Patients with end-stage renal disease (ESRD) who participated in an education program to limit their intake of phosphorus-containing food additives lowered their blood levels of the chemical, according to a study in the February 11 issue of JAMA, the Journal of the American Medical Association.
Individuals with moderate to severe kidney disease have an impaired ability to excrete phosphorus, and as a result, they tend to develop hyperphosphatemia (abnormally high concentration of phosphates in the blood), especially if their intake of phosphorus is high. Elevated serum phosphorus levels are associated with an increased risk of death and illness, with levels greater than the 5.5-mg/dL level recommended by practice guidelines associated with a 20 percent to 40 percent increase in the risk of death among patients with ESRD. In addition, hyperphosphatemia appears to be involved in the development of a number of health risks, including heart disease and bone disease, according to background information in the article.
To prevent hyperphosphatemia, patients with ESRD limit their intake of foods that are naturally high in phosphorus such as meats, dairy products, whole grains and nuts. However, phosphorus-containing additives are increasingly being added to processed and fast foods, particularly meats, cheeses, baked goods and beverages. The effect of such additives on serum phosphorus levels is unclear.
Catherine Sullivan, M.S., R.D., L.D., of MetroHealth Medical Center and Case Western Reserve University, Cleveland, and colleagues tested an educational intervention to reduce the intake of additive-containing processed and fast foods to determine if there is a causal relationship between additive consumption and hyperphosphatemia among patients with ESRD. The study included 279 patients with elevated baseline serum phosphorus levels (greater than 5.5 mg/dL). About half of participants reported eating fast food more frequently than once a week. Intervention participants (n = 145) received education on avoiding foods with phosphorus additives when purchasing groceries or visiting fast food restaurants. Control participants (n = 134) continued to receive usual care.
At the beginning of the trial, the average serum phosphorus level was 7.2 mg/dL among intervention participants and 7.1 mg/dL among control participants. After 3 months, serum phosphorus levels declined by 1.0 mg/dL among intervention participants and by 0.4 mg/dL among control participants, a difference of 0.6 mg/dL. Intervention participants also had significantly larger increases in reading ingredient lists and nutrition facts labels compared with control participants.