Acetyl-L-Carnitine is probably the most useful form of Carnitine there is. It can cross the blood-brain barrier, which makes ALCAR good for nootropic purposes. 

You’ll commonly find ALCAR in products such as nootropics, fat burners, pre-workouts, and as a standalone as well.

L-Carnitine is well-known and widely used ingredient in fat burners. While L-Carnitine is a debatable ingredient for the purpose of fat loss, it needs more research to be considered a “proven” fat burner. L-Carnitine is widely known to be a transporter of fatty cells to be used as energy, which is why it is so commonly put in fat burning products.

As for nootropic/pre-workout purposes, it has more promise. One of the studies was done on the elderly which showed a reduction in physical and mental fatigue. Another study on children with ADHD showed that Carnitine supplementation decreased attention problems and aggressive behavior.  

Another use for ALCAR supplementation may be for depression. One study showed that people with depression had on average a lower ALCAR levels.

There is at least one study​​​​​ showing that ALCAR may be good for blood pressure and blood sugar.

ALCAR is usually added in with fat burners, nootropics, and pre-workouts.

It is commonly found in stim-based and stim-free fat burners. So you’ll find it paired with ingredients such as Caffeine, Yohimbine, Synephrine, Higenamine and more. 

As for nootropics, you’ll find it paired with ingredients such as Alpha GPC, Huperzine A, and L-Tyrosine. 

ALCAR can cause some side effects including stomach upset, nausea, vomiting, dry mouth, headache, and restlessness. 

The recommended dosage of ALCAR is 630mg-2,500mg per day.

The following products contain Acetyl-L-Carnitine at the recommended dosage, and are recommended supplements for Fitness Informant: