l carnitine overdoese L-Carnitine | Linus Pauling Institute L-Carnitine for Cutting vs Bulking:

Moreover, given that its toxic metabolite, trimethylamine-N-oxide (TMAO), facilitates low-density lipoprotein (LDL) uptake into the arterial wall, promoting atherosclerosis, there is presently little evidence to support the long-term safety of L-carnitine supplementation

NF-B not only induces canonical pro-inflammatory cytokines (TNF-, IL-6, pro-IL-1) but simultaneously up-regulates facilitative glucose transporter, metabolically locking macrophages, DCs and activated T cells into a glycolytic, NO-rich phenotype that fuels chronic mucosal inflammation (110112)

Headaches: Headaches are a less common side effect but may occur in some individuals

Ramadan AA, et al

Moreover, the Firmicutes type has a huge number of bacteria known for their ability to produce short-chain fatty acids [50]