Newer, more stable isotope studies provide more accurate quantification of protein turnover and steady state than older nitrogen balance studies.

“there have been new studies that have been done. These have been like more stable isotope studies. The major isotope that's used is the L13 carbon labeling phenyl alanine in which case these studies take a small cohort of people give them a known amount of protein with that isotope tracer and then that um tracer is oxidized when it's you know metabolized and that's measured through breath the oxidation of phenyl alanine right?”