Phosphate additives in food cause artery damage and premature aging

15 February 2012

There is increasing evidence that an elevated level of phosphate in the blood not only promotes calcification of blood vessels and bodily organs but also upsets a complex hormonal system involved in regulation of phosphate in the body.

Prof Dr Eberhard Ritz, of the Heidelberg Kidney Centre, and co-authors review the research on phosphate additives and elevated phosphate levels in blood (hyperphosphatemia) in an article in Deutsches Ärzteblatt International [1].

It has long been known that patients with renal disease are at risk of higher cardiovascular related mortality and overall mortality due to elevated phosphate levels. Large-scale epidemiological studies have now shown that phosphate additives may also harm people with normal kidney function. One study has even shown an association with hardening of blood vessels in young healthy men.

Phosphate added to animal fodder is known to accelerate age-related organ complications in animals, such as muscle and skin atrophy, the progression of chronic renal failure, and cardiovascular calcifications. It is now thought that phosphate added to human food has similar effects.

It has only recently been discovered that the body uses a complex system to control phosphate levels in the blood and excretion by the kidneys — in fact there are two hormone systems to prevent phosphate accumulation. Studies with mice where this system has been damaged resulted in premature aging, with vascular calcification, osteoporosis, skin atrophy, pulmonary emphysema, infertility, and early death.

Phosphate induces calcification of the blood vessels both by precipitation of calcium phosphate and also by reprogramming smooth-muscle cells in the blood vessels to become osteoblast-like cells, ie bone-forming cells. In addition, the cells that line the interior of blood vessels — endothelial cells — are impaired by increased phosphate intake.

The authors say that these phosphate-induced changes to the vascular system "may be the link connecting elevated serum phosphate concentrations to premature aging and death".

Phosphate occurs naturally in many foods, including meat, potatoes, bread and starchy products, but this is organically bound and only 40-60% is absorbed on the gut. Phosphate added to food for manufacturing purposes, however, is almost completely absorbed.

In the European Union various types of phosphate are allowed as additives in food production as preservatives, acidifying agents, acidity buffers, emulsifying agents, stabilisers or taste intensifiers and are given an 'E' number: sodium phosphate (E339), potassium phosphate (E340), calcium phosphate (E341), and salts of orthophosphoric acid diphosphate (E450), triphosphate (E451), and polyphosphate (E452). Current legislation, however, does not require phosphate content to be displayed on the package.

 Foods with large amounts of added phosphates include cola and other soft drinks, processed meat, ham, sausages, processed cheese, canned fish and baked goods. In processed meat and poultry products phosphate levels were found to be double that of the natural product due to additives — as a preservative and to bind water to protein (by loosening the protein structure). Phosphates are also used in sterilized, ultra heat-treated, thickened, and powdered milk, and other food powders such as coffee powder to prevent particles sticking together.

As a consequence, the phosphate content of industrially processed food is much higher than that of natural food. Fast food and ready-to-eat processed foods are the main cause of the increasing intake of phosphorus in the diet. The estimated daily intake of phosphate from food additives has more than doubled since the 1990's from about 500mg per day to over 1000mg per day.

Call for public education

The authors call for public education and food labelling "to inform physicians and the public thoroughly about the potential risks to cardiovascular and renal function arising from dietary phosphate consumption". They say that the increasing elderly population and prevalence of chronic diseases such as diabetes, hypertension and coronary heart disease, that damage the kidneys and accelerate the age-related decline of renal function, have further implications for health policy.

They call for both a comprehensive labelling of food to indicate phosphate content to the consumer and a quantitative restriction of phosphate additives.

Reference

1. Ritz E, Hahn K, Ketteler M, Kuhlmann MK, Mann J: Phosphate additives in food — a health risk. Dtsch Arztebl Int 2012; 109(4): 49–55. DOI: 10.3238/arztebl.2012.0049

Direct link: www.aerzteblatt.de/pdf.asp?id=119592

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