L-Carnitine
Shuttles fat into your cells' power plants. Your body already makes its own supply.
L-carnitine transports fatty acids into mitochondria, where they are burned for energy, and the body synthesises what it needs from the amino acids lysine and methionine, making true dietary deficiency rare outside specific metabolic disorders. Acetyl-L-carnitine (ALCAR) crosses into the brain more readily than other forms and is the version most often studied for cognitive ageing research, while L-carnitine tartrate is the form most used in sports and exercise-recovery trials. Propionyl-L-carnitine has its own research base focused on circulation, and all forms are generally well tolerated at typical supplement doses.
Forms and bioavailability
Not all forms are absorbed equally. The form on your supplement label affects how much your body can actually use.
| Form | Absorption | With food | Timing | Evidence |
|---|---|---|---|---|
| acetyl-L-carnitine (ALCAR) | Higher | Either | Morning | Likely |
| L-carnitine tartrate | Typical | Either | Either | Likely |
| propionyl-L-carnitine (PLC) | Typical | Either | Either | Likely |
| L-carnitine fumarate | Typical | Either | Either | Possible |
Stack Almanac tracks which carnitine form you're taking, since ALCAR, tartrate, and propionyl versions are studied for genuinely different uses despite sharing a name.
Track your L-Carnitine in Stack Almanac
Last reviewed: 2026-07-08. Reference values are adult-general RDAs. Individual needs may vary. This page is for informational purposes only and is not a substitute for professional medical advice.