The very thing that keeps us alive is also what causes us to age and eventually die. When oxygen reacts with our food to release energy, it also releases free radicals called oxidants. These oxidants are toxic as well. When you leave any fruit out and it goes bad, it’s because it has been oxidized which causes it to rot. The same thing happens to our body when we breathe in oxygen. The oxygen helps convert the food into energy. But it also causes the release of oxidants into our body which start reacting inside us. We rust from inside out and hence age and die.
The body tries to store everything that you need from the outside world to survive. It stores enough food so that even if you don’t eat for few days you won’t die. It stocks up on water so that a few days need something; it keeps some of it as back up for possible shortages.
On other hand body doesn’t store enough oxygen, the most crucial component of staying alive, to last for more than just a few minutes. It doesn’t make sense at all. The only explanation can be that the body releases that despite being elixir, it also a poison which it can’t store.