acetyl-l-carnitine interaction with levothyroxine L-carnitine promotes the synthesis of acetylcholine. During hypoxia, Acetyl L-Carnitine

Additionally, consumption of nuts, tea, moderate amounts of alcoholic beverages, and food rich in vitamin E and fiber has been associated with a reduced risk of heart attack

This is far from a dealbreaker for a supplement that has so much to offer, but its worth noting if youre especially sensitive to flavor

Food and Drug administration

In this study, 80 participants were randomly assigned to receive either L-tyrosine (2000 mg), L-theanine (200 mg), or a placebo before undergoing a high-stress scenario involving a virtual reality-based active shooter training drill and cognitive challenges like the Stroop test and mental arithmetic

Jung et al, 2017