Twenty years ago I read the book “Why Stomach Acid is Good for You” by Jonathan Wright. I remember it as very helpful and it does talk about low stomach acid. I believe that’s it’s primary topic(I read it so long ago it’s hard to remember) what I do know is that gerd has not been a problem since then when I started eating very low carb. Before that I had taken either Prilosec or Nexium every day. I could not go a day without them. The book is available on Amazon.