I believe a pre-biotic, Lactulose, has multiple benefits for those with GERD that are taking ppi's and are also having problems with constipation.
Start with a small dose, as individual tolerance and symptoms vary and discuss with your primary health carer or GP before use.
There are two main benefits for those taking regular ppi's,
1, It increases acidity in the colon which helps increase mineral uptake.
2, It can reduce pathogens by increasing the number of beneficial gut bacteria.