There have also been no studies on the levels of phosphates and potassium contained in fresh meat and poultry products that have been 'enhanced.'

Richard Sherman and Ojas Mehta, from the University of Medicine and Dentistry of New Jersey, examined potassium and phosphate content in a variety of 'enhanced' and additive-free meat and poultry products available in local supermarkets.

They found that products that were labelled as 'enhanced' had an average phosphate concentration that was 28 percent higher than additive-free products, with some products almost 100 percent higher.

'The burden imposed on those seeking to limit dietary phosphorus and potassium could be ameliorated by more complete food labelling by manufacturers,' the authors wrote.

The study will appear in the Clinical Journal of the American Society of Nephrology (CJASN).