Thursday, January 01, 2009

Food Phosphates Might Spur Lung Cancer

Food Phosphates Might Spur Lung Cancer
Accelerated growth of tumors seen in study
By Ed Edelson, HealthDay Reporter

A diet rich in the inorganic phosphates found in many natural and processed foods accelerated the growth of lung cancers in test subjects, South Korean researchers report.

"Our study suggests that dietary regulation of inorganic phosphates may be critical for lung cancer treatment as well as prevention," Myung-Haing Cho, lead author of a report in the first January issue of American Journal of Respiratory and Critical Care Medicine, said in a statement.

Natural sources of dietary phosphates include leafy vegetables, fruits, meats and poultry products. Phosphates also are added to a number of foods, including baking powder, carbonated cola drinks, ice cream, bread, rolls, macaroni, fruit jellies and preserves. Food phosphates are listed by the U.S. Food and Drug Administration as GRAS -- generally recognized as safe -- with no limits on their use.

The South Korean study was done with two subjects, one genetically inclined to have lung cancer, the other with induced lung cancers. They were fed either diets containing phosphates in roughly the same amounts found in human diets or phosphates at twice that level. After four weeks, more and larger lung cancers were found in the subjects given the higher-phosphate diets, the report said.

Phosphates appear to activate a metabolic pathway that stimulates the growth of the lung tumors, the researchers said. There is "good scientific rationale" for believing that phosphates can stimulate the growth of lung cancers and other tumors, Heffner said. But for lung cancer, he said, "the first thing is not to smoke." Genetics can also play a role in risk, Heffner added, since "some smokers get lung cancer, and some don't."

"I'll be more cautious about inspecting foods I ingest for phosphate addition, trying to keep dietary phosphate ingestion in the healthy range," he said.

Studies are planned in South Korea to determine what the healthy range is, the researchers stated. In the 1990s, phosphate-containing food additives contributed an estimated 470 milligrams a day to the average adult diet. Their wider use has increased intake by as much as 1,000 milligrams a day, equivalent to the higher dose given to the rats in the experiment, Cho noted.

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