Glycine Propionyl-L-Carnitine (GPLC)
A molecular complex of propionyl-L-carnitine and the amino acid glycine, marketed as a pre-workout 'nitric oxide' and endurance supplement. A few small trials report modest increases in nitric oxide markers and peak power, but the human evidence base is thin.
01 Overview
Glycine propionyl-L-carnitine (GPLC) combines propionyl-L-carnitine with glycine, sold under the trade name GlycoCarn. The marketing rationale is enhanced nitric-oxide production and blood flow layered on top of the carnitine family's metabolic role, aimed at endurance and pump-focused athletes.
A handful of small placebo-controlled studies report modest rises in plasma nitrate/nitrite and small improvements in peak anaerobic power and reduced lactate, but sample sizes are small and results inconsistent. It is best regarded as a plausible but weakly evidenced ergogenic aid rather than an established one.
02 Mechanism
Supplies propionyl-L-carnitine for muscle fatty-acid metabolism and anaplerosis, combined with glycine; proposed to increase nitric-oxide availability and blood flow.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Pre-workout | 1–4.5 g/day | Oral | Doses of ~1-4.5 g used in the small trials. |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Increased nitric-oxide markersSmall trials report raised plasma nitrate/nitrite. | modest | Observational | |
| Improved peak anaerobic powerSome studies show small gains in peak power and reduced lactate; results inconsistent. | small | Observational |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Gastrointestinal upsetNausea reported at higher doses. | Mild | Uncommon | Observational | |
| Carnitine-family odour / TMAOPotential trimethylamine odour and raised TMAO with chronic high use. | Mild | Rare | Observational |