Enhanced Foods: Hidden Phosphorus and Sodium in Foods Commonly Eaten

PHOSPHATE ADDITIVES in foods have become a mainstay in our food supply. In 1990, additives contributed an estimated 470 mg/day to the American diet.1 With the insurgence of these new foods, additives could now contribute up to 1,000 mg/day of phosphorus, depending on one’s food choices.2 Products commonly enhanced with phosphorus additives include restructured meats (chicken nuggets and hotdogs), processed and spreadable cheeses, “instant” products (puddings and sauces), refrigerated bakery products, and beverages.1

Enhanced meats can also contribute unwanted phosphorus and sodium to the diet. Enhanced meats are significantly higher in sodium than fresh, unadulterated meat. Enhanced meats contain over 300 mg per 3-oz serving, compared with most fresh meats, which contain approximately 50 to 75 mg of sodium per 3-oz serving.

Enhanced foods are a concern not only for the general population but also for chronic kidney disease (CKD) patients. Phosphorus additives are highly absorbable. In a typical mixed diet containing grains, meat, and dairy, only 60% of the dietary phosphorus is absorbed, whereas phosphoric acid and various polyphosphates and pyrophosphates are almost 100% absorbed.3 Diets higher in these inorganic salts will result in higher phosphorus absorption, which can aggravate hyperphosphatemia in CKD patients.

Authors Murphy-Gutekunst, Barnes, and Uribarri, in previously published Journal of Renal Nutrition Product Updates, outline the challenges in tracking down the nutrition information provided in these phosphate-enhanced products. Their diligent efforts have resulted in the patient education piece provided herein.4, 5, 6 Issues highlighted include the following: (1) manufacturers are no longer required to list the phosphorus content on nutrition labels, (2) nutrition analysis information is not readily available to customer service representatives, (3) nutrition analysis information is not disclosed or is considered proprietary, and (4) meat managers may not know for certain if the meat they receive from their central supplier has been enhanced.

This is a call to action to nephrology clinicians and CKD patients alike. Patients should inquire about enhanced meats and check nutrition and meat labels closely. Clinicians should work with local grocers and/or food chains to identify a list of enhanced meats and share this information with their patients. In addition, we should educate and re-educate our patients on reading nutrition labels. The NKF/CRN has an excellent patient education piece on label reading that can be found at www.kidney.org.7 An informed patient is better equipped to make better food choices that may result in decreasing complications associated with mineral metabolism abnormalities.

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