what are the side effects of taking l carnitine bright and the dark sides L-carnitine supplementation: a systematic review | Journal of the International Society of Sports Nutrition Carnitine: the claims and why

Mutations or inhibitions of human FMO3 that prevent TMAO production can lead to the accumulation of TMA, which is excreted in excess in urine, sweat, and breath, smelling like rotten fish (Zeisel and Warrier, 2017)

This dose failed to increase her breastmilk carnitine concentration, with a persistently low concentration of 3.4 mg/L (21 micromoles/L) before supplementation and after 18 days of supplementation.[1] The carnitine concentration was measured in the breastmilk of 27 normal mothers who were not taking carnitine as a supplement

Ou SM, Tsai MT, Chen HY, Li FA, Tseng WC, Lee KH, et al

These effects were associated with the inhibition of NF-B nuclear translocation and reduced phosphorylation of B and mitogen-activated protein kinases, including p38, extracellular signal-regulated kinases 1 and 2 (Erk 1/2), and c-Jun N-terminal kinase (282)