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

Abstract

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.

Comparison of creatinine index and geriatric nutritional risk index for nutritional evaluation of patients with hemodialysis

“…Recently, several studies reported that nutritional status was closely associated with morbidity and mortality in chronic HD patients . Therefore, convenient and objective tools such as CI and GNRI facilitate timely and serial assessment of nutritional status.…”

“…Recently, several studies reported that nutritional status was closely associated with morbidity and mortality in chronic HD patients. 10,11 Therefore, convenient and objective tools such as CI and GNRI facilitate timely and serial assessment of nutritional status. In this study, CI facilitated the differential diagnosis of chronic HD patients with normal nutritional status from HD patients with malnutrition when tracked over a period of 4 months.…”

The screening score of Mini Nutritional Assessment (MNA) is a useful routine screening tool for malnutrition risk in patients on maintenance dialysis

“…Most scoring systems for malnutrition use parameters that might be less reliable or less representative in patients on dialysis, and their relation with mortality in this population might be counterintuitive. The most striking example is the obesity paradox that higher BMI appears to be protective in patients on dialysis [5]. Therefore, it is essential that malnutrition scores are validated in dialysis patients, using mortality as outcome.…”

“…Malnutrition is an important and prevalent problem affecting 16% to 70% of dialysis patients, depending on the study population and assessment procedure [1][2][3]. In dialysis patients, insufficient nutritional intake, compromised clinical well-being, comorbidity and dialysis related factors can lead to poor nutritional status [4][5][6]. Poor nutritional status is on its turn associated with impaired functional capacity, increased risk of complications, lower quality of life and limited survival [3,[7][8][9].…”

Lack of Awareness of Dietary Sources of Phosphorus Is a Clinical Concern

“…Is phosphate restriction harmful?There is a concern that phosphate restriction may result in worse outcomes (43)(44)(45)(46). Previously, phosphate restriction placed more emphasis on protein restriction, which may lead to malnutrition, and an even worse prognosis, since malnutrition results in high mortality in hemodialysis patients (47). Therefore, we should instead consider reducing phosphate intake without restriction of protein consumption.…”