There are virtually no syndromes and/or diseases that are not reversible. If he is interested in taking control of his own health [and I sincerely hope he is], the following will give him all the information he needs:
Any of the discourses by Luigi Cornaro (available free online);
Any of the books by Horace Fletcher (available free online);
Any of the writings of Arnold Ehret.
Just like virtually everything else in life, it is all ultimately up to YOU.
You have all my best wishes for a successful journey and resolution,