All:
With the retraction of that study I'd linked above, does anyone still feel there's enough evidence for the value of this compound as an anti-aging supplement?
If so, what do you feel is convincing about it (specific references appreciated)?
Something that interferes with mitichondrial function and causes the production of free radicals doesn't seem particularly like a good thing to supplement all the time. Maybe once in a while?
The mTOR-related retraction should have no impact whatsoever on one's decision on whether to take Ca-AKG. All it means is that the reported effect on mTOR is not supported by this paper — which
as I noted earlier actually resolves a tension in the literature, since Kennedy and Lithgow affirmatively report that it has
no effect on mTOR in several tissues in mice. And the retracted paper originally claimed that AKG
boosted mTOR activity, which if anything would have made people
cautious about taking it, since mTOR
inhibition is one of the most robustly supported means of retarding aging across the animal kingdom.
So now we appear to know that Ca-AKG's anti-frailty, bone anabolic, and (very slight) life-extension effects (in mice!) are not due to increasing mTOR activity. If anything, that's a
bonus.
You shouldn't base your decision on whether to take supplement, or do anything, simply because of an effect on some putative
mechanism, unless an effect on some mechanism is affirmatively reported that might be toxic and would not have surfaced in
in vivo studies at the moment of evaluation. You should make decision based on
actual health and longevity benefits reported
in vivo. "Activates SIRT1," "inhibits mTOR," "raises RBC NAD," etc are not
benefits: they're
potential explanations for benefits when such benefits are observed
in vivo.
Now, an effect on ROS is obviously not neutral in the way that a non-effect on mTOR is. However, while the review correctly notes this effect has been reported in
C. elegans, one should generally ignore anything that isn't reported in things with backbones. Indeed, the review goes on to say,
[Such a] moderate increase in ROS production could have beneficial effects due to induction of low intensity (mild) oxidative stress that triggers adaptive response to sufficient protection against any other stresses and thereby contributes to lessening functional decline of various processes with age (Lushchak, 2011, 2014a; Sies, 2015; Ristow and Schmeisser, 2014; Palmeira et al., 2019). In line with this, AKG supplement prevented an age-related increase in oxidative damage to biomolecules and modulated antioxidant defense in the aged mice (Niemiec et al., 2011) and aged yeasts (Burdyliuk and Bayliak, 2017). Finally, one should not ignore the fact, that AKG possesses antioxidant activity itself (Sokołowska et al., 2009; Fedotcheva et al., 2006; Bayliak et al., 2016b) and, hence, some beneficial effects of AKG can be caused by its direct antioxidant action.
Absent an affirmative finding of a
sustained increase in mtROS
in mammals (ideally, resulting in accelerated accumulation of mtDNA mutations), I would ignore the putative effect reported in worms in light of the reported benefits and the somewhat contrary findings of Niemiec et al.
Edited by Michael, 09 September 2021 - 09:09 PM.