Life extension after heat shock exposure: assessing meta-analytic evidence for hormesis.
Level 5 - mechanism / opinion, no new human data
Meta-analysis of animal experiments (Level 5 for clinical CEBM)
PubMed 23570942 · doi:10.1016/j.arr.2013.03.005
What was done
Comparative meta-analysis of data from 27 studies across 12 animal species testing the effect of heat shock exposure on lifespan, including moderator analysis of temperature, exposure duration, repeat frequency, and inter-shock intervals.
What was found
Heat shock did not measurably increase longevity in the overall meta-analysis, accompanied by substantial heterogeneity among studies. Higher temperatures, longer shock durations, more frequent repeats, and shorter recovery times between shocks all reduced the likelihood of life extension. The abstract reports no quantitative effect sizes or variance statistics.
Why it matters
This review challenges the assumption that mild heat-induced hormesis is a universal longevity intervention in animals, showing that potential benefits are constrained to narrow experimental windows.
Limits
Findings are derived entirely from non-human animal models with no clinical human data. High heterogeneity among studies was observed, and numerical effect sizes and confidence intervals are omitted from the abstract.
Cited by
- contradicts Short bursts of heat shock in worms and flies extend their life expectancy by approximately 20%.