Ingredient Repository · Ingredient

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Ingredient

L-Carnitine

An amino acid derivative that shuttles long-chain fatty acids into mitochondria for cellular energy production and fat oxidation.

What it is

L-Carnitine is a naturally occurring amino acid derivative synthesized endogenously from lysine and methionine, concentrated in skeletal and cardiac muscle. In cellular metabolism, l-carnitine acts as an essential cofactor for carnitine palmitoyltransferase-1 (CPT-1), shuttling long-chain fatty acids across the inner mitochondrial membrane into the mitochondrial matrix for beta-oxidation and ATP energy generation. L-Carnitine L-Tartrate (LCLT) is the preferred rapid-release form used in athletic and endurance performance supplements.

Also known as: L-Carnitine L-Tartrate, Levocarnitine, Acetyl-L-Carnitine

What it does

  • Shuttles long-chain fatty acids into mitochondria for beta-oxidation and energy.
  • Reduces exercise-induced muscle damage, soreness, and metabolic fatigue.
  • Supports cellular recovery, androgen receptor density, and endurance stamina.

Amplified by probiotics

L-Carnitine is absorbed in the small intestine via organic cation transporter 2 (OCTN2/SLC22A5). Unabsorbed carnitine passing into a dysbiotic colon can be fermented by specific gut microbiota (such as Emergentia or Desulfovibrio species) into trimethylamine (TMA), which hepatic enzymes convert into trimethylamine N-oxide (TMAO), a vascular risk marker. Microencapsulated probiotics (Lactobacillus and Bifidobacterium) promote efficient small intestinal OCTN2-mediated absorption and foster a healthy gut microbiome that lacks TMA lyase pathways. This ensures maximal l-carnitine bioavailability for mitochondrial oxidation while suppressing unwanted TMA/TMAO generation.

Typical dose

1,000–3,000 mg/day (L-Carnitine L-Tartrate)

The evidence

Evidence: strong

Clinical trials and systematic reviews establish that L-carnitine supplementation significantly attenuates exercise-induced muscle damage, decreases serum lactate and creatine kinase, and speeds post-workout recovery (Fielding et al. 2018, Nutrients). Meta-analyses also confirm significant improvements in body weight and fat mass parameters in overweight adults (Talarez et al. 2020, Clin Nutr ESPEN).

  1. Fielding R, et al. L-Carnitine Supplementation in Recovery after Exercise. Nutrients. 2018;10(3):349. PubMed ↗
  2. Talarez M, et al. The effect of L-carnitine supplementation on lipid profile in adults: a systematic review and meta-analysis of randomized controlled trials. Clin Nutr ESPEN. 2020;36:1-11. PubMed ↗

Safety & who should check first

Excellently tolerated at 1–3 g/day. High doses (>5 g/day) may cause mild nausea, abdominal cramps, or fishy body odor. Safe for long-term athletic and metabolic support.