L-Glutamine will NEVER, and I repeat NEVER fix leaky gut. It's a sad fact that people believe this information. You could take 100's of grams of it and it will not fix anything that I can guarantee 100%. I will bet anyone that it will not fix leaky gut.
People with Increased Intestinal Permeability Syndrome aka Leaky Gut have an increased requirement for Glutathione and therefore some Glutamine will help in this along with the other required nutrients and amino acids such as cysteine/cystine, Glycine and Methionine.