Vitamin A is often called the anti-infective vitamin, and this anti-infective value is believed to be especially operative in the prevention of bacterial invasion of mucous membranes.1 Because of this alleged protective value, substances containing this vitamin are being advocated extensively, without adequate experimental proof, for prophylaxis against the common cold. The common cold and its complications are of such great importance that it seemed desirable to determine whether or not the addition of vitamin A to the diet has any effect on the prevention, duration and severity of the disease. In the present communication we are reporting the results of such a study. Recently, somewhat less detailed and shorter studies have been reported in infants by Wright2 and by Hess and his co-workers.3 Our own investigation has been limited to observations made on young adults.
From a practical standpoint, it seemed far more important to compare