Phosphates artificially added to foods like dairy and cereal products have been associated with sharp increases in blood phosphorous levels that could be harmful to the kidneys, particularly for patients with existing reduced kidney function.

Other studies have shown connections between consumption of phosphate in any form and blood; phosphates can be naturally occurring or added to foods as preservatives, thickening agents, and leaveners. Wadi Suki, MD, of Houston Methodist Hospital, and colleagues evaluated patient data from the National Health and Nutrition Examination Survey (NHANES) spanning 2003–2006 to determine how food consumed impacted blood phosphorous levels.

After controlling for body mass index, kidney function, sex, race, and other factors, the most significant increase in blood phosphate levels were seen in individuals who ate dairy foods and cereal/grain-based foods that contain artificially added phosphates (called “inorganic phosphorous”). A significant increase in blood phosphorous was also observed in those who ate dairy foods without artificially added phosphates, but the effect was less pronounced. When removing kidney function as a control, those with poor kidney function had higher phosphate levels, which indicates that these people had a reduced capability for expunging excess phosphate from the blood.

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The Institute of Medicine (IOM) recommends 700mg of phosphate per day, but many in this study were consuming twice this amount. This could be dangerous for individuals with existing kidney damage or chronic renal disease, the authors note. Currently, the Food and Drug Administration (FDA) does not require food producers to distinguish between naturally occurring and artificially added phosphates on labels and the FDA does not require food producers to quantify the amount of phosphate in the product.

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