Glutamine is fairly effective to heal leaky gut. Its main plus is that it helps reduce problems associated with sugar sensitivity and sugar allergies.
Inulin and foods with FOS are an easy way to help heal leaky gut; get some inulin (aka miracle fiber) and sprinkle it on the foods that you eat (or in foods that you bake). It heals leaky gut as well.
Grape bitters (or other bitters)
Digestive enzymes (I take one called pro-gest)
*And there are more!
Another factor, reduce inflammation:
(fermented cod liver oil)
or anti-inflammatory foods (broccoli, salmon, etc)