Peptides are being sold online as miracle fixes for energy, healing, and longevity—but what if the science behind them is shaky, or even dangerous?

In this episode, Therese Markow and Dr. Leigh Baxt pull back the curtain on the peptide craze, revealing what we really know (and don't know) about these heavily marketed "biohacks." They discuss the complexities and risks of unapproved peptides, which are often marketed for health enhancement. Dr. Baxt explains what peptides are and speaks to those drugs that are FDA-approved, like GLP-1 agonists and insulin, but also highlights the safety concerns of unapproved peptides, such as BPC-157 and TB-500, which lack appropriate clinical trial data and are often synthesized in unregulated labs. Dr. Baxt emphasizes the importance of proper clinical trial processes and regulatory oversight to ensure drug safety and efficacy.

Key Takeaways:

• A peptide is just a short chain of amino acids. They can be created synthetically, they can be isolated, and they are natural. The body doesn't care whether a peptide is "natural" or synthetic; what matters is its exact molecular structure.

• FDA-approved peptide drugs go through years of rigorous testing in animals and humans to prove both safety and effectiveness before reaching the market.

• Calling something "scientifically proven" can be misleading when the underlying evidence is weak, preliminary, or based only on rat studies. Especially as much of the "science" cited on peptide marketing sites comes from small, limited animal, or cell studies, not large, controlled human trials.

• Just because a product is available online or from a compounding pharmacy does not mean it is FDA-approved, well-studied, or safe; consumers must look beyond hype and ask what evidence truly exists.

• A naturally occurring peptide is generally not going to be suitable for use therapeutically.

"You can say that something is scientifically demonstrated because it showed something interesting in a rat. The key is that the people may not ask that, because a lot of times people hear 'scientific terminology' and it makes something sound really legitimate, but it doesn't mean that there's solid data." — Dr. Leigh Baxt

Evaluation of Research Grade Peptides Marketed Directly to Consumers Reveals Extensive Variability in Purity and Measured Abundance: https://www.preprints.org/manuscript/202604.1748

Connect with Dr. Leigh Baxt:

Professional Bio: https://www.mskcc.org/profile/leigh-baxt

LinkedIn: https://www.linkedin.com/in/leigh-baxt-314b877

Connect with Therese:

Website: www.criticallyspeaking.net

Bluesky: @CriticallySpeaking.bsky.social

Instagram: @criticallyspeakingpodcast

Email: theresemarkow@criticallyspeaking.net

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