Two reviews on beneficial effects of mild stress, starting with a 2024 paper coauthored by the lead researcher of Sulforaphane in the Goldilocks zone:

“This paper addresses how long lifespan can be extended via multiple interventions, such as dietary supplements, pharmaceutical agents, caloric restriction, intermittent fasting, exercise, and other activities. This evaluation was framed within the context of hormesis, a biphasic dose response with specific quantitative features describing the limits of biological/phenotypic plasticity for integrative biological endpoints.

Human maximum longevity has remained relatively constant in the 110–120 year time period. Yet, research with C. elegans indicates that hormetic processes increase both average (median/mean) and maximum lifespans. These observations were consistently shown by different research teams using highly diverse stressors but with generally similar experimental methods. Thus, lifespan can be increased in an overall average manner but also within the context of the maximum lifespan potential via hormetic processes, which has not been shown to occur in human population studies.

In multiple experimental and epidemiological contexts, antioxidants have prevented lifespan extension of numerous hormetic agents and blocked human health benefits (e.g., exercise), supporting the hypothesis that oxidative stress is necessary for healthspan improvements and lifespan extension.

Maximum lifespan may be prolonged by extending the lifespan of healthy subjects. Median lifespan would be enhanced by protecting those who are susceptible to genetic/environmental diseases.

Most experimental studies indicate that maximum hormetic lifespan benefits are in the 15 – 25% range when responses are optimized. Human-based benefits could be expected to be less than this maximum range. The issue of hormetic synergies is important to consider, but the available data to date indicates that these benefits are also constrained by limits of biological plasticity.”

https://www.sciencedirect.com/science/article/abs/pii/S1568163723003409 “Hormesis determines lifespan” (not freely available) Thanks to Dr. Evgenios Agathokleous for providing a copy.

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A 2023 review of nematode studies was cited three times:

“While stress response pathways are important in allowing organisms to survive acute and chronic stresses, these pathways also contribute to longevity under unstressed conditions. Multiple stress response pathways are required for normal lifespan in wild-type worms, and all of the stress response pathways discussed in this review contribute to the longevity of long-lived mutants.

Four stress response pathways were consistently required for longevity:

1. The FOXO transcription factor DAF-16-mediated stress response;
2. The Nrf2 homolog SKN-1-mediated oxidative stress response;
3. The cytoplasmic unfolded protein response (cyto-UPR); and
4. The endoplasmic reticulum unfolded protein response (ER-UPR)

are required for normal lifespan, and may contribute to the extended lifespan of long-lived mutants. Developing strategies to activate these pathways, at the right time(s) and in the right tissue(s), may help to promote healthy aging and ameliorate age-onset disease.”

https://www.sciencedirect.com/science/article/pii/S1568163723001009 “Biological resilience and aging: Activation of stress response pathways contributes to lifespan extension”

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