Evidence Level
Moderate
L-carnitine is a supplement where form matters enormously. As a fat burner, it is overhyped — healthy omnivores have saturated muscle carnitine stores, and oral supplementation barely raises muscle carnitine levels without concurrent carbohydrate/insulin (Wall et al., 2011). However, LCLT has genuine exercise recovery benefits through mechanisms likely related to reduced oxidative stress and improved blood flow. ALCAR has a separate evidence base for cognitive support, leveraging its ability to cross the blood-brain barrier. The TMAO concern is worth noting but remains debated — regular exercisers appear to have different gut microbiome profiles that may mitigate TMAO production.