The hidden pop of soda

Illustration of food for thought

There may be more than empty calories in that can of soda. A high dietary intake of phosphate—a common additive found in soda and other processed foods­—may promote skin cancer, Emory researchers have found.

Phosphate occurs naturally in eggs, beans, and some vegetables, but it is added to many processed foods, such as frozen pizza, deli meats, and ice cream, to improve texture and taste and prolong shelf life.

The researchers applied dimethylbenzanthracene, a carcinogen found in cigarette smoke, to the skins of mice, followed by another chemical that stimulates cell growth. Mice fed a high-phosphate diet had 50% more skin papillomas than mice fed a low-phosphate diet. The high-phosphate diet was the equivalent of 1,800 mg. for people, and the low-phosphate diet, 500 mg. The recommended daily allowance for adults is 700 mg., though their average daily intake is 1,334 mg.

“Phosphate in the diet hasbeen studied previously for its effects on bone formation and bone breakdown, as well as by cardiologists and kidney specialists,” says Emory endocrinologist George Beck. “But outcomes and end points having to do with cancer have not been looked at.”

Beck and his colleagues found that in the presence of high phosphate, bone cells divide more quickly and produce more cancer-related proteins, including osteopontin, a protein linked to the breakdown of bone. They also found that high phosphate in a mouse’s diet increases the level of osteopontin in the blood.

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Emory Medicine Summer 2010