Glycine propionyl-l-carnitine

Amino-acidCarnitine derivative

What is it

Glycine propionyl-L-carnitine (GlycoCarn or GPLC) is a salt combining propionyl-L-carnitine (an ester form of carnitine) with glycine. It is marketed for cardiovascular and exercise performance.

Evidence for 2 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Peripheral arterial disease / claudication

Good Evidence

Several trials of propionyl-L-carnitine (often as GPLC) show improvements in walking distance and symptoms in PAD.

Exercise performance / blood flow

Limited Evidence

Some studies show improvements in nitric oxide markers and performance; others show no effect. Evidence is mixed.

How it works

Propionyl-L-carnitine supplies a propionyl group that enters the citric acid cycle, supporting energy metabolism in tissues with high oxidative demand (heart, skeletal muscle). It also supports nitric oxide production, potentially improving blood flow. Clinical research, mostly with the GlycoCarn brand, has examined effects on peripheral arterial disease, claudication symptoms, and exercise performance. Evidence is moderate for cardiovascular applications, more limited and mixed for athletic performance.

Dosage

Studies typically use 1-4.5 g of GPLC daily, often divided into 2 doses. Performance studies use 4.5 g (often as a single pre-workout dose).

When and how to take it

WHEN: Often pre-workout for athletic use; divided doses for cardiovascular use. HOW: With water; may be taken with or without food.

1 commercial form

Compare the main delivery options and what they’re best suited for.

GlycoCarn (GPLC)

Glycine-conjugated propionyl-L-carnitine.

Branded form used in most clinical studies.

Safety

Generally well tolerated. Side effects can include GI upset, nausea, and (rarely) fishy body odor (related to TMAO production from carnitines). Long-term carnitine intake has been associated with elevated TMAO, a marker linked to cardiovascular risk in epidemiological studies; clinical significance is debated.

Who should be cautious

Caution with seizure disorders (carnitine effects on seizures are mixed) and hypothyroidism. Limited safety data in pregnancy.

Interactions

May enhance effects of nitric oxide-related medications. Theoretical interaction with thyroid hormone replacement (large carnitine doses can blunt thyroid action in some studies).

Frequently asked questions

Is GPLC better than regular L-carnitine?⌄

Propionyl-L-carnitine has stronger evidence for cardiovascular applications than L-carnitine alone. Whether the glycine component adds benefits beyond propionyl-L-carnitine is debated.

References

Glycine propionyl-l-carnitine on Wikidata — Wikidata link

Glycine propionyl-l-carnitine on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Glycine propionyl-l-carnitine (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.