[Ancesthntr]

“The obvious stupidity here is that if the blood of 16 to 25 year olds can keep you young, then 16 to 25 year olds would never get older.”

---

No, not really. From what I’ve read elsewhere on the subject of transfusing plasma from young animals and people to older ones, the younger plasma boosts the immune system of the older patients. In the normal course of events, everyone ages, and part of that is that your immune system becomes less effective over time. Boosting that system via young blood so that it is closer to optimum will extend life - but only if it prevents you from getting the flu or pneumonia or something else that might have killed you otherwise.

With regard to young people living forever because they have young blood...not even logically possible, because that is likely the age range at which your immune system IS at its optimum. You can’t improve upon optimum, even if your 16-year-old friend gives you some of his or her plasma. Oh, and optimum isn’t perfect - young people get sick, too, even with great nutrition and enough sleep.

[reformedliberal]

...the age range at which your immune system IS at its optimum. You can’t improve upon optimum, even if your 16-year-old friend gives you some of his or her plasma. Oh, and optimum isn’t perfect - young people get sick, too, even with great nutrition and enough sleep.
_________
Bear in mind that it is precisely these youths with their vital immune systems who die of over-active immune responses in the presence of flu+anti-viral treatment. IIRC, it is called a cascade effect.

I am not aware of any zero-sum conditions in the youth vs age situation. Upsides, perhaps. Downsides, too.

Also, how often does the infusion need to occur? Blood components have their own life span.

I gave plasma, once. It took a long time and I was exhausted for several days afterward. I wasn’t a teen, closer to 30 or so. Much more debilitating than just giving blood, as I recall.