Do you train intensely? (You’re reading IRON MAN, so chances are you train very hard.) To get the best results from your workouts, it’s a good idea to take supplemental glutamine. You probably already know that it boosts the immune system, but get this: It’s also been shown to increase the amount of L-leucine in muscle tissue. Current research shows L-leucine emerging as the key essential amino acid in anabolic reactions. Try taking three grams before and after your workouts.