Thymulin
Early humanZinc-dependent thymic nonapeptide hormone / T-cell differentiation factor · Also known as Facteur Thymique Serique, FTS, serum thymic factor, Zn-FTS, zinc-bound thymic nonapeptide
Overview
Thymulin (originally called Facteur Thymique Serique, FTS) is a nonapeptide hormone produced by thymic epithelial cells whose biological activity depends on being bound to zinc in a one-to-one ratio. In its zinc-bound form it induces T-cell differentiation and enhances functions of several T-cell subsets, and its plasma level — high early in life — declines to nearly undetectable by roughly the fifth decade, paralleling thymic involution. Most of the human data is descriptive: studies have measured reduced thymulin activity in malnutrition, zinc deficiency, anorexia nervosa and aging, and have explored the zinc-thymulin relationship. What is largely missing is controlled human efficacy trials showing that supplementing thymulin (or analogs) improves clinical outcomes, so the popularly marketed immune-restoration claims rest mainly on mechanism, animal work and observational human associations. It is not FDA-approved for any indication.
Commonly Reported Uses
These are uses commonly discussed or marketed by users and vendors — not a list of proven or approved benefits, and not a recommendation.
- Immune restoration / age-related immune decline (marketed claim; mechanism and observational data, no controlled human efficacy trials)
- Support during zinc deficiency or malnutrition-related immune impairment (observational human associations; not an approved therapy)
- General anti-aging / 'thymic rejuvenation' (marketed claim; not established)
What to Track
Data points you and your clinician might monitor. For observation only — not a diagnostic protocol.
- Labs — serum zinc (thymulin activity is zinc-dependent) if a clinician is monitoring
- Labs — white-cell count and lymphocyte subsets if a clinician is tracking immune status
- Labs — hs-CRP for a general inflammation signal
- Subjective — frequency/severity of infections and energy over time
- WHOOP — recovery and HRV trends as a well-being signal
Sources & References
Quick Reference
- Class
- Zinc-dependent thymic nonapeptide hormone / T-cell differentiation factor
- Evidence Level
- Early human
- Reported Uses
- 3 listed
- Tracking Metrics
- 5 suggested
- Citations
- 3 sources
Safety & legal notes
NOT FDA-approved for any human indication; commonly sold 'research use only.' Human data is largely observational (measuring thymulin levels in malnutrition, zinc deficiency, anorexia and aging) rather than controlled efficacy trials of thymulin therapy. Because activity is zinc-dependent, claims and effects are entangled with zinc status. Not a primary WADA doping target, but athletes should verify current rules before using any research peptide. Long-term human safety is not established. Consult a licensed clinician.
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