Candida will cause leaky gut.
When the candida turns from yeast to fungus it produces what would be called feelers and they poke through the intestine walls and when you start killing the candida and the feelers die off they pull back through and the leaky gut starts to heal. My leaky gut completly healed after elliminating candida.
You do not have to remove your fillings in order to get rid of candida overgrowth I am living proof. I have 14 fillings and candida overgrowth is gone.