I read that cola based drinks are not good for CKD. Are all dark sodas cola based? What sodas can I safely drink - root beer, drinks with citric acid?

Colas or dark sodas are a problem for people on dialysis and people with very poor kidney function (generally Stage 4 or 5 chronic kidney disease (CKD). These sodas contain an excessive amount of phosphorus and this should be limited in advanced kidney disease. Whether they are caffeine free or regular is not important. Phosphorus may accumulate in patients with advanced CKD and create bone problems. The metabolic bone disease in CKD is known as secondary hyperparathyroidism and excessive phosphorus intake can make this worse. Clear sodas do not contain as much phosphorus and are better if a person with advanced kidney disease wants to drink a soda. I, personally, recommend that you drink water.