Over the last few days I’ve gone down a rabbit hole while researching the use of various amino acid supplements to modulate neurotransmitter levels, improve mood, and influence mental states in specific ways (increase concentration, motivation, reduce anxiety, etc.). One supplement that’s of particular interest to me is acetyl-l-carnitine (often abbreviated as ALCAR). I first became aware of ALCAR from this now-famous 2002 anti-aging animal study in which old mice regained their youth after being fed a combination of acetyl-l-carnitine and alpha-lipoic acid with their chow.

But there are possible risks to consuming supplemental acetyl-l-carnitine. Low blood levels of acetyl-l-carnitine are associated with negative outcomes, including depression (according to this recent Stanford study), so we want to make sure we get enough. Can we just eat more read meat (which contains substantial amounts of l-carnitine) or take supplemental ALCAR to bolster our blood levels? There’s always a catch. In this case it’s TMAO, a dangerous chemical that promotes hardening of the arteries. Various pathogenic gut bacteria convert dietary and supplemental l-carnitine to TMAO.

Well that’s a drag.

So are there ways to kill off these bad bacteria, or inhibit their metabolic processes so that l-carnitine can be absorbed into the bloodstream, and less TMAO is created?