You’ll find that there are different types of L-carnitine. Because the chemical make-ups vary slightly some work better for specific functions than others: Acetyl-L-Carnitine- the acetyl group basically means a collection of acetyl acid. To put it simply the addition of it to the carnitine aids in good memory function and mental focus. As with other forms of L-carnitine it also increases energy L-Carnitine-L-Tartrate- tartrate, found in nature in some fruits, helps stabilize the L-carnitine. It’s also and effective antioxidant and some studies have shown it aids in more rapid muscle recovery after heavy stress L-Carnitine fumarate- especially good for both metabolizing fat and sending plenty of oxygen to the heart, both valuable properties for athletes D-Carnitine, D-L-Carnitine- only available synthetically and the FDA labels it as an illegal food additive Glycine Propionyl-L-Carnitine (GPLC) – especially good for muscles as it promotes strong blood flow to them and makes up for oxygen lost during workout. Enhances fat metabolism and waste removal from cells http://www.n101.com/info/l-carnitine-guide-what-is-it-and-who-should-use-it/ I have been using acetyl carnitine for a few months at 500mg a day and it helps some. Today i increased this to 1000mg so we will see what happens?? What are other peoples experience with different forms of carnitine? I have seen a few favour fumarate, and im thinking of trying this as well later. cheers!!!