Thymosin Alpha-1 and Longevity and Anti-Aging: What Has Been Studied

What the research covers

A PubMed search found no study of thymosin alpha-1 and human lifespan. A trial in older men measured the response to a flu shot instead.

A 1989 double-blind trial enrolled 90 men aged 65 to 99. They got the peptide or a placebo along with the 1986 flu vaccine. The dose was 900 micrograms per square metre of body surface. It was given as a shot under the skin twice a week, for eight doses. The trial counted how many men had a four-fold rise in flu antibodies. No toxic effects were seen in either group. The indexed abstract stops before the results.

In the TESTS trial, 1,106 adults aged 18 to 85 with sepsis got the peptide or a placebo. Deaths by day 28 did not differ overall. A planned check by age hinted that the effect might differ with age. In people 60 and over, the hazard ratio was 0.81. Its range, 0.61 to 1.09, includes no effect at all. In the peptide group, deaths by day 28 were higher under age 60 (hazard ratio 1.67, range 1.04 to 2.67). A post hoc analysis in the same paper, adjusted for organ support, suggested it might not have raised deaths in that group.

A 2026 Cochrane review of thymosin alpha-1 for chronic hepatitis B looked at 10 trials. Among the trials that reported age, participants were 17 to 75. The review rated that evidence as very low certainty for all but one outcome. In a 1988 rodent (mouse) study, blood levels of the peptide fell sharply from 3 weeks to 2 months of age. Any later fall with age was mild.

Sources

1. Gravenstein S, Duthie EH, Miller BA, et al. Augmentation of influenza antibody response in elderly men by thymosin alpha one. A double-blind placebo-controlled clinical study J Am Geriatr Soc (1989). PMID 2642497 doi:10.1111/j.1532-5415.1989.tb01561.x Randomised double-blind trial, 90 men aged 65 to 99, with the 1986 flu vaccine; measured antibody response, not lifespan.
2. Wu J, Pei F, Zhou L, et al. The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial BMJ (2025). PMID 39814420 doi:10.1136/bmj-2024-082583 TESTS sepsis trial; no overall difference in 28-day deaths; planned age subgroup analysis reported.
3. Naing C, Ni H, Aung HH, et al. Thymosin-ɑ1 for people with chronic hepatitis B Cochrane Database Syst Rev (2026). PMID 42713852 doi:10.1002/14651858.CD014610.pub2 Cochrane review of hepatitis B trials; among trials reporting age, participants were 17 to 75; certainty very low for most outcomes.
4. Weindruch R, Naylor PH, Goldstein AL, et al. Influences of aging and dietary restriction on serum thymosin alpha 1 levels in mice J Gerontol (1988). PMID 3346517 doi:10.1093/geronj/43.2.b40 Rodent (mouse) study: blood thymosin alpha-1 fell mainly in early life; later declines were mild.