Debbie Benner

Understanding Sources of Dietary Phosphorus in the Treatment of Patients with Chronic Kidney Disease

In individuals with chronic kidney disease, high dietary phosphorus (P) burden may worsen hyperparathyroidism and renal osteodystrophy, promote vascular calcification and cardiovascular events, and increase mortality. In addition to the absolute amount of dietary P, its type (organic versus inorganic), source (animal versus plant derived), and ratio to dietary protein may be important. Organic P in such plant foods as seeds and legumes is less bioavailable because of limited gastrointestinal absorption of phytate-based P. Inorganic P is more readily absorbed by intestine, and its presence in processed, preserved, or enhanced foods or soft drinks that contain additives may be underreported and not distinguished from the less readily absorbed organic P in nutrient databases. Hence, P burden from food additives is disproportionately high relative to its dietary content as compared with natural sources that are derived from organic (animal and vegetable) food proteins. Observational and metabolic studies indicate nutritional and longevity benefits of higher protein intake in dialysis patients. This presents challenges to providing appropriate nutrition because protein and P intakes are closely correlated. During dietary counseling of patients with chronic kidney disease, the absolute dietary P content as well as the P-to-protein ratio in foods should be addressed. Foods with the least amount of inorganic P, low P-to-protein ratios, and adequate protein content that are consistent with acceptable palatability and enjoyment to the individual patient should be recommended along with appropriate prescription of P binders. Provision of in-center and monitored meals during hemodialysis treatment sessions in the dialysis clinic may facilitate the achievement of these goals.

Association of Dietary Phosphorus Intake and Phosphorus to Protein Ratio with Mortality in Hemodialysis Patients

BACKGROUND AND OBJECTIVES Epidemiologic studies show an association between higher predialysis serum phosphorus and increased death risk in maintenance hemodialysis (MHD) patients. The hypothesis that higher dietary phosphorus intake and higher phosphorus content per gram of dietary protein intake are each associated with increased mortality in MHD patients was examined. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Food frequency questionnaires were used to conduct a cohort study to examine the survival predictability of dietary phosphorus and the ratio of phosphorus to protein intake. At the start of the cohort, Cox proportional hazard regression was used in 224 MHD patients, who were followed for up to 5 years (2001 to 2006). RESULTS Both higher dietary phosphorus intake and a higher dietary phosphorus to protein ratio were associated with significantly increased death hazard ratios (HR) in the unadjusted models and after incremental adjustments for case-mix, diet, serum phosphorus, malnutrition-inflammation complex syndrome, and inflammatory markers. The HR of the highest (compared with lowest) dietary phosphorus intake tertile in the fully adjusted model was 2.37. Across categories of dietary phosphorus to protein ratios of <12, 12 to <14, 14 to <16, and > or =16 mg/g, death HRs were 1.13, 1.00 (reference value), 1.80, and 1.99, respectively. Cubic spline models of the survival analyses showed similar incremental associations. CONCLUSIONS Higher dietary phosphorus intake and higher dietary phosphorus to protein ratios are each associated with increased death risk in MHD patients, even after adjustments for serum phosphorus, phosphate binders and their types, and dietary protein, energy, and potassium intakes.

Quality-of-Life and Mortality in Hemodialysis Patients: Roles of Race and Nutritional Status

BACKGROUND AND OBJECTIVES Maintenance hemodialysis (MHD) patients often have protein-energy wasting, poor health-related quality of life (QoL), and high premature death rates, whereas African-American MHD patients have greater survival than non-African-American patients. We hypothesized that poor QoL scores and their nutritional correlates have a bearing on racial survival disparities of MHD patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We examined associations between baseline self-administered SF36 questionnaire-derived QoL scores with nutritional markers by multivariate linear regression and with survival by Cox models and cubic splines in the 6-year cohort of 705 MHD patients, including 223 African Americans. RESULTS Worse SF36 mental and physical health scores were associated with lower serum albumin and creatinine levels but higher total body fat percentage. Spline analyses confirmed mortality predictability of worse QoL, with an almost strictly linear association for mental health score in African Americans, although the race-QoL interaction was not statistically significant. In fully adjusted analyses, the mental health score showed a more robust and linear association with mortality than the physical health score in all MHD patients and both races: death hazard ratios for (95% confidence interval) each 10 unit lower mental health score were 1.12 (1.05-1.19) and 1.10 (1.03-1.18) for all and African American patients, respectively. CONCLUSIONS MHD patients with higher percentage body fat or lower serum albumin or creatinine concentration perceive a poorer QoL. Poor mental health in all and poor physical health in non-African American patients correlate with mortality. Improving QoL by interventions that can improve the nutritional status without increasing body fat warrants clinical trials.

Dietary Assessment of Individuals with Chronic Kidney Disease

Examining the quality and quantity of food intake by appropriate methods is critical in the management of patients with chronic kidney disease (CKD). The four commonly used dietary assessment methods in CKD patients include short‐term dietary recalls, several days of food records with or without dietary interviews, urea kinetic based estimates such as protein nitrogen appearance calculation, and food histories including food screeners and food frequency questionnaires (FFQ). There are a number of strengths and limitations of these dietary assessment methods. Accordingly, none of the four methods is suitable in and of itself to give sufficiently accurate dietary information for all purposes. Food frequency questionnaires, which is the preferred method for epidemiological studies, should be used for dietary comparisons of patients within a given population rather than individual assessment. Food histories including FFQ and dietary recalls may underestimate important nutrients, especially in CKD patients. Given the large and increasing number of dialysis patients and work responsibilities of renal dietitians, routine analysis of dietary records and recalls is becoming less feasible. Ongoing and future studies will ascertain additional strengths and limitations of dietary assessment methods in CKD populations including the assessment of food intake during an actual hemodialysis treatment.

Dietary Omega-3 Fatty Acid, Ratio of Omega-6 to Omega-3 Intake, Inflammation, and Survival in Long-term Hemodialysis Patients

BACKGROUND Mortality in long-term hemodialysis patients is high, mostly attributed to cardiovascular events, and may be related to chronic inflammation. We hypothesized that the anti-inflammatory benefits of higher dietary intake of omega-3 compared with omega-6 polyunsaturated fatty acids may modulate the inflammatory processes and decrease death risk. STUDY DESIGN Prospective cohort study using linear and Cox proportional regressions. SETTING & PARTICIPANTS 145 hemodialysis patients from 8 DaVita dialysis clinics in Southern California in 2001-2007. PREDICTORS Intake of dietary omega-3 and ratio of omega-6 to omega-3 using 3-day food record supplemented by dietary interview. OUTCOMES 1-year change in serum C-reactive protein (CRP) level and 6-year survival. RESULTS Patients were aged 53 ± 14 years (mean ± SD) and included 43% women and 42% African Americans. Median dietary omega-3 intake, ratio of omega-6 to omega-3 intake, baseline serum CRP level, and change in CRP level over 1 year were 1.1 (25th-75th percentile, 0.8-1.6) g/d, 9.3 (25th-75th percentile, 7.6-11.3), 3.1 (25th-75th percentile, 0.8-6.8) mg/L, and +0.2 (25th-75th percentile, -0.4 to +0.8) mg/L, respectively. In regression models adjusted for case-mix, dietary calorie and fat intake, body mass index, and history of hypertension, each 1-unit higher ratio of omega-6 to omega-3 intake was associated with a 0.55-mg/L increase in serum CRP level (P = 0.03). In the fully adjusted model, death HRs for the first (1.7-<7.6), second (7.6-<9.3), third (9.3-<11.3), and fourth (11.3-17.4) quartiles of dietary omega-6 to omega-3 ratio were 0.39 (95% CI, 0.14-1.18), 0.30 (95% CI, 0.09-0.99), 0.67 (95% CI, 0.25-1.79), and 1.00 (reference), respectively (P for trend = 0.06). LIMITATIONS 3-day food record may underestimate actual dietary fat intake at an individual level. CONCLUSIONS Higher dietary omega-6 to omega-3 ratio appears to be associated with both worsening inflammation over time and a trend toward higher death risk in hemodialysis patients. Additional studies including interventional trials are needed to examine the association of dietary fatty acids with clinical outcomes in these patients.

Kidney insufficiency and nutrient-based modulation of inflammation.

Purpose of reviewPatients with chronic kidney disease have a high cardiovascular mortality rate. Despite recent advances in dialysis techniques, over 20% of US dialysis patients die every year. Protein–energy malnutrition and inflammation are common and usually concurrent in chronic kidney disease patients, and have been implicated as the main cause of high mortality. We reviewed the pathophysiology of the malnutrition–inflammation complex syndrome and its potential modulation by dietary and other nutritional interventions in chronic kidney disease patients. Recent findingsThe malnutrition–inflammation complex syndrome is a main cause of the atherosclerotic cardiovascular disease epidemic in chronic kidney disease. This may be by virtue of the syndromes inflammatory components. Malnutrition and inflammation lead to weight loss over time, i.e. cachexia in slow motion, and result in decreased serum cholesterol and homocysteine levels. A ‘reverse epidemiology’ of cardiovascular risk factors is observed in chronic kidney disease, in that obesity, hypercholesterolemia and hyperhomocysteinemia are paradoxically associated with better survival. Among the possible etiologies of the malnutrition–inflammation complex syndrome, anorexia, low nutrient intake and oxidative stress are theoretically amenable to dietary modulation; however, the bulk of findings are epidemiological. SummaryThere is no consensus as to how to correct the malnutrition–inflammation complex syndrome in chronic kidney disease patients. Because the malnutrition–inflammation complex syndrome is multifactorial, its correction probably requires a battery of simultaneous interventions, rather than one single modality. Clinical trials focusing on the syndrome are currently non-existent and are therefore urgently required to improve poor clinical outcome in chronic kidney disease patients.

Academy of Nutrition and Dietetics and National Kidney Foundation: Revised 2014 Standards of Practice and Standards of Professional Performance for Registered Dietitian Nutritionists (Competent, Proficient, and Expert) in Nephrology Nutrition

Compelling evidence indicates that the incidence of chronic kidney disease (CKD) is increasing because of an aging population and a higher prevalence of cardiovascular disease, diabetes, and hypertension. Nutrition management of patients with CKD requires early disease recognition, appropriate interpretation of the markers and stages of CKD, and collaboration with other health care practitioners. Better management of CKD can slow its progression, prevent metabolic complications, and reduce cardiovascular related outcomes. Caring for patients with CKD necessitates specialized knowledge and skills to meet the challenges associated with this growing epidemic. The Academy of Nutrition and Dietetics Renal Dietitians Practice Group and the National Kidney Foundation Council on Renal Nutrition, with guidance from the Academy of Nutrition and Dietetics Quality Management Committee, have updated the 2009 Standards of Practice in Nutrition Care and Standards of Professional Performance as a tool for registered dietitian nutritionists working in nephrology nutrition to assess their current skill levels and to identify areas for additional professional development in this practice area. The Standards of Practice apply to the care of patients/clients with kidney disease. The Standards of Professional Performance consist of six domains of professionalism, including: Quality in Practice, Competence and Accountability, Provision of Services, Application of Research, Communication and Application of Knowledge, and Utilization and Management of Resources. Within each standard, specific indicators provide measurable action statements that illustrate how nephrology nutrition principles can be applied to practice. The indicators describe three skill levels (ie, competent, proficient, and expert) for registered dietitian nutritionists working in nephrology nutrition.

Dietary egg whites for phosphorus control in maintenance haemodialysis patients: a pilot study.

BACKGROUND High dietary protein intake is associated with greater survival in maintenance haemodialysis (MHD) patients. High-protein foods may increase dietary phosphorus burden, which is associated with increased mortality in these patients. Hypothesis is: an egg white based diet with low phosphorus to protein ratio (<1.4 mg/g) will lower serum phosphorus without deteriorating the nutritional status in MHD patients. OBJECTIVE We assessed serum phosphorus and albumin levels in MHD patients who agreed to ingest one meal per day with pasteurised liquid egg whites without phosphorus additives, as principal protein source. METHODS Thirteen otherwise stable MHD patients with serum phosphorus >4.0 mg/dl agreed to consume eight ounces (225 g) of pasteurised liquid egg whites one meal per day for six weeks. Recipes were suggested to improve diet variety. RESULTS Thirteen participating patients included seven women, three African Americans and five diabetics. Twelve patients exhibited drop in serum phosphorus. Mean population fall in serum phosphorus was 0.94 mg/dl, i.e. from 5.58 ± 1.34 (mean ± SD) to 4.63 ± 1.18 (p = 0.003). Serum albumin showed an increase by 0.19 g/dl, i.e. from 4.02 ± 0.29 to 4.21 ± 0.36 g/dl (p = 0.014). Changes in phosphorus pill count were not statistically significant (p = 0.88). The egg white diet was well tolerated, and recipe variety appreciated. CONCLUSION Pasteurised liquid egg whites may be an effective diet component lowering serum phosphorus without risking malnutrition. Controlled trials are indicated to examine egg white based dietary interventions in MHD patients at home or during haemodialysis treatment.

Low Protein Nitrogen Appearance as a Surrogate of Low Dietary Protein Intake Is Associated with Higher All-Cause Mortality in Maintenance Hemodialysis Patients

To determine the association between all-cause mortality and dietary protein intake in patients with chronic kidney disease, we performed a large-scale, 8-y prospective cohort study in 98,489 maintenance hemodialysis patients from a multicenter dialysis care provider. Compared with the reference level (60 to <70 g/d), low protein nitrogen appearance (PNA) levels [<30 g/d, HR: 1.40 (95% CI: 1.30, 1.50); 30 to <40 g/d, HR: 1.33 (95% CI: 1.28, 1.39)] was associated with higher all-cause mortality, and high PNA levels [≥110 g/d, HR: 0.92 (95% CI: 0.88, 0.97); 100 to <110 g/d, HR: 0.87 (95% CI: 0.82, 0.91)] were associated with lower all-cause mortality in all analyses. This association was also found in subanalyses performed among racial and hypoalbuminemic groups. Hence, using PNA as a surrogate for protein intake, a low daily dietary protein intake is associated with increased risk of death in all hemodialysis patients. Whether the association between dietary protein intake and survival is causal or a consequence of anorexia secondary to protein-energy-wasting/inflammation or other factors should be explored in interventional trials.

Results of a Pilot Program to Improve Phosphorus Outcomes in Hemodialysis Patients

OBJECTIVE End-stage renal disease causes dysregulation of bone and mineral metabolism, including increased serum phosphorus levels. Kidney Foundation Kidney Disease Outcome Quality Initiative 2003 guidelines recommend maintaining phosphorus levels between 3.5 and 5.5 mg/dL in dialysis patients. We examined the effects of a focused phosphorus management pilot program designed to improve the percentage of hemodialysis patients achieving phosphorus levels <5.5 mg/dL. DESIGN, SETTING, SUBJECTS, AND INTERVENTION: We conducted a prospective, multicenter, single-arm study at 8 geographically diverse at-risk facilities (n = 702 hemodialysis patients) in a large U.S. dialysis organization. The focused phosphorus management program provided in-service training to staff members, and provided patients with diet and phosphorus management through in-center, 1:1 education and support, direct-to-patient adherence communications, benefit management assistance, and adherence support specific to lanthanum carbonate over a 6-month period. MAIN OUTCOME MEASURE Facility-level markers of bone and mineral metabolism (phosphorus, parathyroid hormone, corrected calcium) and nutritional status (serum albumin, normalized protein catabolic rate) were assessed before and after program implementation. RESULTS There was a significant increase in the percentage of patients per facility achieving phosphorus levels <5.5 mg/dL (mean ± SD at baseline = 61.6% ± 5.2%; month 6 = 71.3% ± 9.0%; P < .01) and parathyroid hormone (150 to 300 pg/mL; mean ± SD at baseline = 39.1% ± 2.4%; month 6 = 44.5% ± 7.0%; P = .04). During the course of the evaluation, mean calcium, albumin, and normalized protein catabolic rate levels did not change significantly. CONCLUSIONS These results show proof-of-concept that a focused phosphorus management program targeting both staff members and patients can significantly improve patient outcomes without compromising nutritional status.