I take Jarrow's 250mg Acetyl L- Carnitine every morning. It is one of my most important supplements. I only take 1 because when I tried increasing to 2 it effected my sleep. I am not a great sleeper and many things cause me sleep problems. Jarrow is the only reputable brand I've found that makes that low a dose. When I began taking it I felt an energy boast and desire to get things done. I don't feel that same type of boost now but if I stop taking it I have a decrease in energy. That's how I know it's still working for me.