Forget L-glutamine because it will not fix Increased Digestive Permeability aka Leaky Gut, a term I dislike because it is misleading.
Your wasting your time taking it because it will not make any difference. L-glutamine for Leaky Gut is promoted by the Psychology crowd who [wrongly] believe that you can think yourself well and solve it by believing your doing something positive. It does not work because it cannot work, IDP is caused by a bacteria infection which are highly antimicrobial resistant and L-Glutamine will have zero effect against them. No regular Antibiotics can destroy them. As soon as the bacteria are destroyed, the digestive system heals within a few minutes WITHOUT taking ANY L-Glutamine!!! That is how useless it is.