Phosphate is an essential nutrient, however according to Dr Myung-Haing Cho of Seoul National University, whose work is published in the American Journal of Respiratory and Critical Care Medicine, phosphates are being added more commonly to processed food products than in the past. Foods in which they are used to increase water retention and improve texture include meats, cheeses, beverages and bakery goods. Dr Cho says that in the 1990s, phosphorous-containing additives contributed around 470mg per day to the average adult diet.
Now, he says, intake may have risen by as much as 1000mg per day, depending on people’s food choices.
If the results of the mouse study hold for humans too, this could be cause for concern for people with a predisposition to lung cancer, he believes.
Dr Cho and his team worked with mice that were pre-disposed to develop lung-cancer. For four weeks, the mice were fed either a diet with 0.5 per cent phosphate, or a diet with 1.0 per cent phosphate. These ranges were said to be “roughly equivalent to modern human diets”.
At the end of the study, the animals’ lung tissue was examined to determine the effect.
“Our results clearly demonstrate that the diet higher in inorganic phosphates caused an increase in the size of the tumours and stimulated growth of the tumours,” said Dr Cho.
The high phosphate diet was seen to have an effect on Alt signaling and protein translation, as well as stimulate cell proliferation.
“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.”
“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.”
He concluded that the results suggest careful regulation of dietary phosphate “may be critical for lung cancer prevention as well as treatment”.
Studies are ongoing in order to collate sufficient information to assess the risk of phosphates, and refine what constitutes a safe level of intake.
The goal is to make recommendations that will be “easily achievable in the average population”.
Additive scrutiny
Food additives have come under scrutiny in recent times. The European Food Safety Authority, risk assessor to the European Commission, is currently re-assessing the data on all food additives currently allowed in the EU.
A request for comment on how this study may contribute to the assessment of phosphate additives was no answered prior to publication deadline.
Source:
American Journal of Respiratory and Critical Care Medicine Vol 179. pp. 59-68, (2009)Doi: 10.1164/rccm.200802-306OC“High Dietary Inorganic Phosphate Increases Lung Tumorigenesis and Alters Akt Signaling”Authors: Hua Jin, Cheng-Xiong Xu, Hwang-Tae Lim, Sung-Jin Park, Ji-Young Shin, Youn-Sun Chung, Se-Chang Park, Seung-Hee Chang, Hee-Jeong Youn, Kee-Ho Lee, Yeon-Sook Lee, Yoon-Cheol Ha, Chan-Hee Chae, George R. Beck, Jr and Myung-Haing Cho