THE reliable methods for the determination of vitamin A in the blood plasma or serum has greatly contributed to the knowledge of the function of vitamin A in the human organism. During the past five years my associates and I have published certain studies on plasma vitamin A.1 I wish to present here some of these results, together with other reports from the literature which, I believe, are of interest to the pediatrician.
VITAMIN A IN THE HUMAN BODY
The more our studies progressed the more it became evident that the plasma vitamin A is largely independent of the dietary intake of vitamin A or its precursor carotene. In several nutritional surveys, it was reported that the values for plasma vitamin A for well nourished persons are on a higher level than those for poorly nourished ones.2 We observed that the plasma vitamin A values of persons from