L-Carnitine (ALCAR / Acetyl-L-Carnitine) vs Pantothenic Acid (B5)

Mechanism

L-Carnitine's primary function is transporting long-chain fatty acids across the inner mitochondrial membrane via the carnitine shuttle (CPT-I/CPT-II system) for beta-oxidation. Acetyl-L-Carnitine (ALCAR) additionally donates its acetyl group to form acetyl-CoA (bypassing pyruvate dehydrogenase) and serves as a precursor for acetylcholine synthesis. ALCAR crosses the blood-brain barrier, providing neuroprotective effects through mitochondrial energetics, reduction of lipofuscin accumulation, enhancement of NGF receptor sensitivity, and modulation of synaptic plasticity. It also reduces oxidative stress via upregulation of heme oxygenase-1.

Standard Dosing

500-2000mg ALCAR daily or 1000-3000mg L-Carnitine L-Tartrate (for exercise performance)

Timing

Morning on empty stomach for cognitive effects. Pre-workout for fat oxidation/performance. ALCAR for brain; L-Carnitine L-Tartrate for muscle/exercise.

Cycle Duration

ongoing

Side Effects

• Fishy body odor (TMA production by gut bacteria)
• GI upset/nausea
• Restlessness/insomnia (ALCAR)
• Increased appetite
• TMAO elevation (cardiovascular concern with L-Carnitine, less with ALCAR)

Contraindications

• Hypothyroidism (may worsen)
• Seizure disorders (conflicting data)
• TMAO concerns (see notes)

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Mechanism

Pantothenic acid is converted to Coenzyme A (CoA), the universal acyl-group carrier essential for >100 metabolic reactions. CoA is required for: fatty acid synthesis and beta-oxidation, citric acid cycle (acetyl-CoA entry), steroid hormone synthesis (pregnenolone from cholesterol), acetylcholine synthesis, melatonin synthesis, and Phase II detoxification (acetylation reactions). Pantethine (the active form) supports healthy lipid metabolism by inhibiting hepatic HMG-CoA reductase and fatty acid synthase, while stimulating fatty acid oxidation.

Standard Dosing

500mg pantothenic acid or 300mg pantethine twice daily

Timing

With meals. Split doses for pantethine.

Cycle Duration

ongoing

Side Effects

• Diarrhea at high doses
• GI discomfort
• Contact dermatitis (topical dexpanthenol)

Contraindications

• Hemophilia (theoretical concern: pantethine may have mild antiplatelet effect at high doses)

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