It is a question I wish science had some answers for.

Though based on firsthand experience I will say that prevention of loss of ability is generally a more realistic and achievable goal than restoring lost ability.

If you want to know what foods have been helpful to me, personally, in dealing with a different genetic disorder, I could answer that question to some degree. Though I generally dislike trying to do so in a comment on a forum, in part because it's something I have been working on for nearly twenty years, so an off-the-cuff comment generally isn't going to be an adequate explanation.