L-Carnitine
L-carnitine has FDA GRAS notices for various uses; tolerated at typical doses. NIH ODS notes that gut microbiota convert L-carnitine to TMAO, which has been associated in dose-dependent observational studies with increased cardiovascular disease risk; some long-term supplementation studies have shown mixed results.
What it is
L-carnitine — quaternary ammonium compound naturally synthesized from lysine and methionine; transports fatty acids into mitochondria.
Functional ingredient/supplement; nutrient added to infant formula and energy/sports products.
Why it's flagged
- gut microbial conversion to TMAO (cardiovascular signal in observational studies)
- GI symptoms at high doses
What regulators actually say
"Researchers have found that L-carnitine is metabolized by intestinal microbiota to trimethylamine-N-oxide (TMAO), a proatherogenic substance associated with increased cardiovascular disease risk."
Regulatory status
United States — FDA
GRAS for several uses (multiple GRAS notices); permitted in infant formula.
European Union — EFSA
Permitted as a nutrient; EFSA has reviewed L-carnitine in food supplements.
Scan it before you buy it
Get Ube on iOS or Android — point at any barcode, see what's actually in there.
Get the app