I read an article that said most atoms in your body are replaced throughout your life, with the exception of a few very stable cells like certain neurons in the brain. I also read another article that said all the atoms in your brains neurons are eventually replaced. Anyone know the truth?
I read that the body replaces all its atoms, about every seven years. The body is constantly breaking things down, and replacing them, with the food we eat, being the main source of replacement atoms. In a sense we are what we eat in terms of atoms.
If a mother cell replicates, to form two daughter cells, she has to first pull in fresh materials from the blood supply, until there are enough material stored to make two daughter cells. Each cell cycle replaces half the atoms, with fresh atoms, that originated from our food and drink. Skin cells defoliate constantly, so each time new ones appear, half the atoms are replaced; exponential replacement. Hair gets cut and we need new atoms to make more hair.
But even cells like neuron, many of which never replicate, will still go through internal recycle, that takes down and rebuilds, adding new atoms as old atoms get flushed as waste.
Interestingly, the body's water molecules are replaced each millisecond, due to hydrogen bonding. The Oxygen will swap hydrogen atoms very frequently, so although H2O still appears, the H and O partners, for any given H2O molecule, are not the same for very long. This is connected to entropy. We drink water all the time and this enters the body and old water is expelled.