L-Carnitine
Amino-acid derivative that shuttles long-chain fatty acids into mitochondria for ATP production. The classic 'fat-loss' supplement that has actual mechanism, when dosed correctly.
What it actually is
Not a peptide. L-Carnitine is a quaternary ammonium compound synthesized from lysine and methionine. It's not technically an amino acid, but it's amino-acid-derived. Required for any cell that burns fatty acids for energy, it's the gatekeeper that lets fat into the mitochondria.
Why peptide users come across it
Pairs naturally with GLP-class peptides during cuts to help preserve fatty-acid oxidation when caloric intake drops. Common adjunct in body recomp protocols. Often stacked with ALCAR for the cognitive layer.
Mechanism
Transports long-chain fatty acids across the mitochondrial inner membrane via the carnitine shuttle (CPT-1, CACT, CPT-2 enzymes). Without enough carnitine, fatty acids can't enter the mitochondria for beta-oxidation. Higher carnitine pool = more substrate availability for fat-burning during exercise.
Documented dose range
Side effects
- TMAO elevation (gut bacteria convert excess carnitine; hypothesized cardiovascular concern, debated)
- Fishy body odor at high doses (3g+)
- Mild GI upset on empty stomach
- Insomnia if taken late in the day
Contraindications
- Hypothyroidism (can blunt thyroid hormone action)
- Active seizure disorder (rare interaction reports)
- Pregnancy (insufficient data on supraphysiological doses)
The Pepdex take
The L-tartrate form (LCLT) at 2g/day with a carb-containing meal is the working protocol. Without the insulin spike, oral absorption is poor (15-20% bioavailability). IV is the maximum-uptake route but expensive. Skip the cheap acetyl-l-carnitine if your goal is fatty-acid oxidation, ALCAR is more for cognition.
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