THE APPRAISAL OF NUTRITIONAL STATUS (NUTRITURE) IN HUMANS: With Especial Reference to Vitamin Deficiency Diseases

Abstract

A classification and definition of zones of nutriture (or degrees of nutritional status) is made as follows: (1) saturation (with sub-zone of excess); (2) unsaturated, but functionally unimpaired; (3) potential deficiency disease; (4) latent deficiency disease; (5) clinically manifest deficiency disease. It is suggested that the 2d zone represents adequate nutriture; there is no cogent evidence that any higher level is more beneficial to health in the human; in this case," optimal" nutriture can not be differentiated from adequate nutriture. The data for assessing nutriture are obtained in 3 ways: by clinical examination, by biochemical and physiological tests, and by measurement and estimation of food intake. Clinical examination detects only the well developed deficiency disease and must be supplemented by other evidence. Recent claims that the diagnosis of some of the avitaminotic diseases may be made solely on biomicroscopic examination of certain tissues have been weighed and found wanting. The interpretation of most of the biochemical tests is uncertain; they have not been correlated with the production and cure of the clinical signs of the disease in human subjects. The dietary standards widely employed in estimating dietary adequacy were not designed as standards of adequacy and are not founded on sufficient data on human subjects; they give false excessive measures of the incidence of deficiency conditions. The estimates of widespread deficiency disease in this country (Bull. 109, Nat. Res. Council) depend largely on estimation of the dietary intake and upon biochemical tests, and are therefore unreliable. Future advances in the means of appraising individual nutriture will rest upon elaboration of knowledge of the biochemistry, physiology, and pathology of the vits. in man. This can be attained (1) by investigations in which clinical deficiency diseases are produced and cured in a considerable number of subjects; (2) by careful studies of those spontaneously occurring cases of dietary or conditioned deficiency disease. Such studies will lead to more accurate evaluation of the nutriture of populations, and facilitate the search for correlations between nutriture and the quality of health of a population.