Kidney Diet

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Kidney Diet

Research and general acceptance

Resources

Definition

The kidney diet, also known as the renal diet, is a set of guidelines for people with kidney disease. The types of foods prescribed depend on the level of kidney failure the patient is experiencing, but generally the diet involves controlling the amount of sodium , potassium, phosphorus, protein , and fluid that a person ingests. People with kidney disease should be in consultation with a renal dietitian.

Origins

The kidney diet has been developed and refined by the medical science community, including doctors and hospitals, who have worked with patients with kidney disease. It is based upon scientific research done by many professionals in many different settings, including laboratories, clinics, and hospitals. This research in combination with other available information has been used to develop a set of guidelines to allow patients with kidney failure to eat and drink in a way that helps to manage their disease most effectively.

Description

There is no single kidney diet. The kidney diet is a set of guidelines for patients experiencing some level of kidney failure. Because every kidney patient is unique, each kidney diet may be slightly different. People who have been diagnosed with kidney failure should see a renal dietician to determine the exact specifications of the kidney diet they should follow. Whether a person is experiencing early or late stages of kidney failure, whether they are receiving dialysis treatment and which type, as well as regular nutritional factors such as height, age, and weight will play a role in determining what sort of diet should be followed. In any case, renal patients must be very careful and take their diet seriously. Careful adherence to a kidney diet can lessen the symptoms of kidney failure and prolong the usefulness of the kidneys.

Sodium

Sodium is a mineral found in many foods and is important to many different bodily functions. One of the most important functions of sodium involves maintaining fluid levels. If too much sodium builds up in the body it causes thirst and fluid buildup. Normally functioning kidneys help to maintain proper levels of sodium in the body. If the kidneys begin to fail however, it becomes more important to maintain appropriate levels of sodium intake.

The easiest way to avoid excess sodium intake is to eliminate putting extra salt on foods. People frequently add salt during cooking and at the table. Even just topping these behaviors will usually cut back significantly on the amount of sodium ingested. It is also important to avoid particularly salty foods such as theater popcorn, potato chips, salted pretzels, bacon and other cured meats, and processed cheese. Checking the ingredients list of processed, frozen, and canned foods is a good way to see how much sodium the product contains. Canned soups are often surprisingly high in salt, but often times there are low-sodium alternatives available.

KEY TERMS

Amino acid —Molecules that are the basic building blocks of proteins.

Electrolyte —Ions in the body that participate in metabolic reactions. The major human electrolytes are sodium (Na+), potassium (K+), calcium (Ca 2+), magnesium (Mg2+), chloride (Cl-), phosphate (HPO₄ 2-), bicarbonate (HCO₃-), and sulfate (SO₄ 2-). Ion—An atom or molecule that has an electric charge. In the body ions are collectively referred to as electrolytes.

Mineral —An inorganic substance found in the earth that is necessary in small quantities for the body to maintain a health. Examples: zinc, copper, iron.

Vitamin —A nutrient that the body needs in small amounts to remain healthy but that the body cannot manufacture for itself and must acquire through diet.

Because salt contributes so much to the flavor of foods, it may be helpful to find replacements for it. Using lemon juice or herb mixtures can add flavor without adding sodium, however mixtures such as garlic salt should not be used because they still have contain a high level of sodium. Artificial salt substitutes should also be avoided because these usually contain high levels of potassium, another mineral that people following a kidney diet need to monitor.

Potassium

Potassium is a mineral found in varying amounts in almost all foods, including fruits, vegetables, meat, and dairy products. The body uses potassium for a variety of important functions such as maintaining fluid and electrolyte balance, sending nerve impulse to muscles, and aiding in metabolic processes. When a person’s kidneys are functioning normally they filter out excess potassium, helping to maintain the proper amount in the body. Without properly functioning kidneys, patients need to control their potassium intake.

Avoiding foods with high levels of potassium, while maintaining a healthy diet, can be quite difficult because many fruits and vegetables are high in potassium. Oranges, broccoli, tomatoes, potatoes, and carrots are all high in potassium. Apples, blueberries, grapes, strawberries, lettuce, and onions are all relatively low in potassium. Canned vegetables and the juices they are usually canned are particularly high in potassium. For patients with kidney problems who want to eat certain high potassium vegetables, there is one method for removing some of the potassium, called leaching. This process varies depending on the vegetable, but generally it involves repeatedly rinsing and boiling the vegetable in a large amount of water .

Phosphorus

Phosphorus is another mineral found in many foods. The body must maintain a proper balance of phosphorus and calcium in order to build and preserve healthy bones. Normally, the kidneys help to maintain this balance by removing excess phosphorus from the bloodstream. However, patients with kidney disease may need to take steps to maintain this balance by watching what they eat, because their kidneys are no longer able to do this important job. If too much phosphorus builds up in the body it can pull calcium out of the bones, making them weak and easily breakable.

People following a kidney diet may be told to avoid foods that are high in phosphorus, such as beer, soda, cheese, milk, yogurt, oysters, beans, peas, nuts, and many whole grain products. A renal dietician may also prescribe a phosphate binder, which can help control the amount of phosphate that the body absorbs.

Protein

Proteins are complex organic molecules made of amino acid chains. The body uses these chains to build and maintain muscles, organs, and glands. When the body breaks down protein it produces a waste product called urea. This waste product is usually filtered out by the kidneys and expelled from the body in urine. Patients experiencing kidney failure must be careful about the amount and type of protein they consume because the kidneys are no longer doing a good job of removing urea. If too much urea builds up in the body it can cause serious illness. Patients must be sure to get enough protein however, because without protein the body is not abletoperform proper muscle maintenance.

Before kidney patients begin dialysis treatments, they are usually told to follow a low-protein diet . However, once dialysis treatment begins, a renal dietician will usually tell the patient to consume large amounts of high quality protein, otherwise known as complete protein. While many plants do supply protein, high quality proteins are mainly found in meat and eggs.

Fluid Intake

When patients are experiencing kidney failure, their kidneys are no longer removing water from the body with proper efficiency. The worse that the kidneys are functioning, the more important it is for patients to monitor their fluid intake. Water retention can cause swelling in the feet and ankles, as well as other parts of the body. The most recommended method for preventing water retention is to monitor salt intake, as recommended above.

Function

The function of the kidney diet is to help patients with kidney disease to feel better, limit their symptoms, and slow the development of kidney failure. For people with kidney disease, it is important to maintain the proper balance of electrolytes, minerals, and fluid in the bloodstream. For patients undergoing dialysis treatments, this becomes even more important. This is because the kidneys work to rid the body of excess electrolytes, minerals , and fluid by filtering the blood. When a person’s kidneys are not functioning properly, these substances can build up in the body and cause symptoms such as nausea, vomiting, tiredness, weakness, sleepiness, and other problems. If patients lower their intake of certain substances they can help to control these problems, but if they limit these same substances too severely, they can suffer from malnutrition. The kidney diet is designed to help patients find the best balance for their body.

Benefits

The benefits of the kidney diet are enormous. Patients who have been diagnosed with early to late kidney failure must follow a special diet in order to slow deterioration and lessen their symptoms. Patients who do not follow a special diet will inevitably see their disease become worse more quickly. Patients who do follow this diet usually feel better and can prolong the use of their kidneys.

Precautions

People with any level of kidney failure should be under medical supervision. Patients will usually need to work closely with a renal dietician who can monitor important levels of electrolytes, minerals, and fluids to make sure that patients are maintaining proper nutrition while limiting the load on their kidney and other bodily systems. The diet for dialysis patients is especially strict and should be taken extremely seriously in order avoid further complications.

Risks

While there are risks to following the kidney diet guidelines, they are usually far outweighed by the risks of not following the guidelines. Patients should work with a renal dietician to determine their specific requirements. Dietary supplements will usually be needed to maintain proper nutrition.

A concern for kidney patients is that they maintain proper protein levels. Kidneys, when functioning normally, remove urea, a waste product of protein, from the bloodstream. When kidneys are not functioning properly, urea can build up in the system and make patients ill. Because of this patients with kidney failure need to limit the amount of protein in their diets. However, it is important for patients to not be over-zealous in their limiting of protein, because too getting too little protein can also have serious health consequences.

Patients with kidney disease also run the risk of losing bone calcium due to high phosphorus levels. If patients do not take a phosphate binder, phosphorus in the blood will pull calcium from the bones, making them weak and brittle.

Potassium levels are also important to people with kidney disease. This mineral affects the steadiness of the heartbeat and its level in the bloodstream is normally kept steady by the kidneys. If there is too much potassium in the blood it can be very dangerous for the heart, and possibly even fatal.

Maintaining daily calorie intake is a concern for patients following a kidney diet. With the great number of restrictions placed on the kinds of foods a person can eat it can be difficult for a patient to eat enough calories each day. However if overall caloric intake is not maintained at high enough levels the patient can suffer body tissue breakdown.

If patients with later stages of kidney disease do not pay close attention to their sodium and fluid intake they have a serious risk of retaining water. Fluid can build up and cause painful swelling and weight gain. It also can cause blood pressure to rise which can adversely affect the heart. Kidney disease patients also have a greater risk of heart disease. Following a low-fat diet will usually be necessary.

QUESTIONS TO ASK THE DOCTOR

What kinds of foods should I avoid?
What kinds of foods are best for me?
How severe is my kidney failure?
When should I begin consulting a renal dietician?
Should I consider eating during dialysis?
How will I know what levels of sodium, potassium, fluid, phosphorus, and protein are right for me?
Are there any sign or symptoms that might indicate a problem while on this diet?

Research and general acceptance

The kidney diet is the accepted diet for people with kidney disease, especially those patients who are on dialysis. The is little or no debate that it is essential for patients experiencing kidney failure to closely monitor their diet. A doctor may also prescribe other treatments in addition to a special diet.

Resources

BOOKS

Mitzimberg, Judy. Dialysis Diet. Glendale, AZ: Omni-graphics, 2006.

Shannon, Joyce Brennfleck ed. Diet and Nutrition Source-book. Detroit, MI: Omnigraphics, 2006.

Willis, Alicia P. ed. Diet Therapy Research Trends. New York: Nova Science, 2007.

ORGANIZATIONS

American Dietetic Association. 120 South Riverside Plaza, Suite 2000, Chicago, Illinois 60606-6995. Telephone: (800) 877-1600. Website: <http://www.eatright.org> National Kidney Foundation. 30 East 33rd Street, New York, NY 10016. Telephone: (800) 622-9010. Website: <http://www.kidney.org>.