A Critical Review: Vitamin B Deficiency and Nervous Disease.

AFFECTIONS of the nervous system which result from inadequate nutrition have assumed an increasingly important position through the rapid accumulation of clinical, experimental, and pathological data. The artificial synthesis of a number of the components of the vitamin B complex has made available pure crystalline material in large amounts for clinical research, and thus a milestone in the history of these affections has been passed. It now seems appropriate to review and summarize the knowledge of these important substances. To evaluate the status of a nutritional deficiency in man is difficult. As a rule the patient induces his own disease and provides a deficiency that is not quantitatively measurable, but frequently clinical and laboratory evaluations are attempted. Both the laboratory method and the clinical method have certain advantages. Mice are not yet men and until they are the work coming -from the study of human beings is essential. Since the experience of investigators working with animals may often point the way for clinical research, we have interspersed in this review a few of the pertinent studies on the effect of nutritional deficiency on the nervous system of animals. A scheme for illustrating the multiple factors of the vitamin B complex is given in Fig. 1. To date the following portions of the vitamin B complex have been isolated and synthesized in amounts sufficient to allow for clinical trial: thiamin hydrochloride, nicotinic acid, riboflavin, and 2-methyl, 3-hydroxy, 4, 5-di (hydroxymethyl) pyridine. The deficiencies of these substances as they apply to the nervous system of man will be discussed briefly.