Dialysis serves as a life-sustaining treatment for individuals experiencing kidney failure, taking over the crucial functions their kidneys can no longer perform. For these patients, dietary management becomes an integral part of their overall treatment plan, directly influencing their health and well-being. A common question concerns food intake during treatment sessions, highlighting the specialized nature of the diet required for those on dialysis. This article explores the relationship between diet and dialysis, outlining the necessary considerations.
Eating During Treatment Sessions
Eating during hemodialysis sessions is not advised due to adverse effects on the patient’s blood pressure. When food is consumed, blood flow is redirected to the gastrointestinal system to aid digestion, which can lead to a rapid decrease in blood pressure and an increased risk of intradialytic hypotension. Consuming more than 200 calories or any fluids during a session can increase the likelihood of hypotension. This redirection of blood flow can also interfere with treatment efficiency.
In contrast, patients undergoing peritoneal dialysis (PD) typically have more flexibility with their diet and can generally eat during treatment. Peritoneal dialysis is performed daily, either manually or with a machine, which means waste and fluid accumulation is less significant between sessions compared to hemodialysis. While eating is permissible, large meals might cause discomfort due to dialysate fluid in the abdominal cavity. Patients on PD may be encouraged to eat more protein and, in some cases, higher potassium foods to compensate for nutrient losses.
General Dietary Principles
The kidneys play a sophisticated role in the body, filtering waste products from the blood, regulating fluid balance, and maintaining electrolyte levels. When kidney function declines to the point of requiring dialysis, these regulatory abilities are significantly compromised. Dialysis treatments remove waste and fluid, but do not fully replicate the continuous filtration of healthy kidneys. Consequently, diet becomes a powerful tool to manage the accumulation of substances that impaired kidneys and intermittent dialysis cannot adequately clear.
A specialized eating plan, often called a “renal diet,” supports dialysis patients by preventing toxin and excess fluid buildup. The primary objectives of this diet are to control fluid and waste accumulation, maintain a stable balance of electrolytes like potassium and phosphorus, and ensure adequate nutrition to prevent muscle wasting and maintain energy. This careful balance involves limiting certain nutrients while ensuring sufficient intake of others, supporting overall health and treatment effectiveness.
Managing Specific Nutrients and Fluids
Potassium management is an important aspect of the renal diet, particularly for hemodialysis patients, because high levels can disrupt heart rhythm and lead to cardiac problems. Healthy kidneys excrete excess potassium, but with impaired function, it can accumulate in the blood. Patients are advised to limit high-potassium foods (e.g., bananas, oranges, potatoes, tomatoes) and choose lower-potassium options (e.g., lettuce, green beans, cucumbers). Potassium binders may be prescribed to reduce absorption.
Phosphorus is another mineral that requires monitoring in dialysis patients, as elevated levels can lead to bone disease, joint pain, and cardiovascular complications. Healthy kidneys remove excess phosphorus, but when function is compromised, it can build up. Foods high in phosphorus include dairy products, nuts, processed meats, and cola drinks. Phosphate binders are commonly prescribed medications taken with meals and snacks to prevent dietary phosphorus absorption.
Sodium intake is controlled to manage fluid retention and high blood pressure, which are issues for dialysis patients. Sodium causes the body to hold onto water, and excessive intake can lead to swelling, shortness of breath, and increased thirst, making fluid restrictions more challenging. Patients are advised to limit sodium to less than 2,300 milligrams per day, often aiming for closer to 1,500 milligrams, by avoiding processed foods, fast food, and added salt. Herbs and spices can flavor meals as salt alternatives.
Protein requirements for dialysis patients are higher than for healthy individuals, ranging from 1.0 to 1.2 grams per kilogram of body weight per day. Both hemodialysis and peritoneal dialysis treatments can lead to protein loss, necessitating adequate, high-quality protein intake to prevent muscle wasting and support health. Good sources include lean meats, poultry, fish, and eggs. Processed meats should be avoided due to their high sodium and phosphorus content.
Fluid restrictions are an important aspect of dialysis management, as impaired kidneys cannot remove excess water. Uncontrolled fluid intake can lead to fluid overload, causing swelling, high blood pressure, and breathing difficulties from fluid in the lungs. Most hemodialysis patients need to limit fluid intake to approximately 32 ounces (about four 8-ounce cups) per day, with allowances based on residual urine output and weight gain between treatments. Patients are encouraged to track fluid intake and use strategies like sipping beverages or consuming ice chips to manage thirst.
Personalized Dietary Guidance
Dietary needs for individuals on dialysis are specific, varying based on the type of dialysis, remaining kidney function, individual lab results, and health status. There is no universal “one-size-fits-all” renal diet that applies to every patient. A registered renal dietitian is an important member of the healthcare team, providing tailored nutritional guidance.
These specialized dietitians assess a patient’s requirements, considering their medical history and lifestyle, to create a personalized meal plan. They offer food recommendations, explain portion sizes, and help patients manage dietary challenges. Adherence to this individualized dietary plan, developed with a renal dietitian, is important for maintaining well-being and optimizing treatment outcomes.