Stable isotopes for measurement of nutrient dynamics during pregnancy and lactation

Only a few of the advantages of stable isotopes have been illustrated here. However, two valuable concepts have emerged in recent years; (1) the use of multiple isotopomers for comprehensive studies of a nutrient system, and (2) the use of multiple tracers for parallel investigations of different metabolic systems. These concepts provide flexibility in the conduct of clinical research, however, precautions are necessary to employ them properly. Nearly every example described here can be traced back to a pioneering study by Schoenheimer and Rittenberg. Certainly we do them faster, and more precisely, and with a deeper understanding of the biology, but the credit for this wonderful tool belongs to the original visionaries.