CLINICAL FEATURES OF VITAMIN A DEFICIENCY

Abstract

The peculiar curative virtues of certain foods have been recorded at isolated periods since ancient times. Some of these observations are strikingly accurate and prophetic. Today, from the standpoint both of human experience and of laboratory research, it has been definitely proved that a natural food supply furnishes, and normal nutrition requires, other substances in addition to proteins, fats, carbohydrates, water and salts. Present knowledge concerning these accessory food factors, or vitamins, is rather the product of development than of any isolated discovery, and much of this development antedates the introduction of the word "vitamin." It is almost exclusively within the last quarter of a century that experimental investigation, to which American scientists have made numerous and valuable contributions, has, in addition to making fundamental discoveries, explained the rationale of such historic dietotherapeutic procedures, as, for example, the use of fresh vegetables and citrus fruits in the treatment of scurvy