Dialysis is a medical procedure that takes over the function of failing kidneys, cleaning the blood by removing waste products and excess fluid from the body. Since the kidneys can no longer manage the balance of minerals and water, a patient’s diet becomes an extension of the medical treatment. Whether eating is permissible during this process depends entirely on the type of dialysis received and the individual’s specific health condition. Understanding these dietary guidelines is fundamental to successfully managing life with kidney failure.
Eating During the Dialysis Session
For patients undergoing in-center hemodialysis, the most common type, eating a full meal during the treatment session is generally discouraged for physiological reasons. When a person eats, blood naturally rushes to the stomach and intestines to begin digestion and nutrient absorption. During hemodialysis, the machine is already removing a large volume of fluid from the bloodstream, which reduces overall blood pressure.
This diversion of blood flow to the gut can cause a sudden drop in blood pressure, known as intradialytic hypotension. This can lead to unpleasant symptoms like cramping, nausea, vomiting, or dizziness, and may require the session to be stopped early. Prematurely ending the treatment means that waste products and excess fluid are not adequately removed, reducing dialysis effectiveness.
Some centers may permit a small, approved snack, particularly for diabetic patients who need to prevent low blood sugar. Permitted foods must be low in potassium, as the dialysis process cannot remove potassium from food eaten during the session. Patients using Peritoneal Dialysis (PD) often have fewer restrictions, as this method continuously removes waste products over a longer period. PD patients generally have greater flexibility with their diet and may eat during the exchange process, though they still must adhere to long-term dietary guidelines.
Essential Dietary Restrictions for Kidney Health
The long-term diet of a dialysis patient focuses on controlling four major components: potassium, phosphorus, sodium, and fluid intake. Managing these substances prevents dangerous build-up between treatment sessions. A buildup of potassium (hyperkalemia) is dangerous because it can interfere with the heart’s electrical signals, potentially causing an irregular heartbeat or cardiac arrest.
Foods high in potassium must be limited or avoided. Phosphorus, another mineral normally excreted by the kidneys, must also be controlled, as high levels pull calcium from the bones, making them weak and brittle. Excess phosphorus can also cause painful joints, itchy skin, and calcium deposits in soft tissues and blood vessels.
To control phosphorus, patients are often advised to avoid:
- Processed meats
- Dark-colored sodas
- Whole grains
- Nuts
- Most dairy products
Patients often take phosphate binders, medications that attach to phosphorus in the stomach to prevent absorption into the bloodstream.
Sodium restriction is necessary because salt causes the body to retain water, increasing thirst and leading to fluid overload. Uncontrolled fluid retention between sessions can cause swelling, high blood pressure, and strain on the heart, leading to difficulty breathing. Sodium intake should be limited to less than 2,300 milligrams per day, roughly equivalent to one teaspoon of salt. Processed foods, canned goods, and salty snacks are the primary sources of excess sodium.
Strategies for Successful Meal and Fluid Management
The most effective approach to managing the dialysis diet is to work closely with a renal dietitian who can personalize guidelines based on individual blood test results and treatment type. Patients are encouraged to track their fluid intake, which includes anything that melts at room temperature, such as ice, soup, and gelatin. Many patients must limit their fluid intake to 32 ounces or less per day, depending on residual kidney function.
To manage the intense thirst caused by sodium restriction, several strategies can be implemented. Sucking on frozen items like ice chips, lemon wedges, or frozen grapes provides relief while minimizing fluid consumption. Using mouthwash or sugar-free hard candies can also help combat dry mouth and reduce the urge to drink.
For controlling sodium, patients should focus on cooking meals from scratch using fresh ingredients and flavoring foods with herbs, spices, garlic, or lemon juice instead of salt. Since processed foods are often high in both sodium and phosphorus additives, choosing fresh fish, poultry, and lean meats is a better alternative. Simple food swaps can significantly reduce potassium and phosphorus.