In accordance to modern science, one would never expect significant deviation from natural distribution of isotopes for a given chemical element. It does not matter which object of nature this element belongs to, and where it is in our universe. These deviations are usually very small and measured in parts per million.
We have discovered that in fact changes of isotope concentrations in favor of heavier isotopes is a feature of abnormalities in various life forms from plants to mammals. Prevalence of heavy or light isotopes in live organisms can be considered as signatures for old and sick, and young and healthy correspondently.