In the thread you linked, where you claimed that fasting would clean up damaged mitochondria that were not signalling mitophagy (evidence?) I posted a paper that looked at glycation in intervertebral discs in a population from 16 to 95. In the paper that you criticize for having a median age in the 40's, bear in mind the definition of median-- Half the people were younger than that.
First, it is not my claim that starvation greatly upregulates mactoautophagy of all kinds, including mitophagy. This is the state of the current knowledge, which I learned from reading countless papers on the topic (you get the latest scoop from the intro section and following the relevant refs). I stand by my knowledge and can only repeat here, for the convenience sake:
Here is, briefly, what's missing in de Grey scenario: When a cell is starving, all forms of macroautophagy are greatly upregulated. Soon after the scarcity of nutrients is sensed, mitochondria begin to fuse into large thread-like aggregates. Apparently, mitochondria were first observed in a starving cell, hence the origin of the name: mitochondria means thread-like -- this usually comes as a surprise to people who are accustomed seeing illustrations of unitary mitochondria depicted as barrel-shaped objects.
Now there are two relevant reasons why mitochondria fuse into large, thread-like aggregates when nutrients become scarce. First, this helps them to generate more energy for the cell, thus increasing ATP output for a given input. The second reason is crucial here: this prevents them from being gobbled up when indiscriminate autophagy is unleashed in a starving cell. And when indiscriminate autophagy is raging in a cell, just about any protein 'lying around unattended' or any organelle small enough to fit into autophagasome 'mouth' gets recycled. Please note: in the conditions of starvation, no additional tags or special signaling are required. Now note this: because damaged mitochondria are generally unable to fuse with the healthy ones, they remain in their unitary form and thus become easy pickings for autophagasomes.
Now, as far as I remember, the bulk of papers that deal with damaged mitochondria having difficulty fusing with healthy ones came out around 2005, which is after the de Grey paper on mitochondria but well before the post by Reason on this topic in FightAging (and before Ending Aging came out). That's one of the problems with SENS and their followers. They don't seem to be engaged in 'continuous education' and instead always refer to the ~8 year old Ending Aging as if it was something set in stone.
Regarding the studies you linked, I have already pointed out the problem with their cohorts. The nub of our disagreement lies in my claim that
damage does not accumulate while we're young, which, it is generally agreed, for most people, is under 25. Therefore, to make your point, a convincing study should demonstrate that damage accumulates in the cohort <25. The ideal range would be 18-24. Would they find the correlation to be statistically significant?
Finally, your lofty sounding definition of damage as "a process that occurs on the molecular level" is impractical considering that the halflife of an average protein in a body spans from minutes to hours, though some last years. And, as I have already pointed out in the other thread, in a multicellular organism, at any given point in time cells get damaged, die and are replaced, which is especially true of epithelia. So, when you talk about the molecular damage, what is your precise definition of it? How would you capture it in practice, if the very process of life involves continuous creation and destruction?
Edited by xEva, 03 December 2014 - 02:18 AM.