Carnitine · L-Carnitine Tartrate · LCLT
Shuttles fatty acids into mitochondria — critical for fat oxidation and recovery.
FDA
Approved
WADA
Not Listed
HALF-LIFE
~17 hours
ROUTE
Oral / IV
SCHEDULE
Daily, pre-workout or with meals
In Plain English
Shuttles fatty acids into mitochondria — critical for fat oxidation and recovery.
Status & Legality
NATTY?
No Test ExistsNo established test exists for this compound.
FDA
ApprovedFDA approved for human use.
WADA
Not ListedNot currently on WADA prohibited list.
COMPOUNDING
Rx AvailableAvailable at licensed pharmacies with prescription.
PRESCRIBED
By prescriptionPhysicians can prescribe this compound legally.
ROUTE
Oral / IVAdministration via oral / iv.
Fatty acid transport
Fat oxidation
Exercise recovery
Cardiovascular support
L-Carnitine is an amino acid derivative that transports long-chain fatty acids across the mitochondrial membrane for beta-oxidation. Without adequate carnitine, fats cannot enter the mitochondria and accumulate instead. It is conditionally essential — synthesized endogenously but often insufficient during high-output exercise, caloric restriction, or aging. Carnitine Tartrate (LCLT) is preferred for athletic use; Acetyl-L-Carnitine (ALCAR) crosses the blood-brain barrier for cognitive benefits.
Fishy body odor at high doses (gut bacteria metabolize it to TMAO)
Nausea
GI cramping at high doses
Mild headache
Taking without carbohydrates — insulin is required for carnitine muscle uptake; absorption into muscle tissue drops significantly without a carbohydrate-containing meal
Confusing L-Carnitine Tartrate and ALCAR — LCLT is for athletic and fat oxidation performance; ALCAR crosses the blood-brain barrier for cognitive and neurological benefits
Expecting immediate fat loss — tissue carnitine levels require 4+ weeks of daily supplementation to build to functional levels
Thyroid hormones — L-Carnitine inhibits cellular uptake of thyroid hormones; potential concern for hypothyroid patients
Blood thinners — mild antiplatelet effect at high doses; monitor
D-Carnitine — if supplements contain D-Carnitine (contamination or poor quality), it competitively inhibits L-Carnitine uptake; verify supplement quality
L-Carnitine works but requires patience and consistency — tissue levels take 4+ weeks to build. The insulin-dependent uptake mechanism means taking it with a carbohydrate-containing meal is not optional; it's how carnitine gets transported into muscle. If cognition is the primary goal, switch to ALCAR — the acetylated form that crosses the blood-brain barrier.
Stats
Sources & Studies
Koozehchian MS. et al., J Exerc Nutrition Biochem, 2018