Bottom line
Both are research-interest compounds, not proven human longevity interventions. Their mechanisms and human data should be judged separately.
| Question | Ergothioneine | Spermidine |
|---|---|---|
| Primary biological context | Specialized uptake and cellular stress research | Polyamine biology and autophagy-related research |
| Human evidence | Early outcome trials and cohorts | Dietary observational studies and a developing intervention literature |
| Food sources | Mushrooms and selected foods | Wheat germ, legumes, soy and other foods |
| Typical supplement amounts | Single- to double-digit milligrams | Usually low-milligram quantities; products vary |
| Research maturity | Emerging | Emerging to moderate, depending on outcome |
| Main research interest | Cognition, cellular protection, aging | Autophagy, cardiovascular and cognitive aging |
How to interpret this comparison
- Food-intake associations can reflect overall dietary patterns.
- Mechanistic plausibility does not establish lifespan extension.
- A direct head-to-head human outcome trial has not been identified.