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Dietary Intervention in Phosphatemia Control–Nutritional Traffic Light Labeling

      The control of phosphatemia has been increasingly recognized as an important strategy for dialysis patients' because hyperphosphatemia is a risk factor for cardiovascular diseases, progression of kidney disease, and mortality in chronic kidney disease (CKD) as a whole.
      • Waheed A.A.
      • Pedraza F.
      • Lenz O.
      • Isakova T.
      Phosphate control in end-stage renal disease: barriers and opportunities.
      The prevention and correction of hyperphosphatemia are important components of CKD, achieved by dietary phosphate restriction, phosphate binders administration, and adequate dialysis.
      • Waheed A.A.
      • Pedraza F.
      • Lenz O.
      • Isakova T.
      Phosphate control in end-stage renal disease: barriers and opportunities.
      In this context, we emphasize the importance of knowledge about the phosphate content in food and we developed the “phosphate traffic light”, as a new tool for nutrition education and suggestion to improve nutrition labels.
      Dietary phosphate comes in an organic form (phospholipids and phosphoproteins), such as meat and dairy products, and in an inorganic form as food additives that are increasingly added to processed foods and beverages.
      • Chiu Y.-W.
      • Teitelbaum I.
      • Misra M.
      • de Leon E.M.
      • Adzize T.
      • Mehrotra R.
      Pill burden, adherence, hyperphosphatemia, and quality of life in maintenance dialysis patients.
      However, estimates of dietary phosphate intake rarely considers the amount of phosphorus in mineral supplements, water, or food additives.
      • Nolan C.R.
      • Qunibi W.Y.
      Treatment of hyperphosphatemia in patients with chronic kidney disease on maintenance hemodialysis.
      This is extremely important because phosphate supplied in additives is more easily absorbed in the gastrointestinal tract.
      • Uribarri J.
      Phosphorus homeostasis in normal health and in chronic kidney disease patients with special emphasis on dietary phosphorus intake.
      Protein from animal origin, such as meat, fish, and dairy products contains phosphate mainly in an organic form which is easily hydrolyzed and absorbed by the human digestive system.
      • Waheed A.A.
      • Pedraza F.
      • Lenz O.
      • Isakova T.
      Phosphate control in end-stage renal disease: barriers and opportunities.
      High-protein plant based foods, such as legumes, nuts, cereals and seeds, contain phosphate mainly in phytate, or the phytic acid form. This type is not dissolved in the human intestine due to the lack of phytase enzyme, responsible for phosphate liberation.
      • Waheed A.A.
      • Pedraza F.
      • Lenz O.
      • Isakova T.
      Phosphate control in end-stage renal disease: barriers and opportunities.
      In general, intestinal absorption is lower in foods of vegetable origin rather than in animal origin.
      • Fouque D.
      • Horne R.
      • Cozzolino M.
      • Kalantar-Zadeh K.
      Balancing nutrition and serum phosphorus in maintenance dialysis.
      In food, extra quantities of inorganic phosphorus may be added as food additives, of which polyphosphates are their main components. The content of phosphate in processed foods is much higher than in raw foods.
      • Watanabe M.T.
      • Araujo R.M.
      • Vogt B.P.
      • Barretti P.
      • Caramori J.C.T.
      Most consumed processed foods by patients on hemodialysis: alert for phosphate-containing additives and the phosphate-to-protein ratio.
      Ordinary sources of inorganic phosphate include soft drinks, processed meat, frozen food, cereals, snacks, processed cheese, and instant products.
      However, it is important to emphasize that nutritional labels do not indicate phosphate quantities in foods.
      • Uribarri J.
      Phosphorus additives in food and their effect in dialysis patients.
      There are not laws or regulations in place requiring manufacturers to indicate such amounts in food packages, which makes it very difficult to estimate the amount of phosphate in foods.
      • Fouque D.
      • Horne R.
      • Cozzolino M.
      • Kalantar-Zadeh K.
      Balancing nutrition and serum phosphorus in maintenance dialysis.
      We consider the nutritional traffic light label a complete and ideal tool for foods containing phosphate. This would quantitively indicate phosphate content and the presence of additives. Thus, red would indicate RISK (excessive amount), yellow would indicate WARNING (moderate amount), and green would indicate FREE (small phosphate amount). The intention is to make the information on labels more understandable, directing people to make education choices for health. It is a long way to go to achieve such measures; it involves consumer defense agencies, medical and nutritional advice, government bodies, and support from the food industry. There is a lack of information about the harmful effects of phosphate excess for consumers, despite the scientific research and propagation of knowledge to medical institutions.
      Despite all the potential problems described previously, studies have shown that nutritional education focused on processed food restriction is very viable and effective on dialysis patients. The efficacy of this approach is strongly supported by a controlled randomized clinical trial, which assessed the impact of dietetic counseling focused on food additive restriction (intervention group) versus conventional nutritional counseling on phosphatemia in a maintenance hemodialysis population. After 3 months, the phosphatemia average significantly decreased in the intervention group, providing evidence on the effects of additives on hyperphosphatemia.
      • Sullivan C.
      • Sayre S.S.
      • Leon J.B.
      • et al.
      Effect of food additives on hyperphosphatemia among patients with end-stage renal disease: a randomized controlled trial.
      In this context, Reddy et al.
      • Reddy V.
      • Symes F.
      • Sethi N.
      • et al.
      Dietitian-led education program to improve phosphate control in a single-center hemodialysis population.
      suggest that educational initiatives are effective in improving patients' knowledge about phosphate, and consequently, improve control of hyperphosphatemia. The authors studied 115 patients who had classes about phosphate and noted a significant reduction in phosphatemia in patients' hyperphosphatemic pre-intervention.
      Although the effect of focused dietary counseling is motivating, its efficacy may be harmed by the presence of “hidden” phosphate. Labels of many food products do not contain the entire list of additives,
      • Fouque D.
      • Horne R.
      • Cozzolino M.
      • Kalantar-Zadeh K.
      Balancing nutrition and serum phosphorus in maintenance dialysis.
      making the challenge even greater for patients. Previous studies, through lab analysis, have shown the scope of this problem. Results found that various food items contain higher phosphate content than their labels or a nutritional database suggest.
      • Watanabe M.T.
      • Araujo R.M.
      • Vogt B.P.
      • Barretti P.
      • Caramori J.C.T.
      Most consumed processed foods by patients on hemodialysis: alert for phosphate-containing additives and the phosphate-to-protein ratio.
      • Sullivan C.M.
      • Leon J.B.
      • Sehgal A.R.
      Phosphorus-containing food additives and the accuracy of nutrient databases: implications for renal patients.
      An important action for CKD patients is to learn about processed foods and to check carefully the nutritional food composition. Well-informed people have better chances of making appropriate food choices, resulting in a decrease in the complications associated with hyperphosphatemia. The data presented further emphasizes the importance of knowledge about phosphate content in foods for nutritional counseling of CKD patients. Nutritional education focused on additives may improve hyperphosphatemia control, whether using tools such as the “Phosphate traffic light” or by including nutritional information on food labeling. Individuals with renal disease and the general population should choose healthier products with less added phosphate for consumption and for health benefits.

      References

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        Phosphate control in end-stage renal disease: barriers and opportunities.
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        • Misra M.
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        Pill burden, adherence, hyperphosphatemia, and quality of life in maintenance dialysis patients.
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        Treatment of hyperphosphatemia in patients with chronic kidney disease on maintenance hemodialysis.
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        Phosphorus homeostasis in normal health and in chronic kidney disease patients with special emphasis on dietary phosphorus intake.
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        Balancing nutrition and serum phosphorus in maintenance dialysis.
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