Photo: Australian Kidney Trials Network (AKTN)

US Study Finds Link to Rise in Kidney Cases to Additive Food Phosphates

Photo: Australian Kidney Trials Network (AKTN)

Photo: Australian Kidney Trials Network (AKTN)

Phosphates artificially added to packed dairy and cereal products lead to spike in blood phosphorus levels than naturally occurring phosphates, affecting kidneys and stiffening blood vessels, among other related complications, said a study by Houston Methodist researchers.

“The Institute of Medicine recommends 700 milligrams of phosphate per day and we think that’s a good number. What we were seeing in this study was twice the consumption of that amount for a lot of people. Too much phosphate is concerning to people who are healthy — but it is of special concern to people who already have kidney damage or chronic renal disease,” said Linda Moore, director of clinical research programs for Houston Methodist Hospital’s Department of Surgery.

Phosphates are added to many foods as salts to act as preservatives, thickening agents, and leaveners. In most of the junk food such as potato fries, too much phosphate is found that could affect kidneys. Many studies in the last 10 years have cast pallor over phosphates as a food additive that can lead to kidney failure in particular, said the study.

“Excess phosphorus has adverse effects on patients who already have kidney disease but can also cause kidney problems,” said Wadi Suki, the principal invetigator. “High phosphorus in blood is associated with increased patient mortality, increased blood vessel stiffening, as well as increasing the rate of calcium deposition in heart valves. This calcium comes out of bones and, therefore, weakens bones as well as damaging kidneys.”

Unlike the previous studies, the new study has compared whether phosphates artificially added to food have the same impact as similar amounts of phosphates that are naturally-occurring.

“Pancake and ‘quick bread’ mixes and processed cheeses often contain a lot of inorganic phosphate, so those should be consumed less frequently,” said Moore, a former chairperson of the National Kidney Foundation, Council on Renal Nutrition. “We are seeing an increase in the proportion of Americans who have kidney disease, but no good explanations why.”

Controlling for kidney function and for all other types of foods eaten, one serving of dairy products with inorganic phosphate additives, say 1 ounce of processed cheese will increase the serum phosphorus by 0.07mg/dL and one serving of cereals or grains (a 1/2 cup portion) with added phosphates will increase the serum phosphorus by 0.01mg/dL.

Taking patient data from the US National Health and Nutrition Examination Survey (NHANES) from 2003 to 2006, it was found that the most significant increases in blood phosphate levels occurred in people who ate dairy foods and cereal/grain-based foods that contain artificially added phosphates.

Currently, the FDA does not require food producers to distinguish between naturally occurring and artificially added phosphates on labels. In fact, the FDA does not require food producers to quantify the amount of phosphate at all.

The study was published in the American Journal of Clinical Nutrition.

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