Discover and read the best of Twitter Threads about #agebetter
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One of the problems in biomedicine is that attractive models are sticky, meaning that ppl still refer to them even though the underlying premises have been discredited. In science lingo attractive models = "truthiness." Sound right but they are wrong. Here's an example. /1
Ppl are highly influenced by the idea that sirtuins are central regulators of longevity. Many problems with this concept. 1st, SIR2 is only required for 1 (not both) models of yeast longevity. 2nd, there is NO FITNESS ADVANTAGE to yeast mother cells with long lifespans. /2
This means that it is not plausible that SIR2 was conserved as a longevity gene. 3rd, the mechanism by which SIR2 extends lifespan in yeast is not conserved in other organisms. 4th, SIR2 overexpression in worms, flies & mice doesn't make animals live longer. /3
Today's mailbag had this FAQ: I know that NAD is required to make ATP but is ATP also required to make NAD? Yes, in fact the bioenergetic demands of restoring NAD from different precursors differ. Trp to NAD costs the most ATP followed by NA and NAM. NR costs the least... /1
because the cell doesn't have to run the PPP to make the ribose & the ribose is already linked to the nicotinamide moiety. The failing heart & other tissues under metabolic stress activate AMP kinase to turn the NRK genes ON when NAD and ATP are down precisely for this reason /2
Rodents fed NR who are put under these conditions of metabolic stress are highly protected. That's the basic logic of oral NR: boost your resiliency, repair better & resist the challenges that come your way. #agebetter
