Last verified: 17 days ago
L-Proline
Also known as: proline, L-Pro, (S)-pyrrolidine-2-carboxylic acid
Evidence under review. — Not yet rated
Amino acid found naturally in the body. Limited clinical evidence for oral supplement use.
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What it does
L-Proline is a naturally occurring amino acid that the body uses to build collagen and connective tissue. In the provided research, it appears primarily as a cryoprotectant — a substance used to...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
No established dose
What the Science Says
L-Proline is a naturally occurring amino acid that the body uses to build collagen and connective tissue. In the provided research, it appears primarily as a cryoprotectant — a substance used to protect biological tissues during freezing — and as a stabilizer in injectable immunoglobulin therapies. One study found it effective at preserving ovarian tissue during cryopreservation, comparable to the standard chemical DMSO, with a better safety profile. No established oral supplement dose exists based on the provided studies.
What It Doesn't Do
No evidence from these studies that taking L-Proline as an oral supplement builds collagen in humans. No proof it repairs joints or skin. No clinical data supporting anti-aging claims. Not shown to boost athletic performance. The cryopreservation benefits are a lab/medical procedure — not something you get from a capsule.
Evidence-Based Benefits
Protects ovarian tissue during freezing as effectively as DMSO with fewer toxicity concerns.
Weak EvidenceEffective at: 1.5 M solution (medical/lab use only)
Supporting studies (click to view on PubMed):
Used as a stabilizer in subcutaneous immunoglobulin therapies approved for nerve disease treatment.
Weak EvidenceEffective at: No established oral dose
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Unknown — no oral bioavailability data in the provided studies. Its use as a cryoprotectant and injectable stabilizer does not inform oral absorption.
Red Flags to Watch For
- No clinical trials in the provided data test L-Proline as an oral supplement at any dose
- Most research involves L-Proline as a lab reagent, drug stabilizer, or chemical catalyst — not a dietary supplement
- Marketing claims about collagen synthesis or joint repair are not supported by the provided evidence
- Appears in 1,000+ registered supplement products despite very limited direct clinical evidence for oral use
Products Containing L-Proline
See how L-Proline is used in these analyzed products:
Frequently Asked Questions
What does L-Proline do?
Amino acid found naturally in the body. Limited clinical evidence for oral supplement use.
What is the effective dose of L-Proline?
No established dose
Is L-Proline safe?
No clinical trials in the provided data test L-Proline as an oral supplement at any dose
What doesn't L-Proline do?
No evidence from these studies that taking L-Proline as an oral supplement builds collagen in humans.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25