthophyll. In severe untreated diabetes the tissues may not be able to metabolize carotene rapidly. In nephrosis and in severe chronic nephritis hypercarotinemia may occur without xanthosis cutis. In Bright's disease the level of plasma vitamin A may be greatly elevated, probably because the liver fails to store it. In hypothyroidism the carotinoids of the plasma may be elevated and the vitamin A may be low. Successful treatment with thyroid substance corrects the anomaly. In celiac disease the carotinoids and vitamin A are not readily absorbed. The observations recorded in this paper clearly indicate the effect of the intake of carotene and xanthophyll upon the carotinoid content of the plasma. Relatively large amounts of those substances may pass through the placenta to the fetus. Vitamin A probably also passes through the placenta, but the fetus may also be able to form vitamin A from carotene. Normal infants and older persons readily absorb carotene from the diet or from solutions of carotene in oil, but the rate of absorption is slower than the rate of absorption of vitamin A. The low carotinoid content of the diet in early infancy and in the winter months explains the lower concentration of carotene and xanthophyll in the first six months of life and in the winter months. The mean vitamin A concentration of the plasma in normal persons reaches a constant level soon after birth and is not affected by season. The variations between single determinations are great. Infection causes a prompt and considerable fall in the concentration of carotene, xanthophyll and vitamin A in the plasma. This fall is due, in part, to low intake during infection, but is also due, in part, to fever. A few days after the temperature becomes normal, the vitamin A content of the plasma may rise considerably above normal. Xanthosis cutis in normal persons, in diabetics, and in hypothyroidism is associated with an increase of carotene in the plasma, less often of xanthophyll. In severe untreated diabetes the tissues may not be able to metabolize carotene rapidly. In nephrosis and in severe chronic nephritis hypercarotinemia may occur without xanthosis cutis. In Bright's disease the level of plasma vitamin A may be greatly elevated, probably because the liver fails to store it. In hypothyroidism the carotinoids of the plasma may be elevated and the vitamin A may be low. Successful treatment with thyroid substance corrects the anomaly. In celiac disease the carotinoids and vitamin A are not readily absorbed.