PPI's reduce stomach acid to almost nothing, many of your minerals don't get digested and absorbed properly. Low stomach acid can also lead to other conditions which then disrupt and/or cause inflammation of the duodenum and both the upper and lower intestines. So of course these PPIs, over time, cause all sorts of problems.
Go Amazon and search for the book "Why Stomach Acid Is Good for You: Natural Relief from Heartburn, Indigestion, Reflux and GERD" (by Jonathan Wright, MD), it explains this in great detail. It also tells you how to get off of PPI's and fix your GERD. It worked for me and at age 50 I feel better now than I have in 30 years. You have no idea how much better you feel when your food, vitamins, and meds are properly digested.