Biochemical appraisal of nutritional status in man

I T is my assignment to discuss some of the biochemical approaches shown to be of value in the assessment of vitamin nutrition in man. I will limit my discussion to certain re-cent advances in our basic knowledge of vita-mm metabolism that may lead to the develop-ment of new methods of nutritional diagnosis and to the presentation of some new informa-tion obtained by application of the technics currently in use. I am also taking the liberty of discussing only those vitamins currently considered to be of vital interest to public health nutritionists. THIAMINE Thiamine pyrophosphate is obligatory for the opening step of the reactions that feed into the citric acid cycle and is necessary in an analogous way in the metabolism of a-keto glutanic acid which occurs somewhat later in the cycle. Since, in the former case, the entrance of pynuvic acid into the citric acid cycle depends upon an adequate supply of thiamine pyro-phosphate, an elevation of pyruvic acid in the blood is observed in thiamine deficiency. Be-cause of this relationship, blood pyruvate levels have been studied in every conceivable fashion in an attempt to develop a test for thi-amine deficiency. Unfortunately, since many factors influence blood pyruvate levels, such determinations are usually no more sensitive o