Soft drinks have no effect on the kidneys of healthy people. However, many patients with advanced kidney disease are instructed to avoid dark-colored sodas. The basis for this recommendation is not to protect the kidneys, but to prevent problems related to the high-phosphorus levels found in patients with advanced kidney disease.
Kidneys and Phosphorus
The kidneys regulate the amount of phosphorus in the blood. When healthy people consume large amounts of phosphorus, the kidneys excrete the excess into the urine. The kidneys of people with advanced kidney disease are less able to perform this function, which is why nephologists routinely measure serum phosphorus levels. If the patient's phosphorus levels become elevated, a low-phosphorus diet may be indicated.
Phosphorus and Soda
Some soft drinks are high-phosphorus foods. The USDA nutrient database indicates that a 12-oz. can of cola has 37mg of phosphorus. A comparable serving of diet cola, including "pepper type" sodas, has 32mg of phosphorus. Clear lemon-lime sodas and ginger ale have none. If you have elevated phosphorus levels, the National Kidney Foundation suggests that you avoid dark-colored soft drinks.
Consequences
The National Kidney Foundation explains that excess phosphorus causes changes in your body that pull calcium from bone. While this is particularly dangerous for growing children with kidney disease, it also is hazardous for adults. The renal osteodystrophy that results leaves patients vulnerable to bone fractures. Moreover, high calcium levels in the serum can be deposited in blood vessels, lungs, eyes and other tissues.
Treatment
In addition to avoiding high-phosphorus soft drinks, kidney patients with high phosphorus levels should also avoid organ meats, dried peas and beans, beer and chocolate. Nephrologists often recommend a drug called a phosphorus binder. Patients take phosphorus binders with meals. The drug prevents some of the phosphorus in the food from entering the blood stream.
References
- USDA National Nutrient Database: Carbonated Beverage, SPRITE, Lemon-Lime, Without Caffeine
- USDA National Nutrient Database: Carbonated Beverage, Cola, Contains caffeinC
- USDA National Nutrient Database: Carbonated Beverage, Low Calorie, Cola or Pepper-Type, Low Calorie, Cola or Pepper-Type,
- USDA National Nutrient Database: Carbonated Beverage, Ginger Ale
- National Kidney Foundation: Phosphorus and Your CKD Diet
- National Institute for Diabetes and Digestive and Kidney Diseases; Chronic Kidney Disease-Mineral and Bone Disorder; February 2009
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