Based upon you brief description of your disorder, the back pain most likely is caused by the spondylolisthesis. You are very focused on nutritional treatment for this disorder but as I have stated before, the disc is relatively avascular and fractures (if isthmic) are not affected by good nutrition. Fractures are however influenced negatively by poor nutrition (diabetes, alcoholism, starvation).
I would assume by your focus on nutrition that your food intake is good.
This is most likely a mechanical problem of the spine and you would be better focused on rehabilitation than on supplements.
Dr. Corenman