Acetyl-L-Carnitine is produced in small amounts in the body. Although deficiencies are rare, vegetarians could be at risk because significant dietary sources that contain Acetyl-L-Carnitine are few. An ALC deficiency might result in muscle fatigue, cramping, tiredness and heart irregularities.

Some studies indicate ALCAR may support healthy cardiac function owing to its antioxidant and anti-apoptotic activity. Acetylcarnitine and carnitine play important roles in the human body. These nutrients shuttle acetyl groups and fatty acids into mitochondria for energy production. Without carnitine, fatty acids cannot easily enter into mitochondria. The acetyl group is used to form acetyl-CoA, the most important intermediary in the generation of energy from amino acids, fats, and carbohydrates. Therefore it serves as an energy reservoir of acetyl groups and both nutrients help improve energy production. The acetyl group is also used to make the important brain chemical acetylcholine. Some studies suggest that perhaps acetyl l-carnitine can even act as a neurotransmitter itself. This nutrient is sometimes abbreviated as ALC or ALCAR.
Individuals taking carnitine pills notice an increase in physical energy but not as much mental energy. Acetyl L-carnitine has a more immediate and noticeable mental effect than carnitine because it crosses into the brain much effectively and swiftly. The mind boosting effect of ALC is often noticed within a few hours, or even within an hour. Most people report feeling mentally sharper, with more mental stamina, better focus and being more alert. Some observed a mild mood enhancement.