Yes, L-glutamine and to a lesser extent aloe vera have helped my brain fog and what I assume is leaky gut.
Don't rule out candida/yeast playing a role in the brain fog though. The yeast gives off toxic byproducts, (aceltyhyde or however you spell that) that are a lot of work for your body to get rid of.
I am seeing a little bit of improvement by stepping away from the candida diet and actually eating a lot more fruit and little to no fat. I know this is not the normal route, but worth a shot for people who have tried all the regular protocols without success.