What Is Sodium Phosphate?

FDA rules at 21 CFR 182.1778 list sodium phosphate, in mono-, di- and tribasic forms, as generally recognized as safe when used in accordance with good manufacturing practice. USDA meat and poultry rules allow phosphates such as disodium phosphate to decrease the amount of cooked out juices, limited to 0.5 percent of phosphate in meat food products and 0.5 percent of total product in poultry products, and the FDA's standard for pasteurized process cheese lists monosodium, disodium and trisodium phosphate among permitted emulsifying agents.

Phosphate additives matter most for kidney disease. NIDDK says damaged kidneys cannot remove phosphorus from the blood as well as healthy kidneys, so it can build up in people with chronic kidney disease, harming blood vessels and making bones thin and weak, and that phosphorus additives are the primary source of phosphorus for many people. It advises people with chronic kidney disease to limit or avoid packaged and processed foods and drinks with added phosphorus, such as deli meats and flavored drinks. The National Kidney Foundation says phosphorus from food additives is completely absorbed and advises looking for PHOS in ingredient lists to find them.

As a medicine, sodium phosphate is also used to clean out the colon. The FDA-approved label for a prescription oral sodium phosphate bowel prep carries a boxed warning about rare, serious reports of acute phosphate nephropathy after colon cleansing before colonoscopy, including some cases of permanent kidney impairment and long-term dialysis. In a 2009 letter, the FDA said it had continued to receive reports of acute kidney injury with both prescription and over-the-counter oral sodium phosphate products since a May 2006 alert.