Acetyl-L-carnitine is a modified form of the amino acid derivative L-carnitine. The addition of an acetyl group makes it a slightly different substance, which is often used in supplement form.

Amino acids are the small building blocks of proteins. There are twenty that are commonly found in food. Some are considered essential, which means they are not produced by the body and must come from your diet.

L-carnitine, from which acetyl-L-carnitine is derived, naturally occurs in foods such as meat and dairy products. Vegetarian sources usually contain less of it.

No, acetyl-L-carnitine itself is not an essential amino acid. It is a derivative, or a derived form, of the amino acid L-carnitine.

Taking it at a time when you have not had protein-rich food, for example half an hour before or two hours after a meal, is intended to ensure that the absorption of the supplement is not influenced by other nutrients present.