I read a book about the Japanese people who live to extremely old ages (it was about a village that has many very old people in Japan/the world in it) and basically they don't use any fancy medical shit to do it (I'm sure they get doctors checkups and take vitamins and medications as directed). They just keep active after retiring, they grow their own vegetables and keep busy, they stay in a community/support network with friends and socialize often and their meals aren't some Soylent type shit but instead highly varied with like 5-8 different each time with things like a small plate of tuna, a small plate of rice, a small plate of cabbage etc (and whatever other stuff they eat in Japan). The vegetables they eat are grown by themselves and people in their neighborhood.
A lot of people who retire and do nothing end up dying pretty soon afterward, so keeping a bit mentally, socially and physically active is really crucial.
So in many ways when you compare Bryan's approach it is interesting to see the science/measurement stuff and his habits (like the sleep routine he has is pretty amazing and something I'm working on improving in my own life) but anything he is putting into his body (medication, supplements, blood etc) feels like it is trying to shortcut shit a little bit.
(I will say I'm not yet fully read up on his entire routine or medical stuff but I don't get the impression he is sitting down to a highly varied diet like the Japanese do or growing his own vegetable patch, but to be fair he isn't in his 70s or 80s just yet)