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    July 23, 2015 -- Lisa Baxter carefully reads food ingredient labels when she buys groceries. She carries around a list of things she can and can’t eat, and she has to be extra cautious of food ingredients using the word “phosphate.”

    Phosphates leave a metallic taste in her mouth, and they make her very itchy.

    “I feel like I have fleas,” says Baxter, 52, a social worker from Queens, N.Y. She’s been living with kidney disease for about 20 years. “I itch from the bottom of my feet through the middle of my hands.”

    Baxter gets dialysis three times a week, and she knows that phosphates could make her even sicker. People with kidney disease have a hard time breaking down these minerals, which get added to many processed foods to boost their flavor. Eating too much can trigger bone loss and lead to life-threatening problems like heart disease.

    “I’ve seen how devastating phosphorus can be,” says Geoffrey Block, MD, associate clinical professor in medicine at the University of Colorado Health Sciences Center. He’s referring to the mineral that phosphates are made from, and he's been researching its impact on the body for 20 years. “I’ve seen many [kidney disease] patients with amputated limbs.”

    Even in healthy people, there is some evidence that eating too much phosphorus might cause problems, although the data isn't definitive. An FDA researcher and a European health safety commission that studied phosphorus have both called for more research on its potential health effects.

    “There is accumulating evidence that both the high intakes and the poor balance of intake with other nutrients may place individuals at risk of kidney disease, bone loss, cardiovascular disease, and other chronic health conditions,” concludes a study written in part by Mona Calvo, an expert at the agency’s Center for Food Safety and Applied Nutrition. The study also says that the evidence “remains weak.” [Her study does not reflect FDA policy, and the agency did not make her available for comment.]

    Too Much May Be Tied to Trouble

    Phosphorus is found naturally in dairy, meat, and plants. It's needed to help cells work properly. Phosphates enhance flavor and moistness in deli meats, frozen food, cereals, cheese, and baked goods, as well as in sodas and prepared iced tea mixes.