title: Use of non-absorbable markers in studies of human nutrient absorption.
abstract: Neutron activation analysis signifies a new era in the methodology of studies on nutrient utilization in humans. Yet the classical metabolic balance technique incorporating inert, non-absorbable markers will continue to be an invaluable tool for such studies. This review describes the use and abuse of a number of 'classical' inert markers, and describes the potential use of radioactive and naturally-occurring isotopes, and of heavy metals. The paucity of data critically appraising markers in infant balance trials is apparent. The comparative merits of conventional markers--carmine, polyethylene glycol 4000, chromium oxide--should be assessed. Indeed, it might be argued that the advancing knowledge on the use of naturally occurring isotopes in adults should make similar studies on infants a priority.
mesh_terms: D000042:Absorption; D004396:Coloring Agents; D006801:Humans; D007223:Infant; D007227:Infant Nutritional Physiological Phenomena; D007554:Isotopes; D008670:Metals; D008863:Microspheres; D009747:Nutritional Physiological Phenomena; D009753:Nutritive Value; D011092:Polyethylene Glycols; D011868:Radioisotopes
chemical_list: D004396:Coloring Agents; D007554:Isotopes; D008670:Metals; D011868:Radioisotopes; D011092:Polyethylene Glycols