Food Additive Jump-Starts Lung Cancer

By: Sylvia Booth Hubbard

Alarming new research shows that inorganic phosphates, which are commonly added to many processed foods, may accelerate the growth of lung cancer tumors and even trigger the development of tumors in people predisposed to lung cancer. Phosphates are routinely added to food products such as cheeses, meats, bakery products, and beverages in order to improve texture and increase water retention.


The research, which was conducted at Seoul National University and appears in the January issue of the American Thoracic Society’s magazine American Journal of Respiratory and Critical Care Medicine, was carried out with mice. Study leader Myung-Haing Cho, D.V.M., Ph.D., said, “Our study indicates that increased intake of inorganic phosphates strongly stimulates lung cancer development in mice, and suggests that dietary regulation of inorganic phosphates may be critical for lung cancer treatment as well as prevention.”


Cancer of the lung is the most lethal of all cancers, and non-small cell lung cancer (NSCLC) is the form it takes more than 75 percent of the time. Previous research has shown that 9 out of 10 cases of NSCLC were linked to the activation of signaling pathways in lung tissue, and the new research shows that inorganic phosphates can stimulate the same pathways. “Lung cancer is a disease of uncontrolled cell proliferation in lung tissues,” said Dr. Cho, “and disruption of signaling pathways in those tissues can confer a normal cell with malignant properties.”


Lung cancer-model mice used in the study received a four-week diet of either 0.5 or 1.0 percent phosphate, which is an amount that simulates modern human diets. When the effects of the two levels of dietary phosphates were analyzed, the diet higher in phosphates, according to Dr. Cho, “caused an increase in the size of the tumors and stimulated growth of the tumors.”


Dr. Cho said that while the 0.5 amount of phosphate was defined as close to the equivalent “normal” amount in the average human diet today, the real-world equivalent may be closer to the 1.0 amount or may even exceed it. “In the 1990s, phosphorous-containing food additives contributed an estimated 470 mg per day to the average daily adult diet,” Cho said. “However, phosphates are currently being added much more frequently to a large number of processed foods, including meats, cheeses, beverages, and bakery products. As a result, depending on individual food choices, phosphorous intake could be increased by as much as 1000 mg per day.”


Future studies will seek to determine “safe” levels of inorganic phosphates. Future research will also address possible involvement of phosphates in the development of lung cancer in smokers, since up to this time no one has known why some smokers develop lung cancer while others never do.