What is that called when the elderly go into a state that makes it impossible for them to die?

Question:

I watched a show about it like 3 years ago and it was about some protein/enzyme/etc. that your body starts to produce once you reach a certain age; it like protects your organs and keeps you from dieing (unless from an outside source, like a car accident, of course). What is this called? Thank you!

Answers:
Are you sure it was a show and not SciFi? So far, very few elderly people have eluded death in the long run...

What is that called when the elderly go into a state that makes it impossible for them to die?

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