Phosphorus is added to many processed foods to enhance their flavour and extend their shelf life. High levels of phosphorus are also naturally found in animal, dairy and vegetable proteins, said study leader Dr Alex Chang, of Johns Hopkins University in Baltimore in the US.
The study of nearly 500 overweight or obese adults enrolled in a healthy-lifestyle program found that a shrinking waistline and lower consumption of dietary phosphorus were associated with reduced levels of protein in the urine (albuminuria), which is an early sign of kidney disease.
After six months, participants' waistlines shrunk an average of 1.7 inches and they had a 25% reduction in urine protein. The researchers also found that a 314-milligram reduction in phosphorus excretion resulted in an 11% decrease in urine protein.
The study appeared in the American Journal of Kidney Diseases.
What have other studies suggested?
Other studies have suggested that weight loss may slow kidney disease progression, but this is the first research study to support losing belly fat and limiting phosphorus consumption as a possible way to prevent kidney disease from developing in the first place, Dr Joseph Vassalotti, chief medical officer at the National Kidney Foundation, said in a foundation news release.
"A good rule of thumb is that if the food comes in a package, it's likely to be high in phosphorus," he said. "Approximately 90% of phosphorus additives are absorbed by the body."
More information on phosphorus
To limit phosphorus consumption, look for the root letters "PHOS" on food labels. But phosphorus isn't always listed on food labels, Vassalotti said, so you need to know likely sources. They include:
- Processed foods such as dark colas, cereals and flavoured waters.
- Dairy products such as cheese, milk, cream, ice cream and yoghurt.
- Animal protein such as deli meats, organ meats, meat tenderisers, oysters and sardines.
- Dried beans, lentils, peas, nuts and seeds (including peanut butter and other nut butters), cocoa (including chocolate-based drinks and puddings).