Historically, eating during the hemodialysis treatment has been associated with increased risk for adverse intradialytic symptoms and events, risks that have resulted in the implementation of restrictive in-center nutrition policies. Recent studies, however, have recorded a shift in clinical practice with a higher proportion of physicians following the view that administration of intradialytic meals and supplements represents a simple and effective approach to enhance caloric intake and improve nutritional status among patients on hemodialysis. This shift towards less restrictive in-center nutrition practices is mainly supported by evidence from observational studies associating intradialytic nutritional supplementation with improvements in protein-energy wasting, inflammatory state, and health-related quality of life. In sharp contrast, earlier and recent interventional studies have documented that feeding during the hemodialysis treatment provokes a rapid postprandial decline in blood pressure and raises the incidence of symptomatic intradialytic hypotension. Furthermore, other studies have shown that postprandial redistribution in intravascular volume and enhanced blood supply to the gastrointestinal circulation may interfere with the adequacy of the delivered hemodialysis. Those who defend the position that intradialytic nutritional support is beneficial do not dispute the physiology of postprandial hemodynamic response, but they argue against its clinical significance. In this article, we provide an overview of studies that explored the effect of eating during the hemodialysis treatment on intradialytic hemodynamic stability and adequacy of the delivered hemodialysis. We reason that these risks have important clinical implications that are not counteracted by anticipated benefits of this strategy on caloric intake and nutritional status.

Whether hemodialysis patients should be allowed or even encouraged to eat during dialysis remains a controversial topic. This cross-over study aimed to evaluate the impact of feeding during dialysis on intradialytic blood pressure (BP) profile and dialysis adequacy in 26 patients receiving thrice-weekly, in-center hemodialysis. Over three consecutive mid-week dialysis sessions, intradialytic BP was monitored using the Mobil-O-Graph device (IEM, Stolberg, Germany). Blood samples were also obtained for the determination of the urea reduction ratio (URR). At baseline, patients underwent dialysis without the provision of a meal. In phases A and B, a meal with either high-protein (1.5 gr/kg of body weight) or low-protein (0.7 gr/kg of body weight) content was administered 1 h after the initiation of dialysis. The sequence of meals (high-protein and low-protein or vice versa) was randomized. Average intradialytic systolic BP (SBP) was similar on all three occasions. However, compared with baseline, the standard deviation (SD) (11.7 ± 4.1 vs. 15.6 ± 7.6 mmHg, p < 0.01), coefficient of variation (CV) (9.5 ± 3.7% vs. 12.4 ± 6.0%, p < 0.01) and average real variability (ARV) (9.4 ± 3.9 vs. 12.1 ± 5.2 mmHg, p < 0.01) of intradialytic SBP were higher in phase A. Similarly, compared with the baseline evaluation, all three indices of intradialytic SBP variability were higher in phase B (SD: 11.7 ± 4.1 vs. 14.1 ± 4.5 mmHg, p < 0.05; CV: 9.5 ± 3.7% vs. 11.1 ± 3.8%, p < 0.05; ARV: 9.4 ± 3.9 vs. 10.9 ± 3.9 mmHg, p < 0.05). Compared with dialysis without a meal, the consumption of a high-protein or low-protein meal resulted in a lower URR (73.4 ± 4.3% vs. 65.7 ± 10.7%, p < 0.001 in phase A and 73.4 ± 4.3% vs. 67.6 ± 4.3%, p < 0.001 in phase B, respectively). In conclusion, in the present study, feeding during dialysis was associated with higher intradialytic SBP variability and reduced adequacy of the delivered dialysis.

Background/Objectives: Phenylketonuria (PKU) is an inborn error of metabolism (IEM) that requires a specialized medical nutrition therapy (MNT) to maintain blood phenylalanine concentrations within a safe range. This study aimed to assess nutrition practices, knowledge, and PKU diet adherence in patients with PKU. Methods: This cross-sectional study included 27 patients (n = 19 women) with PKU, recruited from clinics of IEM in Greece, ranging in age between 14 and 60 years, with PKU diagnosis via neonatal screening. Each participant completed the questionnaire independently. For the two patients with age below 18 years old, caregivers provided written informed consent. All participants were questioned regarding their dietary practices, nutritional knowledge, and perceptions. Results: More than half (66.7%) of patients complied with the PKU diet and the recommended daily protein substitutes. However, 25.9% reported being unaware of their blood phenylalanine levels, and 40.7% didn’t know how many PKU exchanges they consumed daily. Most patients (88.8%) perceived the recommended PKU diet as “healthy”, and reported feeling well when adhering to it. Several concerns were raised regarding protein substitutes, with 10.5% of patients feeling that the amount of prescribed protein substitutes was too high, while 25.9% perceived it as being too low. Additionally, 14.8% of patients expressed concerns regarding the protein amount required for building muscle mass. Overall, the majority of participants perceived the PKU diet as being adequate in energy, carbohydrates, lipids, and protein. Conclusions: Although patients with PKU generally possess a good understanding of PKU nutritional principles, significant potential for improvement in dietary education is apparent. To support optimal management of blood phenylalanine concentrations, it is essential to implement novel communication strategies that facilitate patient adherence to the MNT for PKU. Such strategies should also empower caregivers to provide effective support, including the proper use of protein substitutes and accurate protein exchanges.