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Peptides / TB-500

Panel: recommendedThymosin beta-4 fragmentNot FDA approved

TB-500

TB-500 is a synthetic peptide based on thymosin beta-4, a natural protein found in almost every cell of the body that helps cells move and helps tissue repair itself. Products sold as TB-500 are usually a short active fragment of that protein, but what is actually inside them varies from seller to seller.

Reviewed for
Wound healing
Committee vote
8 yes, 6 no, 1 abstain
Strongest evidence
Animals
Legal to compound in the US
Not yet

Effects studied or claimed

What it is promoted for, and where each effect has actually been seen

  • Faster wound and skin healingAnimals
  • Repair of tendons, ligaments and muscleAnimals and horses
  • Less inflammation and scarringAnimals
  • Repair of heart and eye tissueEarly research

How it is thought to work

Thymosin beta-4 binds actin, one of the building blocks of a cell's internal skeleton. That helps cells crawl into a wound, and it also supports the growth of new blood vessels.

What the evidence shows

In animals and the lab

Wound, heart-attack and eye-injury studies in animals show faster repair. It has been used in racehorses to speed recovery, where it is banned.

In people

No published human studies of TB-500 itself. The full natural protein, thymosin beta-4, has been tested in people as eye drops for dry eye and as a wound gel, with mixed results and no approval so far.

Safety and unknowns

Unknown in humans. At the meeting an FDA official asked how the substance could be listed when nobody can say for sure which molecule is in products sold as TB-500. As with other growth-promoting peptides, a theoretical cancer concern has been raised. It is banned in sport by the World Anti-Doping Agency.

FDA review

Reviewed for wound healing. FDA staff recommended against it. The committee voted 8 to 6, with 1 abstention, in favour.

Committee votes are advice to the FDA. A peptide can only be compounded legally once the FDA adds it to the 503A bulks list through formal rulemaking, which has no fixed deadline.

Sources

Analysis

A fragment of a well-studied repair protein

Peptide Evidence IndexBiology 5.5/10In people 1/10Index 2.1, rank 10 of 15See the full index

TB-500 is a short synthetic piece of thymosin beta-4, a protein found in almost every cell that helps cells move and build new blood vessels. Most of the science concerns the full protein, not the fragment sold online. The landmark study came in 2004, when researchers showed in Nature that thymosin beta-4 helped heart muscle cells survive and migrate after a heart attack in mice (Bock-Marquette and colleagues).

In people, the full protein has been tested as eye drops for dry eye and corneal wounds and as a gel for skin ulcers, with mixed results and no approval to date. TB-500 itself has no published human trials. Its best-known real-world story is a doping case: in 2016 the Court of Arbitration for Sport banned 34 past and present Essendon AFL players for taking thymosin beta-4 during the 2012 season. It has also been detected in racehorses.

Our view. the biology of thymosin beta-4 is credible and well published, which lends TB-500 a scientific aura. But the fragment is not the protein, injected doses are guesswork, and there is no human evidence that it speeds recovery from injury.

Studies and reports cited

  1. Bock-Marquette I et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature, 2004
  2. CNN: Essendon players banned by the Court of Arbitration for Sport over thymosin beta-4, January 2016

Summary of published research for general information. It is not medical advice and not a recommendation to use this substance.

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General information, not medical advice. Do not buy or inject unregulated peptides.