Common food additive found to increase risk and speed spread of lung cancer

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Public release date: 29-Dec-2008

http://www.eurekalert.org/pub_releases/2008-12/ats-cfa122208.php

Contact: Keey Savoie

ksavoie@...

American Thoracic Society

Common food additive found to increase risk and speed spread of lung cancer

New research in an animal model suggests that a diet high in inorganic

phosphates, which are found in a variety of processed foods including

meats, cheeses, beverages, and bakery products, might speed growth of

lung cancer tumors and may even contribute to the development of those

tumors in individuals predisposed to the disease.

The study also suggests that dietary regulation of inorganic phosphates

may play an important role in lung cancer treatment. The research, using

a mouse model, was conducted by Myung-Haing Cho, D.V.M., Ph.D., and his

colleagues at Seoul National University, appears in the first issue for

January of the American Journal of Respiratory and Critical Care

Medicine, published by the American Thoracic Society.

" 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, " said Dr. Cho.

Lung cancer is the number one cause of cancer deaths in the world and is

also the most frequently diagnosed solid tumor. Non–small cell lung

cancer (NSCLC) constitutes over 75 percent of lung cancers and has an

average overall 35-year survival rate of 14 percent. Earlier studies

have indicated that approximately 90 percent of NSCLC cases were

associated with activation of certain signaling pathways in lung tissue.

This study revealed that high levels of inorganic phosphates can

stimulate those same pathways.

" Lung cancer is a disease of uncontrolled cell proliferation in lung

tissue, and disruption of signaling pathways in those tissues can confer

a normal cell with malignant properties, " Dr. Cho explained.

" Deregulation of only a small set of pathways can confer a normal cell

with malignant properties, and these pathways are regulated in response

to nutrient availability and, consequently, cell proliferation and growth.

" Phosphate is an essential nutrient to living organisms, and can

activate some signals, " he added. " This study demonstrates that high

intake of inorganic phosphates may strongly stimulate lung cancer

development by altering those (signaling) pathways. "

In the study, lung cancer-model mice were studied for four weeks and

were randomly assigned to receive a diet of either 0.5 or 1.0 percent

phosphate, a range roughly equivalent to modern human diets. At the end

of the four-week period, the lung tissue was analyzed to determine the

effects of the inorganic phosphates on tumors.

" Our results clearly demonstrated that the diet higher in inorganic

phosphates caused an increase in the size of the tumors and stimulated

growth of the tumors, " Dr. Cho said.

Dr. Cho noted that while a moderate level of phosphate plays an

essential role in living organisms, the rapidly increasing use of

phosphates as a food additive has resulted in significantly higher

levels in average daily diets. Phosphates are added to many food

products to increase water retention and improve food texture.

" In the 1990s, phosphorous-containing food additives contributed an

estimated 470 mg per day to the average daily adult diet, " he 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. "

" Although the 0.5 percent was defined as close to 'normal,' the average

diet today is actually closer to the one percent diet and may actually

exceed it, " Dr. Cho noted. " Therefore, the 0.5 percent intake level is

actually a reduced phosphate diet by today's scale. "

Dr. Cho said future studies will help refine what constitutes a " safe "

level of dietary inorganic phosphate, with recommendations that will be

easily achievable in the average population.

" The results of this study suggest that dietary regulation of inorganic

phosphates has a place in lung cancer treatment, and our eventual goal

is to collect sufficient information to accurately assess the risk of

these phosphates, " he said.

Heffner, M.D., past president of the ATS, stated that this line of

investigation in animals addresses the complex interactions between host

factors and the environment that underlie cancer in man. " We know that

only some patients who smoke develop lung cancer but the reasons for

this varying risk are unknown. This study now provides a rationale for

funding case-control studies in humans to determine the potential role

of dietary phosphates in promoting cancer. "

--

ne Holden, MS, RD

" Ask the Parkinson Dietitian " http://www.parkinson.org/

" Eat well, stay well with Parkinson's disease "

" Parkinson's disease: Guidelines for Medical Nutrition Therapy "

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