Dietary advice aside the major means of removing toxins from the body in patients with kidney disease, which is dialysis is not particularly helpful in patients as phosphate is very slow to be removed by conventional dialysis. The only modality that seems to have a profound effect on phosphate removal is long nocturnal hemodialysis, the benefit here is that phosphate removal is primarily tied to the the length of time that you are dialysed.

So if phosphate is present in many foods and beverages, particularly sodas and conventional dialysis does not perform well in its removal, then we end up with phosphate accumulation in dialysis patients. Since not everyone has access to nocturnal hemodialysis the answer would seem to be reducing phosphate intake.

However even with dietary manipulation phosphate has been slowly creeping back into the diet of patients on dialysis through an unsuspected mechanism.

Food additives are substances added to food in order to preserve and give longer shelf life in most cases. Frequently the phosphate content of the food additive is not available to the dietician when planning the diet sheet of the dialysis patient and as such the dietary advice may have very little effect on overall phosphate intake. Proper labelling of foods would of course solve this problem but this is not yet a requirement.

But what exactly does high phosphate levels cause?

The problem with phosphate is that it is one of the substances that make up bone and as such it is regulated by a hormone known as PTH. High phosphate stimulates PTH levels, elevated PTH somehow affects the cardiovascular system contributing to increased stiffness of the blood vessels and increased risk of cardiovascular disease.

What can be done?

Focused education on the need to be aware of the phosphate content of food may result in lower phosphate intake if alternative preservative and additive food sources can be accurately identified. In other words educate, create the need and someone will provide the service of low phosphate food.

A recent review of the phosphate content of food is available here