title: Novel differential measurement of natural and added phosphorus in cooked ham with or without preservatives.
abstract: OBJECTIVE
  Assessment of the quantity and chemical type of phosphorus (P) content in cooked ham products with or without preservatives using a novel biochemical procedure.
  
  
  METHODS
  We examined the quantity and types of P in 40 samples of cooked ham, including 20 without and 20 with P-containing preservatives, which were purchased randomly from a grocery store in Italy. Food samples were analyzed for dry matter, nitrogen, fat, and P content. Novel spectrophotometric methods were used to measure total P and 3 different P subtypes, that is, water-soluble (inorganic) P including added preservatives and natural P derived from phospholipids and phosphoproteins, separately.
  
  
  RESULTS
  Compared with hams without preservatives, hams with P-containing preservatives had significantly lower dry matter and protein and fat contents. There was 66% more inorganic P (IP) in ham with preservatives than in samples without preservatives (169 ± 36 vs. 102 ± 16 mg/100 g, P < .001, respectively). There were no significant differences in P contents derived from proteins or lipids. The P-to-protein ratio was higher in ham samples with preservatives than in those without preservatives (16.1 ± 4.0 and 9.8 ± 0.8 mg/g, P < .001). The sum of measured IP and P from phospholipids and phosphoproteins was 91% ± 4% of measured total P (207.1 ± 50.7 vs. 227.2 ± 54.4 mg/100 g), indicating a small portion of unspecified P and/or under measurement.
  
  
  CONCLUSIONS
  Novel differential dietary P measurement detects added P-containing preservatives. Cooked ham with preservatives has 66% more measurable IP and 64% higher P-to-protein ratio than ham without preservatives. The contribution of food added with P-containing preservatives to global dietary P burden can negatively influence chronic kidney disease outcome and counteract the efficacy of P-binder medications: this is an important topic that warrants additional investigations.
authors.affiliation: Department of Internal Medicine, Section of Nephrology, University of Pisa, Pisa, Italy. acupisti@med.unipi.it
authors.forename: Adamasco
authors.initials: A
authors.lastname: Cupisti
authors.forename: Omar
authors.initials: O
authors.lastname: Benini
authors.forename: Valerio
authors.initials: V
authors.lastname: Ferretti
authors.forename: Daniela
authors.initials: D
authors.lastname: Gianfaldoni
authors.forename: Kamyar
authors.initials: K
authors.lastname: Kalantar-Zadeh
mesh_terms: D000818:Animals; D003890:Desiccation; D004032:Diet; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation; D005520:Food Preservatives / Q000032:analysis; D007558:Italy; D008461:Meat Products / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D016226:Phosphorus, Dietary / Q000032:analysis*; D013552:Swine
chemical_list: D005520:Food Preservatives; D016226:Phosphorus, Dietary; D010758:Phosphorus; D009584:Nitrogen