The Dialysis Diet: What It Is & Why It's Necessary
Diet and nutrition are a vital part of living well with kidney disease and/or failure. A dialysis (or renal) diet is one that is prescribed for people who have chronic renal failure and are on dialysis. It could also be prescribed to someone who has been given a diagnosis of imminent kidney failure, meaning that their kidneys will eventually fail. It is designed to control how much potassium, sodium, phosphorus, calcium, and fluids a person ingests. There is no one type of diet that is suited to everyone, but there are general guidelines. Your doctor and dietician will help tailor a regimen that suits your specific needs.
Consult Your Doctor
Your doctor and dietician will help tailor a regimen that suits your specific needs.
Potassium (K or KCl) is a mineral that protects blood vessels from damage and keeps vessel walls from thickening. Once inside the body, potassium becomes an ion and functions as an electrolyte. Electrolytes contribute to the regulation of many life-sustaining processes, such as maintaining normal blood pressure, nerve function and muscle contraction. Potassium also assists in carbohydrate and protein metabolism. According to the National Kidney Foundation, a potassium restricted diet is typically about 2,000mg per day. With this recommendation in mind, ultimately, your doctor should always determine your ideal potassium intake based on your nutrition needs and current health status. Early symptoms of high potassium levels, which is called hyperkalemia, include muscle weakness, numbness and tingling in the fingers and toes. If potassium levels continue to increase, it can lead to heart palpitations and an irregular heartbeat. If you don’t immediately receive medical attention, the heart will stop beating without any warning. Most fruits and vegetables are high in potassium, so make choices like apples, grapes, pineapple, green beans, summer squash, bell peppers and onions. These choices tend to have lower potassium counts, and still provide many of the other vitamins and minerals that the body needs to stay healthy. Be sure to check with your dietician for daily serving sizes. Avoid things that are the very high in potassium like bananas, oranges, cantaloupe, mangoes, potatoes, legumes, peas, spinach, dried fruits and tomatoes. Milk products and chocolate products also tend to be high in potassium. Each month, when you receive your lab results from the dialysis center, a “safe” potassium level will be between 3.5 and 5.0.
When most people hear sodium (Na), they think of table salt. Salt is the mineral compound sodium chloride (NaCl). Foods may contain sodium chloride (salt) or may contain sodium in other forms. It can be tricky identifying the different forms of sodium, so talk with your dietician to get help identifying the many other forms. Following a low-sodium diet means limiting salt and other ingredients that contain high amounts of sodium. Sodium is one of the body’s major electrolytes and helps control the fluids going in and out of the body’s tissues and cells. Sodium also contributes to the regulation of blood pressure and blood volume, helps with the transmission of impulses for nerve function and muscle contraction and the regulation of the acid-base balance of blood and other body fluids. As a guideline, if you’re doing in-center hemodialysis, it is recommended that you keep your sodium intake to between 1,200mg and 2,000mg per day. Too much sodium can be harmful for people with kidney disease because the kidneys can no longer eliminate excess sodium and fluid from the body. As sodium and fluids build up in the bloodstream and body tissues, blood pressure increases. There are several other sodium-related complications such as edema which is swelling in the legs, hands, face and other extremities, heart failure due to excess fluid in the bloodstream that can overwork the heart weakening and/or enlarging it and shortness of breath that is caused by fluid building up in the lungs, which makes it difficult to breathe. Once you reach the point where you require dialysis, you will be asked to follow a low-sodium diet. The diet will help control blood pressure and fluid retention in the body and its tissues. Controlling sodium intake will help avoid cramping and blood pressure drops during dialysis. It is imperative that you work closely with your dietitian who will determine how much sodium you can eat each day and counsel you on regulating it in your diet. There are numerous salt substitutes out there today. Ask your dietitian before you start using any of these salt substitutes because some of them may contain potassium, which needs to be limited on a renal diet. The list of food items that are high in sodium is lengthy. Some of the things that should be avoided include table salt, processed foods and cured meats, cheese, pickles, sauces and salads dressings and snack foods (like potato chips). You can get a more comprehensive list from your dietician at your dialysis center.
Phosphorus (P) is a mineral that is necessary for building and maintaining strong bones and teeth as well as a healthy metabolism. The kidneys remove excess phosphorus from the body through the urine. Unfortunately, when your kidneys have failed and you require dialysis, they are no longer able to remove excess phosphorus from the body. Dialysis removes some of the phosphorus from your blood, but it’s inefficient. In order to prevent serious complications, you must balance your phosphorus level through diet, dialysis and medications. When you get your monthly lab results, the normal phosphorus level in the blood is between 3.5 and 5.0. When the level of phosphorus is higher than this range, calcium is pulled from your bones and teeth to form calcium-phosphorus crystals, which are deposited in the blood vessels, skin, and organs. This can cause itching, skin sores, weakened bones and stiff blood vessels. The risk of heart failure and death are significantly increased. The National Kidney Foundation (NKF) recommends that chronic kidney disease patients limit their daily phosphorus intake to 800mg to 1,000mg per day. Foods high in phosphorus that should be limited or avoided are dairy products, beer, dark colas, organ meats (i.e. liver), processed meats, dried beans or peas, nuts, seeds, quick breads, bran and whole-grain products. In addition to the foods naturally high in phosphorus, many processed foods are high in the mineral due to phosphate additives. It’s important to read food labels and avoid foods with phosphates listed on the ingredient list. You can consult your dietician for assistance with identifying hidden phosphorus. Because so many foods contain phosphorus, it is often extremely difficult to control phosphorus levels with only diet and dialysis. Your doctor will more than likely prescribe a medication called a phosphate binder, such as Tums®, Renvella ®, or PhosLo ®. These medications should be taken with all meals and snacks (taken before you eat) because they bind with phosphorus and remove it from your body in the stool. Your dietician will have valuable information on food alternatives that are lower in phosphorus as well as offer tips on limiting your phosphorus intake.
Almost 99% of the calcium (Ca) in the body is in bones and teeth. The rest is found in blood and soft tissues. The body uses calcium to build/maintain strong bones and teeth, to help muscles contract and relax during normal body movement, to transmit nerve impulses, to make the blood clot normally, to regulate cell division and cell multiplication and to assist with enzyme reactions within the body.
Vitamin D and parathyroid hormone (PTH) help manage how much calcium is absorbed for use by the body and eliminated by the kidneys. Healthy kidneys turn vitamin D into an active hormone called calcitriol, which helps increase calcium absorption from the intestines into the bloodstream. When you’re kidney function has been compromised (i.e. chronic kidney disease or kidney failure), these things have to be managed by dialysis, medications, and dialysis. Chronic kidney disease (CKD) causes certain imbalances in bone metabolism and increases the risk of a particular bone disease called renal osteodystrophy, which causes such symptoms as bone deformities, joint and bone pain, bone fractures, and decreased mobility. These imbalances can also cause calcium deposits in the blood vessels and contribute to heart disease. Your doctor will measure your calcium, phosphorus and PTH levels to determine what course of treatment may be required to stabilize your calcium levels. If calcium levels are low, a calcium supplement may be prescribed or there may be the use of calcium-based phosphorus binders to treat both low calcium and high phosphorus levels. When a dialysis patient gets his or her monthly lab results, a normal calcium level will range between 8.5 and 10.5. Of course, this will vary from patient to patient but should generally fall within this range.
When a person is on hemodialysis, it is necessary to be on a fluid restriction. It’s important to follow this restriction very closely because it can help you feel more comfortable before, during and after dialysis treatments. It’s true that dialysis gets rid of excess fluid, however, it’s not as effective as healthy kidneys that work all day, every day. Most people on hemodialysis get treatments at least three times a week for approximately three or more hours for each treatment. Therefore, on the days between treatments, the body holds on to excess fluid. By exceeding recommended fluid allowances given to you by the doctor and dietician, there will likely be swelling and your blood pressure rise, which makes your heart work harder. There will be too much fluid built up in the lungs, causing difficulty breathing and even congestive heart failure or pneumonia. There is a limit to how much fluid can be safely removed during a dialysis treatment, so if the fluid allowance is exceeded, the need for an extra dialysis treatment may become necessary in order to remove all the extra fluid in a safe manner. Generally speaking, a person on dialysis should restrict their fluid intake to about 1 liter a day. This is equivalent to approximately 34-36oz., or 1,000cc (1cc =1ml). Also, keep in mind that anything that is liquid at room temperature should be counted as fluid intake such as ice, ice cream/popsicles, Jell-O, and gravy just to name a few. Some of the complications that can be a result of ingesting too much fluid between treatments are:
high blood pressure, or hypertension
sudden drops in blood pressure that can occur during a hemodialysis treatment
Shortness of breath
Swelling, particularly in feet, hands, and even the face
Fluid buildup in the lungs
Heart problems like a weakened heart muscle and/or an enlarged heart
Sources of Fluid
The Need for a Restricted Diet
Doctors and dieticians strongly recommend that dialysis patients follow a restricted diet. It isn’t meant as a form of punishment or torture. Rather, it’s meant as a way to improve the quality of the patients’ lives and as a means of being healthier on dialysis. The diet will aid in making dialysis treatments more effective, will help you feel your best, and will help to avoid other health complications that can be managed and possibly avoided by doing so. The dialysis diet includes a balance of nutrients that will help keep your body healthy and strong, while allowing the levels of potassium, phosphorus, calcium, sodium and fluids to remain safe. This will improve clearance rates associated with each dialysis treatment, which means they are an acceptable amount of fluid and other waste products efficiently.