L-Carnitine
TL;DR
Amino acid derivative that shuttles fatty acids into mitochondria for energy production. Different forms have different targets: L-carnitine for heart/muscle, acetyl-L-carnitine for brain.
Safety: Generally well-tolerated. GI discomfort, fishy body odor at high doses. Concern about TMAO production from gut bacteria — relevance debated.
Cost: approximately $12-20/month.
Best for: Heart disease, Cognitive decline
What the research says
Meta-analysis by DiNicolantonio showed reduced mortality and arrhythmias post-MI. Some evidence for heart failure and angina. TMAO concern is debated.
Acetyl-L-carnitine form crosses BBB. Some trials show benefit in mild cognitive impairment and depression. See acetyl-L-carnitine entry for more detail.
L-Carnitine on Amazon
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Safety & practical info
GI discomfort, fishy body odor at high doses. Concern about TMAO production from gut bacteria — relevance debated.
May potentiate warfarin. High doses may affect thyroid hormone action.
Affordable. Different forms at different prices.
Sources for this page include published meta-analyses, systematic reviews, and NIH dietary supplement fact sheets. All claims reflect the evidence as of early 2026.
This is not medical advice. Consult your healthcare provider before starting any supplement, especially if you take medications.