Treating leaky gut should start at the same time you begin treating for candida. It should include repairitive treatments (glutamine, colostrum, bone broth, slippery elm) as well as avoiding those things that cause leaky gut (gluten, aspirin, advil,alcohol,etc.). After the leaky gut is healed you can drop the reparitive treatments but of course you must continue to avoid anything that is causitive for leaky gut indefinitively.
I never was tested for the MTHFR gene defect. I probably don't have that problem because I would know by now if I did since it is a serious health issue.