Please note that this is not fundamentally a Biology question. It relates to the properties of molecules containing Carbon and Nitrogen.
Carbon atoms are everywhere in living systems from sugars to proteins etc.
Carbon-14 is present in living systems in a certain percentage compared to Carbon-12.
This Carbon-14 is decaying to Nitrogen-14 even when the system is alive.
Does this effect the health and functioning of the living system at all ?
I mean take a glucose molecule $\ce{C6H12O6}$, suddenly one of the Carbon atoms randomly decays to a Nitrogen atom. Does this molecule continue to function as a glucose molecule ? This question extends to every molecule in the body that contains Carbon atoms.