Pilot Randomized Controlled Trial of a Standard Versus a Modified Low-Phosphorus Diet in Hemodialysis Patients

Abstract

Introduction:The standard low-phosphorus diet restricts pulses, nuts, and whole grains and other high phosphorus foods to control hyperphosphatemia. We conducted a randomized controlled trial to evaluate the effectiveness, safety, and tolerability of the modified diet, which introduced some pulses and nuts, increased the use of whole grains, increased focus on the avoidance of phosphate additives, and introduced the prescription of low-biological-value protein such as bread.Methods: We conducted a multicenter, pragmatic, parallel-arm, open-label, randomized controlled trial of modified versus standard diet in 74 adults on hemodialysis with hyperphosphatemia over 1 month. Biochemistry was assessed using monthly laboratory tests. Dietary intake was assessed using a 2-day record of weighed intake of food, and tolerability was assessed using a patient questionnaire.Results: There was no significant difference in the change in serum phosphate between the standard and modified diets. Although total dietary phosphorus intake was similar, phytate-bound phosphorus, found in pulses, nuts, and whole grains, was significantly higher in the modified diet (P < 0.001). Dietary fiber intake was also significantly higher (P < 0.003), as was the percentage of patients reporting an increase in bowel movements while following the modified diet (P ¼ 0.008). There was no significant difference in the change in serum potassium or in reported protein intake between the 2 diets. Both diets were similarly well tolerated. Conclusion:The modified low phosphorus diet was well tolerated and was associated with similar phosphate and potassium control but with a wider food choice and greater fiber intake than the standard diet.

The effect of dietary phosphorus load and food matrix on postprandial serum phosphate in hemodialysis patients: a pilot study

“…This feeding study supported the postprandial safety and tolerability of the modified versus the standard diet, and allowed for further evaluation of the modified diet a randomised controlled trial of 74 patients over one month which concluded that the diet was well tolerated and was associated with similar phosphate and potassium control but with a wider food choice and greater fiber intake than the standard diet 64 . This feeding study should be repeated, with larger numbers in the afternoon or evening.…”

Effect of a plant protein‐rich diet on postprandial phosphate metabolism in healthy adult men: a randomised controlled trial

“…A study by Shah et al reported decreases in urinary phosphorus and calcium excretion as well as blood calcium levels in type 2 diabetes patients who consumed a high‐fibre diet (50 g/day) for 6 weeks 21 . Byrne et al also reported that a 1‐month study of two diets to control hyperphosphataemia in adults on haemodialysis showed no significant difference in serum phosphate levels, despite significantly higher dietary fibre intake in subjects in one of the groups (both groups had equivalent dietary phosphorus intake) 22 . Because most of these studies were relatively long term, it is difficult to make a clear comparison with our study.…”

The “FIFTY SHADOWS” of the RALES Trial: Lessons about the Potential Risk of Dietary Potassium Supplementation in Patients with Chronic Kidney Disease

“…Third, the bioavailability of inorganic K + (as provided in the SSaSS trial) is not necessarily equivalent to that of K + derived from a fruit- or vegetable-rich diet, as we already know from the strikingly different intestinal bioavailability of phosphate from inorganic (i.e., additives) versus plant-derived phosphate sources [ 19 , 58 ]. The anion linked to K + , other nutrients (e.g., magnesium, vitamin K), protein (with lower phosphate bioavailability), higher fiber content (enhancing intestinal motility and short-chain fatty acid production), or alkali (neutralising acidosis and its harmful consequences) in plant-based or adapted “healthy” diets may have contributed to the outcomes of different studies [ 25 , 59 , 60 , 61 ]. These factors may also explain the unclear correlation between dietary and serum K + [ 51 , 61 ].…”

“…These factors may also explain the unclear correlation between dietary and serum K + [ 51 , 61 ]. As was recently reported [ 25 , 61 ], the traditional dietary paradigm limiting the intake of fruits and vegetables to CKD patients because of their high K + content is rapidly evolving due to the potential pleiotropic benefits deriving from a fundamentally vegetarian or Mediterranean-adapted diet [ 59 , 60 ]. These also include improvement in gut dysbiosis and decreased production of harmful uraemic toxins, together with reductions in inflammation and oxidative stress [ 25 ].…”