This is a hard subject and people really get offended.
Eat a LOT of vegetables, Personally, I like Prunes and Plums, drink Prune Juice.
Apples, Grapes, Broccoli, all very filling.
Yogurt, REAL yogurt, seven strain, look up the label on Chobani if you don't have that in Michigan, Not sure if Farmer Jack has that or not, been several years since...
Probiotics, watch the film Probiotic America, you only need to watch the first 15 minutes to understand.
http://probioticamerica.com/presentation_23_13.php
If he has multiple levels, and you have the cash, go for a trip to Europe, (you can use your 401K, and get reimbursed) I went to German Spine Inst, there are others on here that have gone to other places, all have good references.
They can do multiple level ADR there (in Europe, Spain, UK, Germany)