Dietary Phosphorus Restriction in Dialysis Patients: Potential Impact of Processed Meat, Poultry, and Fish Products as Protein Sources

Association Between Dietary Intake of Phosphorus and Measures of Obesity in the Jackson Heart Study

BACKGROUND

The relation between phosphorus (P) intake and obesity is equivocal, with hypotheses in both directions.

OBJECTIVES

We investigated the relationship between P intake, assessed from a current database, and calculated bioavailable P intake and obesity among African-American adults.

METHODS

We examined associations between original and bioavailable P (total, added, and natural) and BMI and waist circumference (WC) in a cross-sectional study of 5306 African-American adults (21-84 y) from the Jackson Heart Study. A total of 3300 participants had complete interviews, valid dietary data, and normal kidney function. Diet was assessed by food frequency questionnaire. A novel algorithm was used to estimate P bioavailability. BMI or WC was regressed on each P variable, adjusting for total energy intake and potential confounders.

RESULTS

After adjusting for covariates, original P (total and added) and bioavailable P (total and added) intakes (expressed/100 mg) were associated with BMI (β: 0.11, 0.67, 0.31, and 0.71, respectively; all P < 0.0001). Neither original nor bioavailable natural P was significantly associated (β: -0.03 and 0.09, respectively; both P > 0.05). When added and natural P were included in the same model, added P (original and bioavailable) intakes remained strongly associated with BMI (0.70 and 0.73, respectively; both P < 0.0001). Similar results were seen for WC. Intake of original added P tended to be more strongly associated with BMI, in females (β: 0.72; P < 0.0001) than in males (β: 0.56; P = 0.003) (P-interaction = 0.06).

CONCLUSIONS

We found that greater intake of added, not natural, which may be a proxy for intake of processed foods was associated with higher BMI and WC. These were somewhat stronger when bioavailability was considered and for women than for men. Further investigation is needed to fully understand the mechanisms driving these associations.

[Diagnosis and treatment of osteoporosis in patients with chronic kidney disease : Joint guidelines of the Austrian Society for Bone and Mineral Research (ÖGKM), the Austrian Society of Physical and Rehabilitation Medicine (ÖGPMR) and the Austrian Society of Nephrology (ÖGN)]

DEFINITION AND EPIDEMIOLOGY

Chronic kidney disease (CKD): abnormalities of kidney structure or function, present for over 3 months. Staging of CKD is based on GFR and albuminuria (not graded). Osteoporosis: compromised bone strength (low bone mass, disturbance of microarchitecture) predisposing to fracture. By definition, osteoporosis is diagnosed if the bone mineral density T‑score is ≤ -2.5. Furthermore, osteoporosis is diagnosed if a low-trauma (inadequate trauma) fracture occurs, irrespective of the measured T‑score (not graded). The prevalence of osteoporosis, osteoporotic fractures and CKD is increasing worldwide (not graded). PATHOPHYSIOLOGY, DIAGNOSIS AND TREATMENT OF CHRONIC KIDNEY DISEASE-MINERAL AND BONE DISORDER (CKD-MBD): Definition of CKD-MBD: a systemic disorder of mineral and bone metabolism due to CKD manifested by either one or a combination of the following: abnormalities of calcium, phosphorus, PTH, or vitamin D metabolism; renal osteodystrophy; vascular calcification (not graded). Increased, normal or decreased bone turnover can be found in renal osteodystrophy (not graded). Depending on CKD stage, routine monitoring of calcium, phosphorus, alkaline phosphatase, PTH and 25-OH-vitamin D is recommended (2C). Recommendations for treatment of CKD-MBD: Avoid hypercalcemia (1C). In cases of hyperphosphatemia, lower phosphorus towards normal range (2C). Keep PTH within or slightly above normal range (2D). Vitamin D deficiency should be avoided and treated when diagnosed (1C).

DIAGNOSIS AND RISK STRATIFICATION OF OSTEOPOROSIS IN CKD

Densitometry (using dual X‑ray absorptiometry, DXA): low T‑score correlates with increased fracture risk across all stages of CKD (not graded). A decrease of the T‑score by 1 unit approximately doubles the risk for osteoporotic fracture (not graded). A T-score ≥ -2.5 does not exclude osteoporosis (not graded). Bone mineral density of the lumbar spine measured by DXA can be increased and therefore should not be used for the diagnosis or monitoring of osteoporosis in the presence of aortic calcification, osteophytes or vertebral fracture (not graded). FRAX can be used to aid fracture risk estimation in all stages of CKD (1C). Bone turnover markers can be measured in individual cases to monitor treatment (2D). Bone biopsy may be considered in individual cases, especially in patients with CKD G5 (eGFR < 15 ml/min/1.73 m2) or CKD 5D (dialysis).

SPECIFIC TREATMENT OF OSTEOPOROSIS IN PATIENTS WITH CKD

Hypocalcemia should be treated and serum calcium normalized before initiating osteoporosis therapy (1C). CKD G1-G2 (eGFR ≥ 60 ml/min/1.73 m2): treat osteoporosis as recommended for the general population (1A). CKD G3-G5D (eGFR < 60 ml/min/1.73 m2 to dialysis): treat CKD-MBD first before initiating osteoporosis treatment (2C). CKD G3 (eGFR 30-59 ml/min/1.73 m2) with PTH within normal limits and osteoporotic fracture and/or high fracture risk according to FRAX: treat osteoporosis as recommended for the general population (2B). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) with osteoporotic fracture (secondary prevention): Individualized treatment of osteoporosis is recommended (2C). CKD G4-5 (eGFR < 30 ml/min/1.73 m2) and high fracture risk (e.g. FRAX score > 20% for a major osteoporotic fracture or > 5% for hip fracture) but without prevalent osteoporotic fracture (primary prevention): treatment of osteoporosis may be considered and initiated individually (2D). CKD G4-5D (eGFR < 30 ml/min/1.73 m2 to dialysis): Calcium should be measured 1-2 weeks after initiation of antiresorptive therapy (1C).

PHYSICAL MEDICINE AND REHABILITATION

Resistance training prioritizing major muscle groups thrice weekly (1B). Aerobic exercise training for 40 min four times per week (1B). Coordination and balance exercises thrice weekly (1B). Flexibility exercise 3-7 times per week (1B).

Nutritional Adequacy of Essential Nutrients in Low Protein Animal-Based and Plant-Based Diets in the United States for Chronic Kidney Disease Patients

OBJECTIVES

The nutritional adequacy of both animal-based and plant-based low protein diets (LPDs) and moderate protein diets that are recommended for patients with chronic kidney disease have not been well examined. We therefore analyzed the nutrient content of three representative LPDs and moderate protein diets (lacto-ovo vegetarian, omnivorous, and vegan) containing foods that are likely to be prescribed for nondialyzed chronic kidney disease or chronic dialysis patients in the United States to determine the nutritional adequacy at different levels of protein intake.

METHODS

Theoretical 3-day menus were developed as per current renal dietary guidelines to model each diet at 7 different levels of protein intake (0.5-1.2 g/kilograms body weight/day [g/kg/d]). The diets were analyzed for their content of essential amino acids (EAAs) and other essential nutrients.

RESULTS

At an a priori recognized inadequate dietary protein level of 0.5 g/kg/d, all 3 diets failed to meet the Recommended Dietary Allowances (RDAs) for the following EAAs: histidine, leucine, lysine, and threonine. The omnivorous LPD met both the RDA and Estimated Average Requirement at levels of 0.6 g protein/kg/d or more. The lacto-ovo and vegan diets at 0.6 and 0.8 g protein/kg/d, respectively, were below the RDA for lysine. The amounts of several other vitamins and minerals were not uncommonly reduced below the RDA or Adequate Intake with all 3 LPDs.

CONCLUSION

In comparison to omnivorous LPDs, both vegan and lacto-ovo LPDs are more likely to be deficient in several EAAs and other essential nutrients. To provide sufficient amounts of all EAA, vegan and lacto-ovo LPDs must be carefully planned to include adequate amounts of appropriate dietary sources. Supplements of some other essential nutrients may be necessary with all three LPDs.

Phosphate Dysregulation and Metabolic Syndrome

Phosphorus is one of the most abundant minerals in the human body. It is essential for almost all biochemical activities through ATP formation, intracellular signal transduction, cell membrane formation, bone mineralization, DNA and RNA synthesis, and inflammation modulation through various inflammatory cytokines. Phosphorus levels must be optimally regulated, as any deviations may lead to substantial derangements in glucose homeostasis. Clinical studies have reported that hyperphosphatemia can increase an individual's risk of developing metabolic syndrome. High phosphate burden has been shown to impair glucose metabolism by impairing pancreatic insulin secretion and increasing the risk of cardiometabolic disorders. Phosphate toxicity deserves more attention as metabolic syndrome is being seen more frequently worldwide and should be investigated further to determine the underlying mechanism of how phosphate burden may increase the cardiometabolic risk in the general population.

Bioavailability of phosphorus and kidney function in the Jackson Heart Study

BACKGROUND

High phosphorus (P) exposure may have negative effects on kidney function. Nutrient databases provide total P, but bioavailability varies by source.

OBJECTIVES

We aimed to assess natural, added, and bioavailable P intake, and to relate these to estimated glomerular filtration rate (eGFR) in the Jackson Heart Study (JHS).

METHODS

A total of 3962 African-American participants of the JHS, aged 21-84 y, with urine albumin:creatinine ratio < 30 mg/g, and eGFR ≥ 60 mL · min-1 · 1.73 m-2, and without self-reported kidney disease, were included. Diet was assessed by FFQ. We assigned P in foods as naturally occurring or added, and weighted intake by P bioavailability, based on published literature. Relations between P variables and eGFR were assessed using multivariable regression.

RESULTS

Mean ± SE intakes were 1178 ± 6.7 mg and 1168 ± 5.0 mg for total P, 296 ± 2.8 mg and 291 ± 2.1 mg for bioavailable added P, and 444 ± 2.9 mg and 443 ± 2.2 mg for bioavailable natural P, in participants with eGFR = 60-89 and ≥90 mL · min-1 · 1.73 m-2, respectively. Major sources of total P included fish, milk, beef, eggs, cheese, and poultry; and of added P, fish, beef, processed meat, soft drinks, and poultry. After adjustment for confounders, P intakes, including total (β ± SE: -0.32 ± 0.15; P = 0.03), added (β ± SE: -0.73 ± 0.27; P = 0.01), bioavailable total (β ± SE: -0.62 ± 0.23; P = 0.01), and bioavailable added (β ± SE: -0.77 ± 0.29; P = 0.01), were significantly associated with lower eGFR. However, neither total nor bioavailable P from natural sources were associated with eGFR.

CONCLUSIONS

Added, but not natural, P was negatively associated with kidney function, raising concern about P additives in the food supply. Further studies are needed to improve estimation of dietary P exposure and to clarify the role of added P as a risk factor for kidney disease.

The Mediterranean Diet Protects Renal Function in Older Adults: A Prospective Cohort Study

Background: Chronic kidney disease entails a high disease burden that is progressively increasing due to population aging. However, evidence on the effect of the Mediterranean diet on renal function is limited, in particular among older adults in Mediterranean countries. Methods: Prospective cohort study with 975 community-dwelling adults aged ≥ 60 recruited during 2008–2010 in Spain and followed up to 2015. At baseline, food consumption was obtained using a validated dietary history. Two Mediterranean dietary patterns were used: (i) An a priori-defined pattern, the Mediterranean Diet Adherence Screener (MEDAS score: low adherence: 0–5 points; moderate: 6–8 points; high: 9–14 points); (ii) An a posteriori Mediterranean-like dietary pattern, based on 36 food groups, which was generated using factor analysis. Renal function decline was calculated as an estimated glomerular filtration rate (eGFR) decrease ≥1 mL/min/1.73 m2 per year of follow-up. Results: A total of 104 cases of renal function decline occurred. Compared with participants with a low MEDAS adherence, the multivariable-adjusted odds ratios (95% confident interval) for renal function decline risk were 0.63 (0.38–1.03) for moderate adherence, and 0.52 (0.29–0.95) for high adherence (p-trend: 0.015). Multivariable-adjusted odds ratios (95% confidence interval) for renal function decline risk according to increasing quartiles of the adherence to the a posteriori Mediterranean-like dietary pattern were 1.00, 0.67 (0.38–1.20), 0.65 (0.35–1.19), and 0.47 (0.23–0.96) (p-trend: 0.042). Conclusion: A higher adherence to a Mediterranean diet was associated with a lower risk of renal function decline in older adults, suggesting benefits to health of this dietary pattern in Mediterranean countries.

Phosphate and Cellular Senescence

Cellular senescence is one type of permeant arrest of cell growth and one of increasingly recognized contributor to aging and age-associated disease. High phosphate and low Klotho individually and synergistically lead to age-related degeneration in multiple organs. Substantial evidence supports the causality of high phosphate in cellular senescence, and potential contribution to human aging, cancer, cardiovascular, kidney, neurodegenerative, and musculoskeletal diseases. Phosphate can induce cellular senescence both by direct phosphotoxicity, and indirectly through downregulation of Klotho and upregulation of plasminogen activator inhibitor-1. Restriction of dietary phosphate intake and blockage of intestinal absorption of phosphate help suppress cellular senescence. Supplementation of Klotho protein, cellular senescence inhibitor, and removal of senescent cells with senolytic agents are potential novel strategies to attenuate phosphate-induced cellular senescence, retard aging, and ameliorate age-associated, and phosphate-induced disorders.

The Effect of Dietary Phosphorus Restriction on Urine Protein Excretion in Patients With Proteinuria: A Randomized Controlled Trial

OBJECTIVES

The present study was designed to determine the effect of dietary phosphorus restriction, independent of protein intake, on the urinary protein excretion in patients with proteinuria.

METHODS

Seventy-one patients with proteinuria were enrolled in a parallel randomized controlled trial study. The patients were randomly allocated to receive either a recommended phosphorus-restricted diet (n = 36) or a recommended control diet (n = 35), for 8 weeks. A diet was designed and recommended to participants in a way that both trial groups would receive the same amount of energy and protein and the only significant difference between them was the amount of phosphorus intake. The study outcomes included the changes in spot urine protein-to-creatinine ratio, the changes in serum and urine levels of phosphorus, as well as the changes in estimated glomerular filtration rate (eGFR).

RESULTS

The mean ± standard deviation of age, body mass index, and eGFR of the participants were 59 ± 14 years, 29 ± 5.5 kg/m², and 56.1 ± 21.7 mL/min/1.73 m², respectively. The amount of phosphorus intake decreased significantly in the phosphorus-restricted group compared to the control one (-709 vs. -369 mg/day; P < .001). This decrease is accompanied by a significant reduction in urine protein-to-creatinine ratio in the phosphorus-restricted group; however, this change did not reach a significant level when compared to the control one (the mean change: -75.78 vs. -55.25 mg/g; P = .539). Limiting the phosphorus intake did not change its serum and urine values as well as eGFR at the end of the trial.

CONCLUSIONS

Although adherence to a phosphorus-restricted diet by patients with proteinuria led to a significant decrease in urinary protein excretion, this change was not significantly different from that of the control diet. Further studies with larger sample sizes and different designs will reveal more evidence for a link between phosphorus intake and proteinuria.

Hyperphosphatemia Drives Procoagulant Microvesicle Generation in the Rat Partial Nephrectomy Model of CKD

Hyperphosphatemia has been proposed as a cardiovascular risk factor, contributing to long-term vascular calcification in hyperphosphatemic Chronic Kidney Disease (CKD) patients. However, more recent studies have also demonstrated acute effects of inorganic phosphate (Pi) on endothelial cells in vitro, especially generation of pro-coagulant endothelial microvesicles (MV). Hitherto, such direct effects of hyperphosphatemia have not been reported in vivo. Thirty-six male Sprague-Dawley rats were randomly allocated to three experimental groups: (1) CKD induced by partial nephrectomy receiving high (1.2%) dietary phosphorus; (2) CKD receiving low (0.2%) dietary phosphorus; and (3) sham-operated controls receiving 1.2% phosphorus. After 14 days the animals were sacrificed and plasma MVs counted by nanoparticle tracking analysis. MVs isolated by centrifugation were assayed for pro-coagulant activity by calibrated automated thrombography, and relative content of endothelium-derived MVs was assessed by anti-CD144 immunoblotting. When compared with sham controls, high phosphorus CKD rats were shown to be hyperphosphatemic (4.11 ± 0.23 versus 2.41 ± 0.22 mM Pi, p < 0.0001) with elevated total plasma MVs (2.24 ± 0.37 versus 1.31 ± 0.24 × 10⁸ per ml, p < 0.01), showing increased CD144 expression (145 ± 25% of control value, p < 0.0001), and enhanced procoagulant activity (18.06 ± 1.75 versus 4.99 ± 1.77 nM peak thrombin, p < 0.0001). These effects were abolished in the low phosphorus CKD group. In this rat model, hyperphosphatemia (or a Pi-dependent hormonal response derived from it) is sufficient to induce a marked increase in circulating pro-coagulant MVs, demonstrating an important link between hyperphosphatemia and thrombotic risk in CKD.

Risk Assessment of the Dietary Phosphate Exposure in Taiwan Population Using a Total Diet Study

Phosphorus and calcium are essential nutrients for the human body. However, excessive intake of phosphates and a low calcium:phosphorus ratio can lead to disorders in calcium-phosphorus metabolism, kidney disease, or osteoporosis. In this study, a total diet study (TDS) was used. The total phosphorus concentrations of foods were combined with the average dietary consumption to calculate the estimated daily intake, which was compared with the maximum tolerable daily intake (MTDI) to assess the resulting health risk of total phosphorus exposure. The calcium concentration in food and total calcium intake were also analyzed and estimated to calculate the calcium:phosphorus ratio. In conclusion, the phosphate exposure risks for the Taiwanese population are acceptable. However, the calcium:phosphorus ratio in the Taiwanese population (0.51–0.63) is lower than the reference calcium:phosphorus ratio (1.25).

Low-Cost Investment with High Quality Performance. Bleaching Earths for Phosphorus Reduction in the Low-Temperature Bleaching Process of Rapeseed Oil

Rapeseed oils are a valuable component of the diet. Mostly, there are refined oils deprived of valuable nutrients in the market, hence in recent times cold-pressed and unrefined oils have been available and popular among consumers. However, the low yield of this oil makes this product expensive. The aim of the study was to analyse the effectiveness of phosphorus reduction in crude oils, cold- and hot-pressed in the low-temperature bleaching process. Eight market-available bleaching earths was compared. The effectiveness of 90% was found with 2% (m/m) of Kerolite with hydrated magnesium silicate. An increase in the share of earths to 4% (m/m) resulted in the effectiveness of phosphorus reduction >90% in seven out of eight analysed cases. Bentonite activated with acid with the lowest MgO content was characterised by low efficiency <64%. The research shows that the effectiveness of phosphorus reduction was significantly affected by the composition of earths applied in the bleaching process at ambient temperature. The results of research confirm the high effectiveness of the process as it is not necessary to heat up the oil before the bleaching process. This method is recommended for existing and new industrial plant for two-stage rapeseed oil pressing.

The role of phosphate-containing medications and low dietary phosphorus-protein ratio in reducing intestinal phosphorus load in patients with chronic kidney disease

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication in patients experiencing end-stage renal disease (ESRD). It includes abnormalities in bone and mineral metabolism and vascular calcification. Hyperphosphatemia is a major risk factor leading to morbidity and mortality in patients with chronic kidney disease. Increased mortality has been observed in patients with ESRD, with serum phosphorus levels of >5.5 mg/dL. Therefore, control of hyperphosphatemia is a major therapeutic goal in the prevention and treatment of CKD-MBD. The treatment of hyperphosphatemia includes decreasing intestinal phosphorus load and increasing renal phosphorus removal. Decreasing the intestinal load of phosphorus plays a major role in the prevention and treatment of CKD-MBD. Among the dietary sources of phosphorus, some of the commonly prescribed medications have also been reported to contain phosphorus. However, drugs are often ignored even though they act as a potential source of phosphorus. Similarly, although proteins are the major source of dietary phosphorus, reducing protein intake can increase mortality in patients with CKD. Recently, the importance of phosphorus/protein ratio in food have been reported to be a sensitive marker for controlling dietary intake of phosphorus. This review summarizes the progress in the research on phosphate content in drugs as an excipient and the various aspects of dietary management of hyperphosphatemia in patients with CKD, with special emphasis on dietary restriction of phosphorus with low dietary phosphate/protein ratio.

Preparation, characterization and physicochemical properties of novel low-phosphorus egg yolk protein

BACKGROUND

In order to supply adequate dietary protein for chronic kidney disease (CKD) patients while simultaneously controlling phosphorus intake, a novel method was developed for the preparation of low-phosphorus egg yolk protein (LPYP) using alkaline protease auxiliary dephosphorization. In addition, the physicochemical properties of LPYP were studied.

RESULTS

In comparison with raw egg yolk protein (RYP) and defatted egg yolk protein (DFYP), LPYP was found to exhibit differences in amino acid (AA) composition, protein secondary structure, surface hydrophobicity, solubility and emulsion stability. It was observed that dephosphorization improved the AA composition, soluble protein content and dissolution stability of egg yolk protein. In addition, phosphate groups were found to impose a critical influence on the emulsion stability and particle size distribution. The final phosphorus to protein mass ratio (P/Pro) of LPYP was 5.64, which met the requirements of a protein diet for CKD patients. The FAO/WHO mode closeness and stability coefficient were 0.958 and 98.62% respectively.

CONCLUSION

LPYP can be effectively obtained by alkaline protease hydrolysis and subsequent alkali dephosphorization. The prepared LPYP can be considered to be a type of safe and suitable protein resource for CKD patients. © 2018 Society of Chemical Industry.

Dietary Phosphate and the Forgotten Kidney Patient: A Critical Need for FDA Regulatory Action

Careful dietary management that reduces high phosphate intake is recommended to slow the progression of chronic kidney disease (CKD) and prevent complications of CKD and may help reduce chronic disease risks such as incident CKD associated with high phosphate intake in the healthy general population. For patients treated with maintenance dialysis, control of serum phosphorus levels is considered a marker of good care and requires a coordinated plan that limits dietary phosphate intake, uses oral phosphate binders, and provides an adequate dialysis prescription. Even with traditional thrice-weekly hemodialysis or peritoneal dialysis, use of phosphate binders, and a concerted effort to limit dietary phosphate intake, adequately controlled serum phosphorus levels are not possible in all dialysis patients. Efforts to limit phosphate intake are thwarted by the underestimated and unquantified phosphate content of processed foods and some medications due to the hidden presence of phosphate additives or excipients added during processing or drug formulation. Effectively limiting phosphate intake could potentially be achieved through simple US Food and Drug Administration regulatory actions. Mandatory labeling of phosphate content on all packaged foods and drugs would enable identification of healthy low-phosphate foods and medications and permit critically important control of total phosphate intake. Simple changes in regulatory policy and labeling are warranted and would enable better management of dietary intake of phosphate at all stages of kidney disease, as well as potentially reduced health risks in the general population.

The impact of a nutritional intervention based on egg white for phosphorus control in hemodialyis patients

BACKGROUND AND AIMS

Here we describe a dietary intervention for hyperphosphatemia in dialysis patients based on the partial replacement of meat and fish, which are one of the main sources of alimentary phosphorous, with egg white, a virtually phosphorous-free protein source. This intervention aims to reduce phosphorous intake without causing protein wasting.

PATIENTS AND METHODS

As many as 23 hyperphosphatemic patients (15 male and 8 female, mean age 53.0 ± 10.0 years) on chronic standard 4 h, three times weekly, bicarbonate hemodialysis were enrolled in this open-label, randomized controlled trial. Patients in the intervention group were instructed to replace fish or meat with egg white in three meals a week for three months whereas diet was unchanged in the control group.

RESULTS

Serum phosphate concentrations were significantly lower in the intervention group than in controls after three (4.9 ± 1.0 vs 6.6 ± 0.8; p < 0.001) but not after one month of treatment. Phosphate concentrations decreased more from baseline in the intervention than in the control group both after one (-1,2 ± 1,1 vs 0,5 ± 1,1; p = 0.004) and after three (-1,7 ± 1,1 vs -0,6 ± 1,1; p < 0.001) months of follow-up. No change either in body weight or in body composition assessed with bioelectrical impedance analysis or in serum albumin concentration was observed in either group.

CONCLUSION

The partial replacement of meat and fish with egg white induces a significant decrease in serum phosphate without causing protein malnutrition and could represent a useful instrument to control serum phosphate levels in hemodialysis patients. CLINICALTRIALS.

GOV IDENTIFIER

NCT03236701.

Complementary Biomarker Assessment of Components Absorbed from Diet and Creatinine Excretion Rate Reflecting Muscle Mass in Dialysis Patients

To prevent protein energy malnutrition (PEM) and accumulation of waste products, dialysis patients require diet adjustments. Dietary intake assessed by self-reported intakes often provides biased information and standard 24-h urinary excretion is inapplicable in dialysis patients. We aimed to assess dietary intake via a complementary, less biased biomarker method, and to compare this to dietary diaries. Additionally, we investigated the prospective association of creatinine excretion rate (CER) reflecting muscle mass with mortality. Complete intradialytic dialysate and interdialytic urinary collections were used to calculate 24-h excretion of protein, sodium, potassium, phosphate and creatinine in 42 chronic dialysis patients and compared with protein, sodium, potassium, and phosphate intake assessed by 5-day dietary diaries. Cox regression analyses were employed to investigate associations of CER with mortality. Mean age was 64 ± 13 years and 52% were male. Complementary biomarker assessed (CBA) and dietary assessed (DA) protein intake were significantly correlated (r = 0.610; p < 0.001), but there was a constant bias, as dietary diaries overestimated protein intake in most patients. Correlations were found between CBA and DA sodium intake (r = 0.297; p = 0.056), potassium intake (r = 0.312; p = 0.047) and phosphate uptake/intake (r = 0.409; p = 0.008). However, Bland-Altman analysis showed significant proportional bias. During a median follow-up of 26.6 (25.3–31.5) months, nine dialysis patients (23%) died. CER was independently and inversely associated with survival (HR: 0.59 (0.42–0.84); p = 0.003). Excretion measurements may be a more reliable assessment of dietary intake in dialysis patients, as this method is relatively free from biases known to exist for self-reported intakes. CER seems to be a promising tool for monitoring PEM.

Dietary Phosphorus to Protein Ratio for the Mexican Population with Chronic Kidney Disease

OBJECTIVE

Hyperphosphatemia is a major contributor to poor outcomes among cases of chronic kidney disease. Considering that foods with high protein content are major sources of phosphorus, a more suitable dietary phosphorus measure is the phosphorus to protein ratio. However, Mexican phosphorus to protein ratio tables do not exist. This article aims to estimate the phosphorus to protein ratio in foods commonly used by the Mexican population and to establish its usefulness in the selection of foods for patients with chronic kidney disease.

METHODS

Six tables with the phosphorus to protein ratio were developed from different data sources concerning Mexican animal food composition.

RESULTS

Egg whites have the best phosphorus to protein ratio. Partially skimmed milk has the lowest ratio among dairy products. Dairy products have high phosphorus to protein ratio variability. Red meat products have a ratio with an average of 9 mg/g. The phosphorus to protein ratio varies considerably for seafood (1.2-38.3 mg/g).

CONCLUSIONS

The phosphorus to protein ratio could be a good strategy to choose each food during chronic kidney disease dietary treatment for the Mexican population.

Production of Low-Potassium Content Melon Through Hydroponic Nutrient Management Using Perlite Substrate

Chronic kidney disease patients are restricted to foods with high potassium content but our daily diets including melon are rich in potassium. Therefore, we investigated the production of low-potassium melon through hydroponic nutrient management in soilless culture using perlite substrate during autumn season of 2012, 2014 and spring season of 2016. In the first study, melon plants were supplied with 50% standard 'Enshi' nutrient solution until first 2 weeks of culture. In 3rd and 4th week, amount of applied potassium was 50, 75, 100, and 125% of required potassium nitrate for each plant per week (based on our previous study). It was found that, melon plants grown with 50% of its required potassium nitrate produced fruits with about 53% low-potassium compared to control. In the following study, four cultivars viz. Panna, Miyabi shunjuukei, Miyabi akifuyu412, and Miyabi soushun banshun309 were evaluated for their relative suitability of low-potassium melon production. Results showed insignificant difference in fruit potassium content among the cultivars used. Source of potassium fertilizer as potassium nitrate and potassium sulfate and their restriction (from 1 or 2 weeks after anthesis) were also studied. There were no influences on fruit potassium content and yield due to sources of potassium fertilizer and restriction timings. In our previous studies, it was evident that potassium can be translocated from leaves to fruits at maturity when it was supplied nutrient without potassium. Thus, we also studied total number of leaves per plant (23, 24, 25, 26, and 27 leaves per plant). It was evident that fruit potassium, yield, and quality were not influenced significantly due to differences in number of leaves per plant. These studies showed that restriction of potassium nitrate in the culture solution from anthesis to harvest could produce melon fruits with low-potassium (>20%) content compared to potassium content of greenhouse grown melon (340 mg/100 g FW). Quality testing and clinical validation of low-potassium melon also showed positive responses compared to greenhouse grown melon.

Dietary phosphate toxicity: an emerging global health concern

Phosphate is a common ingredient in many healthy foods but, it is also present in foods containing additives and preservatives. When found in foods, phosphate is absorbed in the intestines and filtered from the blood by the kidneys. Generally, any excess is excreted in the urine. In renal pathologies, however, such as chronic kidney disease, a reduced renal ability to excrete phosphate can result in excess accumulation in the body. This accumulation can be a catalyst for widespread damage to the cellular components, bones, and cardiovascular structures. This in turn can reduce mortality. Because of an incomplete understanding of the mechanism for phosphate homeostasis, and the multiple organ systems that can modulate it, treatment strategies designed to minimize phosphate burden are limited. The Recommended Dietary Allowance (RDA) for phosphorous is around 700 mg/day for adults, but the majority of healthy adult individuals consume far more phosphate (almost double) than the RDA. Studies suggest that low-income populations are particularly at risk for dietary phosphate overload because of the higher amounts of phosphate found in inexpensive, processed foods. Education in nutrition, as well as access to inexpensive healthy food options may reduce risks for excess consumption as well as a wide-range of disorders, ranging from cardiovascular diseases to kidney diseases to tumor formation. Pre-clinical and clinical studies suggest that dietary phosphate overload has toxic and prolonged adverse health effects. Improved regulations for reporting of phosphate concentrations on food labels are necessary so that people can make more informed choices about their diets and phosphate consumption. This is especially the case given the lack of treatments available to mitigate the short and long-term effects of dietary phosphate overload-related toxicity. Phosphate toxicity is quickly becoming a global health concern. Without measures in place to reduce dietary phosphate intake, the conditions associated with phosphate toxicity will likely to cause untold damage to the wellbeing of individuals around the world.

Twenty-Four-Hour Urine Phosphorus as a Biomarker of Dietary Phosphorus Intake and Absorption in CKD: A Secondary Analysis from a Controlled Diet Balance Study

BACKGROUND AND OBJECTIVES

Twenty-four-hour urine phosphorus is commonly used as a surrogate measure for phosphorus intake and absorption in research studies, but its reliability and accuracy are unproven in health or CKD. This secondary analysis sought to determine the reliability and accuracy of 24-hour urine phosphorus as a biomarker of phosphorus intake and absorption in moderate CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Eight patients with stage 3-4 CKD participated in 2-week balance studies with tightly controlled phosphorus and calcium intakes. Thirteen 24-hour urine collections per patient were analyzed for variability and reliability of 24-hour urine phosphorus and phosphorus-to-creatinine ratio. The accuracy of 24-hour urine phosphorus to predict phosphorus intake was determined using a published equation. The relationships of 24-hour urine phosphorus with phosphorus intake, net absorption, and retention were determined.

RESULTS

There was wide day-to-day variation in 24-hour urine phosphorus within and among subjects (coefficient of variation of 30% and 37%, respectively). Two 24-hour urine measures were needed to achieve ≥75% reliability. Estimating dietary phosphorus intake from a single 24-hour urine resulted in underestimation up to 98% in some patients and overestimation up to 79% in others. Twenty-four-hour urine phosphorus negatively correlated with whole-body retention but was not related to net absorption.

CONCLUSIONS

From a sample of eight patients with moderate CKD on a tightly controlled dietary intake, 24-hour urine phosphorus was highly variable and did not relate to dietary phosphorus intake or absorption, rather it inversely related to phosphorus retention.

Influence of pH and phosphate concentration on the phosphate binding capacity of five contemporary binders. An in vitro study

AIM

Hyperphosphataemia is associated with increased mortality and morbidity in end stage renal disease. Despite phosphate binder therapy, a large proportion of patients do not reach the treatment target. In five contemporary binders we explored the influence of pH and phosphate concentration on phosphate binding. This interaction could be of relevance in clinical practice.

METHODS

Phosphate binding was quantified in vitro in 25 mL of purified water containing phosphate concentrations of 10, 15 and 20 mM and baseline pH values of 3.0 or 6.0, with a binder over 6 h. Lanthanum carbonate, calcium acetate/magnesium carbonate, sevelamer carbonate, calcium carbonate and sucroferric oxyhydroxide, 67 mg of each, were used. The experiments were performed in duplicate. The primary outcome was the difference in the amount of bound phosphate for each binder after 6 h in solutions at two different pH values. Secondary outcomes were the influence of phosphate concentration on phosphate binding, next to binding patterns and phosphate binder saturation.

RESULTS AND CONCLUSION

In this specific in vitro setting, lanthanum carbonate, sevelamer carbonate, calcium carbonate and sucroferric oxyhydroxide bound more phosphate in the solution with baseline pH of 3.0. Differences however were small except for lanthanum carbonate. Calcium acetate/magnesium carbonate was most effective in a solution with baseline pH of 6.0. All phosphate binders bound more phosphate in solutions with higher concentrations of phosphate. Sevelamer carbonate, calcium acetate/magnesium carbonate and sucroferric oxyhydroxide bound most phosphate in the first hour and reached maximum binding capacity in less than 6 h.

Dietary phosphorus intake estimated by 4-day dietary records and two 24-hour urine collections and their associated factors in Japanese adults

BACKGROUND/OBJECTIVES

Both self-reported dietary information and urinary excretion have limitations in the assessment of phosphorus intake. We conducted a cross-sectional study to estimate dietary phosphorus intake by dietary records (DR) and 24-h urine collections (UC) and examined associated factors.

SUBJECTS/METHODS

A total of 161 men and 161 women aged 20-69 years completed a 4-day DR and two 24-h UC. Phosphorus intake by UC was estimated using the mean phosphorus absorption rate of 14 papers. Associations between phosphorus intake and urinary excretion and age, body mass index (BMI), physical activity, education, and smoking status were examined using multiple linear regression.

RESULTS

Phosphorus intake estimated by UC was higher than that estimated by DR (mean: 1393 vs. 1176 mg/day, P < 0.0001 in men; 1082 vs. 1021 mg/day, P = 0.008 in women). Values were significantly correlated (r = 0.29, P = 0.0002 in men; r = 0.30, P = 0.0001 in women). Phosphorus intake estimated by DR was positively associated with age in women. Male current smokers consumed less phosphorus than never smokers. Higher urinary phosphorus excretion was associated with higher BMI in both sexes and higher physical activity in women.

CONCLUSIONS

This study showed dietary phosphorus intakes estimated by 4-day DR and by 2-day UC in adults. Although dietary phosphorus intake estimated by DR showed moderate correlation with that by UC, they differed in their association with age, BMI, physical activity, and smoking status.

Sodium-Reduced Meat and Poultry Products Contain a Significant Amount of Potassium from Food Additives

BACKGROUND

Sodium-reduced packaged food products are increasingly available to consumers; however, it is not clear whether they are suitable for inclusion in a potassium-reduced diet. For individuals with impaired renal potassium excretion caused by chronic kidney disease and for those taking certain medications that interfere with the rennin-angiotensin aldosterone axis, the need to limit dietary potassium is important in view of the risk for development of hyperkalemia and fatal cardiac arrhythmias.

OBJECTIVE

The primary objective of this study was to determine the impact of the reduction of sodium in packaged meat and poultry products (MPPs) on the content of potassium and phosphorus from food additives.

DESIGN

This was a cross-sectional study comparing chemically analyzed MPPs (n=38, n=19 original, n=19 sodium-reduced), selected from the top three grocery chains in Canada, based on market share sales. All MPPs with a package label containing a reduced sodium content claim together with their non-sodium-reduced packaged MPP counterparts were selected for analysis. The protein, sodium, phosphorus, and potassium contents of sodium-reduced MPPs and the non-sodium-reduced (original) MPP counterparts were chemically analyzed according to the Association of Analytical Communities official methods 992.15 and 984.27 and compared by using a paired t test. The frequency of phosphorus and potassium additives appearing on the product labels' ingredient lists were compared between groups by using McNemar's test.

RESULTS

Sodium-reduced MPPs (n=19) contained 44% more potassium (mg/100 g) than their non-sodium-reduced counterparts (n=19) (mean difference [95% CI): 184 [90-279]; P=0.001). The potassium content of sodium-reduced MPPs varied widely and ranged from 210 to 1,500 mg/100 g. Potassium-containing additives were found on the ingredient list in 63% of the sodium-reduced products and 26% of the non-sodium-reduced products (P=0.02). Sodium-reduced MPPs contained 38% less sodium (mg/100 g) than their non-sodium-reduced counterparts (mean difference [95% CI]: 486 [334-638]; P<0.001). The amounts of phosphorus and protein, as well as the frequency of phosphorus additives appearing on the product label ingredient list, did not significantly differ between the two groups.

CONCLUSIONS

Potassium additives are frequently added to sodium-reduced MPPs in amounts that significantly contribute to the potassium load for patients with impaired renal handling of potassium caused by chronic kidney disease and certain medications. Patients requiring potassium restriction should be counseled to be cautious regarding the potassium content of sodium-reduced MPPs and encouraged to make food choices accordingly.

Phosphorus Balance in Adolescent Girls and the Effect of Supplemental Dietary Calcium

There are limited data on phosphorus balance and the effect of dietary calcium supplements on phosphorus balance in adolescents. The purpose of this study was to determine phosphorus balance and the effect of increasing dietary calcium intake with a supplement on net phosphorus absorption and balance in healthy adolescent girls. This study utilized stored urine, fecal, and diet samples from a previously conducted study that focused on calcium balance. Eleven healthy girls ages 11 to 14 years participated in a randomized crossover study, which consisted of two 3-week periods of a controlled diet with low (817 ± 19.5 mg/d) or high (1418 ± 11.1 mg/d) calcium, separated by a 1-week washout period. Phosphorus intake was controlled at the same level during both placebo and calcium supplementation (1435 ± 23.5 and 1453 ± 28.0 mg/d, respectively, p = 0.611). Mean phosphorus balance was positive by about 200 mg/d and was unaffected by the calcium supplement (p = 0.826). Urinary phosphorus excretion was lower with the calcium supplement (535 ± 42 versus 649 ± 41 mg/d, p = 0.013), but fecal phosphorus and net phosphorus absorption were not significantly different between placebo and calcium supplement (553 ± 60 versus 678 ± 63 versus mg/d, p = 0.143; 876 ± 62 versus 774 ± 64 mg/d, p = 0.231, respectively). Dietary phosphorus underestimates using a nutrient database compared with the content measured chemically from meal composites by ~40%. These results show that phosphorus balance is positive in girls during adolescent growth and that a calcium dietary supplement to near the current recommended level does not affect phosphorus balance when phosphorus intake is at 1400 mg/d, a typical US intake level.

Contribution of Drinking Water Softeners to Daily Phosphate Intake in Slovenia

The cumulative phosphate intake in a typical daily diet is high and, according to several studies, already exceeds recommended values. The exposure of the general population to phosphorus via drinking water is generally not known. One of the hidden sources of phosphorus in a daily diet is sodium polyphosphate, commonly used as a drinking water softener. In Slovenia, softening of drinking water is carried out exclusively within the internal (household) drinking water supply systems to prevent the accumulation of limescale. The aim of the study was to determine the prevalence of sodium phosphates in the drinking water in Slovenia in different types of buildings, to determine residents' awareness of the presence of chemical softeners in their drinking water, and to provide an exposure assessment on the phosphorus intake from drinking water. In the current study, the presence of phosphates in the samples of drinking water was determined using a spectrophotometric method with ammonium molybdate. In nearly half of the samples, the presence of phosphates as water softeners was confirmed. The measured concentrations varied substantially from 0.2 mg PO4/L to 24.6 mg PO4/L. Nearly 70% of the respondents were not familiar with the exact data on water softening in their buildings. It follows that concentrations of added phosphates should be controlled and the consumers should be informed of the added chemicals in their drinking water. The health risks of using sodium polyphosphate as a drinking water softener have not been sufficiently investigated and assessed. It is highly recommended that proper guidelines and regulations are developed and introduced to protect human health from adverse effects of chemicals in water intended for human consumption.

Effects of l-lysine on thermal gelation properties of chicken breast actomyosin

The effects of l-lysine (l-Lys) on the water holding capacity (WHC) and texture of actomyosin (AM) gel and the possible mechanisms were investigated. l-Lys increased the WHC and hardness of the AM gel. These effects may be related to the even and continuous microstructure of the gel according to the scanning electron microscopy analysis. Furthermore, l-Lys increased the surface hydrophobic residues and the reactive sulfhydryl groups. l-Lys decreased the storage modulus at the first transition temperature but increased it at the second transition temperature and the third transition enthalpy. These results suggested that l-Lys varied the thermal behaviors and the microstructure of the AM gel by increasing the surface hydrophobicity and reactive sulfhydryl groups, ultimately contributing to the increased WHC and hardness. The changes in pH did not fully explain the results from the present study. The results were useful for understanding previous findings and may serve as a reference for the preparation of reduced-sodium and phosphate-free meat products.

Acute tumoral calcinosis due to severe hyperphosphatemia in a maintenance hemodialysis patient

We report the case of a maintenance hemodialysis patient with severe hyperphosphatemia (26.6 mg/dL) who developed acute tumoral calcinosis. The patient started receiving maintenance hemodialysis after being diagnosed with type 2 diabetes mellitus. The patient's phosphate levels suddenly increased. He had not taken the prescribed phosphate binders for the past 5 years. He noticed swelling of the palmar aspects of his right thumb, which was diagnosed as tumoral calcinosis. His serum phosphate level reached 26.6 mg/dL. He started taking medication to lower his serum phosphate levels. The patient had a long history of eating convenience foods. As food additives in convenience foods could be a major source of phosphate, the patient corrected this habit by replacing convenience foods with special foods for dialysis patients. His symptoms improved along with the decrease in his serum phosphate levels. The main reason for the abrupt decrease in phosphate levels could be the correction of his dietary habits. Therefore, phosphate levels in processed foods should be carefully considered in dialysis patients.

The Diet and Haemodialysis Dyad: Three Eras, Four Open Questions and Four Paradoxes. A Narrative Review, Towards a Personalized, Patient-Centered Approach

The history of dialysis and diet can be viewed as a series of battles waged against potential threats to patients' lives. In the early years of dialysis, potassium was identified as "the killer", and the lists patients were given of forbidden foods included most plant-derived nourishment. As soon as dialysis became more efficient and survival increased, hyperphosphatemia, was identified as the enemy, generating an even longer list of banned aliments. Conversely, the "third era" finds us combating protein-energy wasting. This review discusses four questions and four paradoxes, regarding the diet-dialysis dyad: are the "magic numbers" of nutritional requirements (calories: 30-35 kcal/kg; proteins > 1.2 g/kg) still valid? Are the guidelines based on the metabolic needs of patients on "conventional" thrice-weekly bicarbonate dialysis applicable to different dialysis schedules, including daily dialysis or haemodiafiltration? The quantity of phosphate and potassium contained in processed and preserved foods may be significantly different from those in untreated foods: what are we eating? Is malnutrition one condition or a combination of conditions? The paradoxes: obesity is associated with higher survival in dialysis, losing weight is associated with mortality, but high BMI is a contraindication for kidney transplantation; it is difficult to limit phosphate intake when a patient is on a high-protein diet, such as the ones usually prescribed on dialysis; low serum albumin is associated with low dialysis efficiency and reduced survival, but on haemodiafiltration, high efficiency is coupled with albumin losses; banning plant derived food may limit consumption of "vascular healthy" food in a vulnerable population. Tailored approaches and agreed practices are needed so that we can identify attainable goals and pursue them in our fragile haemodialysis populations.

The role of phosphate in kidney disease

The importance of phosphate homeostasis in chronic kidney disease (CKD) has been recognized for decades, but novel insights - which are frequently relevant to everyday clinical practice - continue to emerge. Epidemiological data consistently indicate an association between hyperphosphataemia and poor clinical outcomes. Moreover, compelling evidence suggests direct toxicity of increased phosphate concentrations. Importantly, serum phosphate concentration has a circadian rhythm that must be considered when interpreting patient phosphate levels. Detailed understanding of dietary sources of phosphate, including food additives, can enable phosphate restriction without risking protein malnutrition. Dietary counselling provides an often underestimated opportunity to target the increasing exposure to dietary phosphate of both the general population and patients with CKD. In patients with secondary hyperparathyroidism, bone can be an important source of serum phosphate, and adequate appreciation of this fact should impact treatment. Dietary and pharmotherapeutic interventions are efficacious strategies to lower phosphate intake and serum concentration. However, strong evidence that targeting serum phosphate improves patient outcomes is currently lacking. Future studies are, therefore, required to investigate the effects of modern dietary and pharmacological interventions on clinically meaningful end points.

Phosphate-Containing Prescription Medications Contribute to the Daily Phosphate Intake in a Third of Hemodialysis Patients

OBJECTIVES

Hyperphosphatemia is associated with all-cause mortality in hemodialysis (HD) patients and is managed by restricting dietary phosphate. Many patients are unable to adhere to the recommended dietary phosphate limit. We sought to quantify the additional phosphate burden from prescription medication in a hemodialysis population.

DESIGN

Cross-sectional study.

SUBJECTS

Adult patients on hemodialysis at a single center.

SETTING

The Health Canada Drug Product Database was used to identify formulations of medications prescribed in an HD program that contain phosphate salts. The manufacturers of formulations containing a phosphate salt were contacted to request the phosphate content per tablet, and amounts were confirmed in select medications by the malachite green method.

MAIN OUTCOME MEASUREMENTS

Prescription bottles of 101 HD patients were evaluated. Reported phosphate contents were used to determine patients' daily phosphate load from prescribed medications.

RESULTS

A total 1,744 drug formulations of 124 different medications were reviewed. A total of 185 (11%) contained a phosphate salt. Central nervous system (CNS) and cardiovascular (CVS) medications accounted for 65% and 24% of phosphate-containing medications, respectively. Of HD patients, 30% were taking at least one medication that contained phosphate. The median phosphate burden from prescribed medications was 111 (67-168) mg per day.

CONCLUSIONS

Knowledge about the phosphate content of commonly prescribed drugs within different classes should influence prescribing patterns. Particular consideration of which formulation of CVS and CNS drugs contain phosphate should be applied when prescribing. Phosphate-containing medications can meaningfully contribute to the daily phosphate load in HD patients; however, this burden will differ based on local dispensing patterns.

Diets for patients with chronic kidney disease, should we reconsider?

Here we revisit how dietary factors could affect the treatment of patients with complications of chronic kidney disease (CKD), bringing to the attention of the reader the most recent developments in the field. We will briefly discuss five CKD-induced complications that are substantially improved by dietary manipulation: 1) metabolic acidosis and the progression of CKD; 2) improving the diet to take advantage of the benefits of angiotensin converting enzyme inhibitors (ACEi) on slowing the progression of CKD; 3) the diet and mineral bone disorders in CKD; 4) the safety of nutritional methods utilizing dietary protein restriction; and 5) evidence that new strategies can treat the loss of lean body mass that is commonly present in patients with CKD.

Most consumed processed foods by patients on hemodialysis: Alert for phosphate-containing additives and the phosphate-to-protein ratio

BACKGROUND AND AIMS

Hyperphosphatemia is common in patients with chronic kidney disease (CKD) stages IV and V because of decreased phosphorus excretion. Phosphatemia is closely related to dietary intake. Thus, a better understanding of sources of dietary phosphate consumption, absorption and restriction, particularly inorganic phosphate found in food additives, is key to prevent consequences of this complication. Our aims were to investigate the most commonly consumed processed foods by patients with CKD on hemodialysis, to analyze phosphate and protein content of these foods using chemical analysis and to compare these processed foods with fresh foods.

METHODS

We performed a cross-sectional descriptive analytical study using food frequency questionnaires to rank the most consumed industrialized foods and beverages. Total phosphate content was determined by metavanadate colorimetry, and nitrogen content was determined by the Kjeldahl method. Protein amounts were estimated from nitrogen content. The phosphate-to-protein ratio (mg/g) was then calculated. Processed meat protein and phosphate content were compared with the nutritional composition of fresh foods using the Brazilian Food Composition Table. Phosphate measurement results were compared with data from the Food Composition Table - Support for Nutritional Decisions. An α level of 5% was considered significant.

RESULTS

Food frequency questionnaires were performed on 100 patients (mean age, 59 ± 14 years; 57% male). Phosphate additives were mentioned on 70% of the product labels analyzed. Proteins with phosphate-containing additives provided approximately twice as much phosphate per gram of protein compared with that of fresh foods (p < 0.0001).

CONCLUSIONS

Protein and phosphate content of processed foods are higher than those of fresh foods, as well as phosphate-to-protein ratio. A better understanding of phosphate content in foods, particularly processed foods, may contribute to better control of phosphatemia in patients with CKD.

The Phosphate Content of Prescription Medication: A New Consideration

BACKGROUND

Phosphate restriction is needed in most dialysis patients. The package inserts from some medications indicate that phosphate may be part of the excipient fraction of drugs. It is unclear whether its amount may be clinically significant since the phosphate content is unquantified.

METHODS

We reviewed the package inserts for the branded formulations of the most widely used drugs at a dialysis chain. We measured the phosphate levels in a sample of the branded form of these drugs and some of their generic formulations. We also reviewed the available package inserts of 16 selected generic drug manufacturers for the presence of phosphate in drugs that were phosphate free in their branded formulation.

RESULTS

We identified 12 prescription products that contained phosphate, 9 of which contained clinically significant quantities (>10 mg per daily dose) notably in both branded and generic forms of amlodipine, lisinopril, paroxetine and bisoprolol. Phosphate was rarely present in a generic drug when its corresponding branded formulation was phosphate free.

CONCLUSION

Commonly prescribed drugs may contain clinically important levels of phosphate.

Hyperphosphatemia in Dialysis Patients: Beyond Nonadherence to Diet and Binders

Hyperphosphatemia in dialysis patients is routinely attributed to nonadherence to diet, prescribed phosphate binders, or both. The role of individual patient variability in other determinants of phosphate control is not widely recognized. In a manner that cannot be explained by dialysis parameters or serum phosphate levels, dialytic removal of phosphate may vary by >400mg per treatment. Similarly, enteral phosphate absorption, unexplained by diet or vitamin D intake, may differ by ≥250mg/d among patients. Binder efficacy also varies among patients, with 2-fold differences reported. One or more elements of this triple threat-varying dialytic removal, phosphate absorption, and phosphate binding-may account for hyperphosphatemia in dialysis patients rather than nonadherence to therapy. Just as the cause(s) of hyperphosphatemia may vary, so too may an individual patient's response to different therapeutic interventions.

6-tips diet: a simplified dietary approach in patients with chronic renal disease. A clinical randomized trial

BACKGROUND

The beneficial effects of dietary restriction of proteins in chronic kidney disease are widely recognized; however, poor compliance to prescribed low-protein diets (LPD) may limit their effectiveness. To help patients to adhere to the dietary prescriptions, interventions as education programmes and dietary counselling are critical, but it is also important to develop simple and attractive approaches to the LPD, especially when dietitians are not available. Therefore, we elaborated a simplified and easy to manage dietary approach consisting of 6 tips (6-tip diet, 6-TD) which could replace the standard, non-individualized LPD in Nephrology Units where dietary counselling is not available; hence, our working hypothesis was to evaluate the effects of such diet vs a standard moderately protein-restricted diet on metabolic parameters and patients' adherence.

METHODS

In this randomized trial, 57 CKD patients stage 3b-5 were randomly assigned (1:1) to receive the 6-TD (Group 6-TD) or a LPD containing 0.8 g/kg/day of proteins (Group LPD) for 6 months. The primary endpoint was to evaluate the effects of the two different diets on the main "metabolic" parameters and on patients' adherence (registration number NCT01865526).

RESULTS

Both dietary regimens were associated with a progressive reduction in protein intake and urinary urea excretion compared to baseline, although the decrease was more pronounced in Group 6-TD. Effects on serum levels of urea nitrogen and urinary phosphate excretion were greater in Group 6-TD. Plasma levels of phosphate, bicarbonate and PTH, and urinary NaCl excretion remained stable in both groups throughout the study. 44 % of LPD patients were adherent to the dietary prescription vs 70 % of Group 6-TD.

CONCLUSIONS

A simplified diet, consisting of 6 clear points easily managed by CKD patients, produced beneficial effects either on the metabolic profile of renal disease and on patients' adherence to the dietary plan, when compared to a standard LPD.

Dietary patterns and clinical outcomes in hemodialysis patients in Japan: a cohort study

Background & Objectives

Little is known about actual dietary patterns and their associations with clinical outcomes in hemodialysis patients. We identified dietary patterns in hemodialysis patients in Japan and examined associations between dietary patterns and clinical outcomes.

Design, setting, participants, measurements

We used data from 3,080 general-population participants in the Hisayama study (year 2007), and data from 1,355 hemodialysis patients in the Japan Dialysis Outcomes and Practice Patterns Study (JDOPPS: years 2005–2007). Food intake was measured using a brief self-administered diet-history questionnaire (BDHQ). To identify food groups with the Hisayama population data, we used principal components analysis with Promax rotation. We adjusted the resulting food groups for total daily energy intake, and then we used those adjusted food-group scores to identify dietary patterns in the JDOPPS patients by cluster analysis (Ward’s method). We then used Cox regression to examine the association between dietary patterns and a composite of adverse clinical outcomes: hospitalization due to cardiovascular disease or death due to any cause.

Results

We identified three food groups: meat, fish, and vegetables. Using those groups we then identified three dietary patterns: well-balanced, unbalanced, and other. After adjusting for potential confounders, we found an association between an unbalanced diet and important clinical events (hazard ratio 1.90, 95% C.I. 1.19–3.04).

Conclusions

Hemodialysis patients whose diet was unbalanced were more likely to have adverse clinical outcomes. Thus hemodialysis patients might benefit not only from portion control, but also from a diet that is well-balanced diet with regard to the food groups identified here as meat, fish, and vegetables.