How often is every atom in my body replaced?

I once heard that every cell in your body is essentially replaced every 3 months, except brain cells which last for life. This doesn’t make much sense to me and was wondering if anyone had further information.

Assumming atoms from DNA, RNA, fat, protein, and whatever else I’m made of are broken down into urea, CO2, and everything I expel, how often can I expect to be completely “replaced” with regards to atoms? Are there some still lingering around since birth? Would it be possible to test this with some labelled phosphate or carbon?

apparently using radioisotopes, it is calculated that 98% of your atoms are replaced every year, from

Assuming you practice good oral higiene, the atoms in your teeth will not be replaced.

I am not so sure of that. In practice, the enamel wears away, and is replaced by the dentine. So even the minerals in the teeth are replaced. The minerals in the bones are similarly cycled.

Take this with a grain of salt as I have no cite, but I have heard that you replace most of your body’s cells every 7 years. I will try and find some references.

The link seems broken, but very interesting if true.

You’ll never replace all the atoms.

Even if you replace all the cells, and even if that is true of cells in the skeleton and teeth (which I don’t see how it could be), some atoms remain - or come back.

There are so many atoms inside you that if you release a cup of them into the Earthly biosphere and immediately move to the far side of the globe, within months or years enough will mix into your new environment that you’ll reconsume them.

Isn’t the liver another organ that doesn’t replace and can’t heal itself? Or is that just alcohol-induced cirhossis (sp?)

believe this is the correct link:

Here’s the relevent stuff from that link. Unfortunately, the site it’s hosted at doesn’t seem to be any sort of medical authority; in fact it has a sort of punk-rock feel to it.

There is replacement at different levels of form.

Organ level: A liver will repair itself very well if it is damaged. Also skin is shed and replaced rapidly. However chronic abuse of the liver can cause a change to the form (scarring/cirrhosis) that persists. Of course skin scars too.

Cellular level: Some cells remain for a very long time - eg some nerve cells. Some cells are replaced quickly eg red blood cells. However the molecules within cells are replaced constantly. Even though the form of the nerve cell remains, it is constantly exchanging its molecules with those in the environment.

Molecular/atomic level: Atoms are continuously swapping from one molecule to another as the body and the environment process chemical reactions. They keep going around and around. Some atoms in bones and teeth hang around for a very long time because they are locked up in a stable matrix. eg Lead and cadmium from the environment can become incorporated into bone. Fluoride is incorporated into the surface of the tooth enamal - this stays for a while, but is constantly worn away and needs to be topped up to maintain teeth hardness.

The question is, what is the rate of replacement within different levels of form?

      • Maybe so, but I like the concept: that all material objects are really just “waves” of loose particles in an atomic cloud–so that essentially, your atoms are only yours as long as you remain in one physical spot… as you walk down the street, particles strike the front of you and become embedded in the wave, and the excess particles are lost off the back, as the size of the wave that is You cannot hold them all… that the substance of anything doesn’t move, only the arrangements of waves that make it up move around…