If a peptide worked in rats, why isn't that enough to say it works in people?
Updated: 2026-09-09 · Safety and evidence
Short answer
Animal studies exist to generate hypotheses and flag toxicity signals, not to claim something works in people. Species differences, the amounts used, artificial disease models and effect sizes mean a majority of promising preclinical results are not reproduced in human trials.
In plain English
- An animal model is a simplification of a disease, not the disease.
- Amounts used in preclinical work do not translate directly to people.
- Animal studies are usually small and run under tightly controlled conditions.
- 'Promising in mice' is a legitimate starting point, not a conclusion.
What we know
- Preclinical research is a required and useful step before human studies.
- Much of the BPC-157 and TB-500 literature is preclinical.
What we don't know yet
- There is no reliable way to predict which animal finding will hold in humans.
- Effects seen in animals do not let you estimate human safety.