Phosphate Additives in Food—a Health Risk
10 February 2012Meat and food products with a high phosphate content should be labelled and there should be a greater public education programme about the use of phosphates, according to a new study published in Deutsches Ärzteblatt International, writes TheMeatSite Editor in Chief Chris Harris.
The research by Eberhard Ritz, Kai Hahn, Markus Ketteler, Martin K. Kuhlmann, Johannes Mann found that elevated serum phosphate concentrations have been found to be correlated with mortality in patients with chronic renal failure, while high-normal serum phosphate concentrations have been found to be correlated with cardiovascular morbidity in the general population.
Unlike naturally occurring phosphate in food, which mainly takes the form of phosphate esters, phosphate in food additives is almost completely resorbed in the gastrointestinal tract.
Phosphate occurs naturally in the form of organic esters in many kinds of food, including meat, potatoes, bread, and other farinaceous products; the consumption of such foods cannot be restricted without incurring the risk of lowering protein intake.
Naturally occurring phosphate in food is organically bound, and only 40 per cent to 60 per cent of it is absorbed in the gastrointestinal tract.
On the other hand, an avoidable risk to health that has not attracted sufficient attention to date arises from the increased use of phosphate as a food additive and preservative.
This "free" (not organically bound) phosphate is very effectively absorbed in the gastrointestinal tract. Typical foods with large amounts of added phosphate are processed meat, ham, sausages, canned fish, baked goods, cola drinks, and other soft drinks.
The research team says that this kind of phosphate is thought to cause vascular damage and to induce aging processes.
Because of the potential damage to health from excessive phosphate consumption, the researchers say that a labelling requirement should be introduced for foods with added phosphate.
Although extensive pathobiological and epidemiological data are now available on this subject, data from prospective studies are still lacking.
The research team said that hyperphosphatemia has been identified in the past decade as a strong predictor of mortality in advanced chronic kidney disease (CKD).
For example, a study of patients in stage CKD 5 (with an annual mortality of about 20 per cent) revealed that 12 per cent of all deaths in this group were attributable to an elevated serum phosphate concentration. Recently, a high-normal serum phosphate concentration has also been found to be an independent predictor of cardiovascular events and mortality in the general population.
Therefore, phosphate additives in food are a matter of concern, and their potential impact on health may well have been underappreciated.
The researchers reviewed pertinent literature retrieved by a selective search of the PubMed and EU databases (www.zusatzstoffe-online.de, www.codexalimentarius.de), with the search terms "phosphate additives" and "hyperphosphatemia."
They said that there is no need to lower the content of natural phosphate, i.e. organic esters, in food, because this type of phosphate is incompletely absorbed; restricting its intake might even lead to protein malnutrition. On the other hand, inorganic phosphate in food additives is effectively absorbed and can measurably elevate the serum phosphate concentration in patients with advanced CKD.
Foods with added phosphate tend to be eaten by persons at the lower end of the socioeconomic scale, who consume more processed and "fast" food.
The main pathophysiological effect of phosphate is vascular damage, e.g. endothelial dysfunction and vascular calcification. Aside from the quality of phosphate in the diet (which also requires attention), the quantity of phosphate consumed by patients with advanced renal failure should not exceed 1000 mg per day, according to the guidelines.
Prospective controlled trials are currently unavailable, the research team said.
In view of the high prevalence of CKD and the potential harm caused by phosphate additives to food, the public should be informed that added phosphate is damaging to health and labelling the content of added phosphate in food are appropriate.
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