Effect of boiling on dietary phosphate and nitrogen intake.

OBJECTIVE: Dietary phosphate restriction is one of the means of phosphatemia control in dialysis patients. To limit dietary phosphate intake, appropriate food choices are recommended, but this often creates a conflict with the high-normal protein requirement of dialysis patients. Although food processing by boiling may be a safe tool for eliminating many minerals, this method poses a risk for loss of important nutrients, including proteins. The goal of this study was to assess the effect of boiling on phosphate and protein nitrogen changes in commonly used foods that contain proteins of high biological value. METHODS: We evaluated the true retention values of dry matter, crude protein, and total phosphorus in fresh beef and chicken breast before and after 10, 20, and 30 minutes of boiling; the reported values represent the average of five determinations. RESULTS: Compared with crude raw samples, dry matter retention in cooked beef was reduced up to 92% +/- 6%, crude protein retention was reduced up to 87% +/- 10%, and phosphorous retention was reduced up to 42% +/- 13%; similar data were obtained when boiling the chicken breast, 93% +/- 3%, 81% +/- 4%, and 63% +/- 6%, respectively. CONCLUSIONS: Our results show that consuming boiled foods can significantly reduce dietary phosphate while preserving protein intake, namely reducing the effective phosphate intake per gram of dietary protein. This can represent additional advice to the patient for limiting the dietary phosphorus load at the same protein intake, leading to a better control of phosphate balance together with a lower risk of protein malnutrition.

Phosphate control in chronic uremia: don't forget diet.

Control of the phosphate balance is a major concern for chronic dialysis patients and it depends on dietary intake, intestinal binding and dialytic removal. Phosphorus mass transfer through dialysis and new phosphorus binders have been widely investigated, but negligible attention has been given to dietary phosphorus management, because of the problems of poor compliance and conflict with the recommended high protein intake. The nutritional target in dialysis patients should be a diet supplying adequate protein but limited phosphate intake, without dramatic changes of dietary habits and lifestyle. It is important to educate patients regarding phosphorus content of current foods so that foods providing less phosphorus with the same protein content can be selected, thus preventing dietary phosphate overload. On the basis of a three-day dietary record, dieticians should give the patient personalised advice in order to reduce phosphorus intake while ensuring the desired protein and energy intake. Dietary manipulation may have little impact on the dialysis population but in individual patients dietary counselling can greatly improve phosphate control. Close co-operation between nephrologists and dieticians is needed to motivate patients and ensure compliance, if dietary intervention is to succeed. All patients should be given dietary education and counselling, especially young-adults, because dietary phosphate control is an important component of an integrated therapeutic approach to phosphate retention and hyperphosphatemia in end-stage renal disease.