Carnitine
The fat ferry. L-Carnitine is essential for transporting long-chain fatty acids across the mitochondrial membrane where they can be burned for energy. Without it, fat burning stalls and energy production suffers.
What Carnitine Does
Fat Transport
Shuttles long-chain fatty acids (14+ carbons) across the inner mitochondrial membrane for beta-oxidation.
Acyl-CoA Buffering
Binds excess acyl groups, preventing toxic accumulation and freeing up CoA for other reactions.
Heart Energy
Heart relies heavily on fatty acids for fuel. Carnitine deficiency severely impacts cardiac function.
Brain Function
Acetyl-L-carnitine (ALCAR) crosses blood-brain barrier, supports acetylcholine and neuronal energy.
Sperm Motility
Sperm require carnitine for energy and motility. Concentrated in epididymis and seminal fluid.
Exercise Recovery
May reduce muscle damage markers and improve recovery, especially with carbohydrate co-ingestion.
Forms of Carnitine
L-Carnitine
- Standard form for fat transport
- Good for heart, muscle, fat metabolism
- Doesn't cross blood-brain barrier well
- Tartrate form absorbs better
Acetyl-L-Carnitine (ALCAR)
- Crosses blood-brain barrier
- Supports cognitive function
- Donates acetyl groups for acetylcholine
- Better for brain and nerve support
How Your Body Makes Carnitine
Carnitine is synthesized from lysine and methionine, requiring several nutrient cofactors:
Lysine
Essential amino acid backbone
Methionine
Provides 3 methyl groups
Vitamin C
Essential hydroxylation cofactor
Iron & B6
Required for synthesis enzymes
Deficiency in any of these nutrients can impair carnitine production. Vegetarians may be at higher risk due to lower dietary intake.
Who May Benefit
Vegetarians/Vegans
Dietary intake near zero. Plasma levels 10-20% lower than omnivores.
Older Adults
Synthesis and absorption decline with age. Heart and brain may benefit.
Heart Conditions
Angina, heart failure, and post-MI patients may benefit from supplementation.
Male Fertility
May improve sperm count, motility, and morphology in subfertile men.
The TMAO Concern
Some gut bacteria convert carnitine to TMA, which the liver converts to TMAO - linked to cardiovascular risk in some studies.
Context Matters
Regular meat-eaters have more TMAO-producing bacteria. Vegetarians produce minimal TMAO from carnitine.
Practical Approach
Short-term use, reasonable doses, and a healthy gut microbiome minimize any potential concern.