A 2023 rodent study investigated two NRF2-activating compounds for their effects in increasing median and maximum lifespan:
“In genetically heterogeneous (UM-HET3) mice, the Nrf2 activator astaxanthin (Asta) extended the median male lifespan by 12%. Astaxanthin (Asta) is a naturally occurring xanthophyll carotenoid that is an efficient Nrf2 activator, with potent antioxidant activity, broad health applications, and excellent safety.
Asta is distributed systemically and incorporated into cellular membranes, where it spans and stabilizes the lipid bilayer and reduces lipid peroxidation. Asta localizes in mitochondria and protects against mitochondrial dysfunction. It has anti-inflammatory properties, showing equivalent efficacy to prednisolone in an animal model. Geroprotective mechanisms of Asta regulate FOXO3, Nrf2, Sirt1, and Klotho, and the influence of Asta on autophagy via modulation of AMPK (a direct upstream regulator of mTOR), PI3K/Akt, and MAPK (JNK and p38) signaling pathways.
The present Interventions Testing Program (ITP) study is the first evaluation of Asta in a mammalian lifespan model, so the target dose of 4000 ppm in the diet is based on chronic mammalian studies other than lifespan. Despite the fact that the average diet contained 1840 ppm Asta (only 46% of the target), median lifespans of male UM-HET3 mice were significantly improved.
Asta and dimethyl fumarate (DMF) are both Nrf2 inducers; while both had low concentrations sometimes in the diet, we used about 30 times more Asta, which may explain why it increased the lifespan in males while DMF had no effect. Amounts of DMF in the diet averaged 35% of the target dose, which may explain the absence of lifespan effects.”
https://link.springer.com/article/10.1007/s11357-023-01011-0 “Astaxanthin and meclizine extend lifespan in UM‑HET3 male mice; fisetin, SG1002 (hydrogen sulfide donor), dimethyl fumarate, mycophenolic acid, and 4‑phenylbutyrate do not significantly affect lifespan in either sex at the doses and schedules used”
This study repeated an astaxanthin supplier’s claims without investigating its low bioavailability issues mentioned in Astaxanthin bioavailability. No explanations were forthcoming for unintentional low doses of astaxanthin and DMF in the treatment chows.
A human equivalent for the intended astaxanthin dose was 22 mg (4000 ppb x .081 x 70 kg), whereas the actual dose human equivalent was 10 mg (1840 ppb x .081 x 70 kg). Dose/response studies weren’t performed, so no conclusions could be drawn as to whether the target dose or other astaxanthin doses may be optimal for increasing lifespan.
A previous ITP study of another commercial NRF2 activator (PB125) found no lifespan benefits. Maybe one day, ITP or others will come around to testing sulforaphane that has 80% bioavailability (regardless of sex) and dose/response studies, which should end the uncertainty about NRF2’s anti-aging effects.
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