Scientists from Harvard University and Nagasaki University Graduate School of Biomedical Sciences in Japan reported this week that high levels of phosphate may accelerate the signs of ageing. Their findings, obtained using genetically engineered mice, are published in the FASEB Journal.
Using mice engineered to lack a gene that allows accumulation of phosphate in the body, the researchers found that toxic levels of the compound cut lifespan by between 25 and 60 per cent, compared with mice engineered to lack this gene but possess another gene involved in phosphate clearance. When mice similar to those in the second group were fed a high phosphate containing diet, the lifespan was again reduced by about 25 per cent, said the researchers.
The mechanism by which toxic levels of phosphate may accelerate ageing is not clearly elucidated, but the researchers proposed that it was most likely through impairment of the functioning of various organs, such as the kidneys.
Media merry-go round
Phosphates are used in foods for a variety of functions, particularly to increase water retention, improve texture, and enhance flavour in meats, cheeses, beverages and bakery goods. Certain foods, such as meats, dairy products, whole grains, and nuts, naturally contain high levels of phosphorous.
Despite no mention of soft drinks, processed foods or phosphates as food additives in the actual paper, the journal issued a press release with a quote from the its editor-in-chief, Gerald Weissmann, MD linking phosphates and ageing to soft drink consumption.
“Soda is the caffeine delivery vehicle of choice for millions of people worldwide, but comes with phosphorous as a passenger,” stated Dr Weissmann. “This research suggests that our phosphorous balance influences the aging process, so don't tip it.”
Mainstream media outlets have picked up on the release and run articles with headlines like: “Drinking too much pop can speed up the ageing process” (UK’s Daily Mail).
However, the industry was quick to respond to the statements. Richard Laming, media director at the British Soft Drinks Association (BSDA) said: "One should not read too much into the findings of this study. It is a study of mice with a specific genetic deformity, and does not in fact mention soft drinks at all.
"Phosphoric acid is used in some soft drinks as a flavouring, but only 3 per cent of phosphorous in the overall diet comes from soft drinks.
People can continue to enjoy soft drinks in moderation as part of a balanced diet."
Barbara Gallani, Director of Food Safety and science at the Food and Drink Federation (FDF) told FoodNavigator: “Phosphates are approved as additives for use in some food and drink products. Their use is in very small amounts and is controlled by very strict EU legislation.”
Last year, an animal study from Korea linked phosphates to increased risk of lung cancer. Dr Myung-Haing Cho of Seoul National University, whose work was published in the American Journal of Respiratory and Critical Care Medicine, said that phosphates are being added more commonly to processed food products than in the past.
Dr Cho said that in the 1990s, phosphorous-containing additives contributed around 470 mg per day to the average adult diet.
Now, he said, intakes may have risen by as much as 1000mg per day, depending on people’s food choices.
Concerns have also been raised about phosphates intakes for people with advanced kidney disease.
Source: FASEB Journal
Published online ahead of print, doi:10.1096/fj.09-152488
“Dietary and genetic evidence for phosphate toxicity accelerating mammalian aging”
Authors: M. Ohnishi, M.S. Razzaque