Lanthanide markers in a single sample for nutrient studies in humans.

Multiple Lanthanide markers were used to develop procedures for determinations of intake and apparent utilization of four nutrients using data from fecal analysis and known concentrations of markers in nutrients. Terbium oxide was given as the intake marker. All foods contained the other non-absorbed markers, each marker in direct proportion to the amount of a specific nutrient in each food. Nutrient markers were oxides of samarium, scandium, ytterbium, and europium. Fecal collection and subsequent analysis of nutrients and markers were completed. Fecal marker concentration stabilized 2 days following initiation of the marker regime. Thus, after 3 days, a single grab sample could be utilized to analyze for nutrient utilization. The ratio of nutrient marker proportional to nutrient and intake to nutrient excretion provides the data for the calculation of apparent utilization for as many nutrients as nutrient markers incorporated into the food. When direct and marker methods of determining nutrient intake and apparent utilization were compared, no significant differences were found for gross energy, fat, protein, and calcium.