Inorganic phosphate, an additive and preservative used in up to 70 percent of food in the American diet, may be contributing to couch potato behavior.

“We should not consume more than 700 milligrams of inorganic phosphate per day, but about one-third of people consume three to four times that amount,” said Dr. Wanpen Vongpatanasin, Professor of Internal Medicine and Director of the Hypertension Fellowship Program at UT Southwestern. “Like any nutritional ingredient, too little phosphate is harmful, but too much is also harmful.”

The study describing the adverse effects of excess consumption of phosphate is published in the journal Circulation.

Phosphate is plentiful in fruits and vegetables in its organic form, which does not cause problems because it is not absorbed. However, the body readily absorbs inorganic phosphate, and most people are consuming far too much of it. For example, cola drinks, processed meats, and prepared frozen foods typically contain this additive.

When the researchers studied mice fed a high-phosphate diet, they found measurable changes in their ability to exercise. In addition, the study analyzed physical activity data from participants in the Dallas Heart Study and verified that their responses to phosphate were similar. Higher phosphate levels were linked to reduced time spent in moderate to vigorous exercise, while sedentary time increased as phosphate levels climbed.

Since inorganic phosphate is widely used in the food supply, the UT Southwestern research team concluded that more studies are needed to further define the broader health impact of this substance.