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Why is a Healthy Diet Crucial in Kidney Disease?

Updated: Nov 6, 2023


Nutritious diet is vital especially in chronic kidney disease (CKD) because a healthy diet:

  1. Provides fuel needed to complete daily activities

  2. Prevents infection

  3. Prevents loss of muscular mass.

  4. Aids in preserving a healthy weight

  5. Reduces the rate of renal (kidney) disease progression.

What are the fundamentals of a healthy diet?

 

A recommended daily intake of protein, calories, vitamins, and minerals is obtained from a balanced diet. Maintaining health and wellbeing requires a healthy diet, regular exercise, and proper adherence to all prescribed medications.



Does the diet need to change in kidney disease?

 


The kidneys keep the balance of minerals and nutrients in the body in check. If a dog, cat or human has kidney disease, the kidneys are not able to carry out this function very well, therefore, a number of dietary adjustments need to be made. The adjustments are made based on lifestyle and lab tests. The changes in the diet are to help control high blood pressure and to keep the kidney disease from getting worse



What dietary changes are needed in a kidney patient?

 
A Maltese dog and a cat eating organic food
A Maltese dog and a cat eating balanced organic food

The diet of a kidney patient changes over time, depending on the kidney's function and other factors, e.g., if the patient also follows a special diet for diabetes or heart conditions, that needs to be continued.

The diet of a kidney patient needs to have the amounts of following controlled:-

  1. Protein

  2. Sodium

  3. Potassium

  4. Phosphorus

  5. Calcium

When a kidney patient consumes the right amount of nutrients helps control waste and fluid buildup in the blood, reducing the kidneys' workload to remove excess fluid. If kidney disease worsens, other nutrients may need to be limited based on blood test results.


Protein

 

Protein is essential for muscle building, tissue repair, and infection prevention.

Controlling protein intake is crucial for dogs with chronic kidney disease (CKD) due to several important reasons specific to their condition. CKD is a progressive condition in which the kidneys lose their ability to effectively filter waste products and maintain fluid and electrolyte balance. Here's why controlling protein intake is advised for cats and dogs with CKD:


1. Reducing Kidney Workload: Protein metabolism results in the production of waste products, including urea and creatinine, which are normally excreted by the kidneys. In CKD, the kidneys are less efficient at clearing these waste products. By reducing protein intake, there is less nitrogen waste produced, which can help reduce the workload on the compromised kidneys.


2. Minimizing Proteinuria: Proteinuria, the presence of excess protein in the urine, is common in dogs with CKD. It can contribute to further kidney damage. By providing a controlled amount of high-quality, easily digestible protein, the amount of protein that ends up in the urine minimized.


3. Managing Phosphorus Levels: Protein-rich foods also tend to be high in phosphorus. High phosphorus levels can exacerbate kidney damage in dogs with CKD. Controlling protein intake can indirectly help manage phosphorus levels in the diet, which is crucial for dogs with CKD.


4. Preventing Malnutrition: While it's important to restrict protein, it's equally important to ensure that the protein provided is of high quality and easily digestible. This helps prevent malnutrition and maintains muscle mass, which is vital for overall health and well-being.


5. Avoiding Protein Overload: Excessive protein intake can potentially lead to an overload of nitrogenous waste products, which the compromised kidneys may struggle to handle.

Sodium

 

A low-sodium diet is often advised for patients with chronic kidney disease (CKD) for several important reasons. CKD is a progressive condition in which the kidneys gradually lose their ability to filter waste and maintain fluid and electrolyte balance. Here's why a low-sodium diet is recommended for CKD patients:


1. Blood Pressure Management: High sodium intake is associated with elevated blood pressure (hypertension), which can further damage the kidneys and accelerate the progression of CKD. Controlling blood pressure is a crucial aspect of CKD management, as it helps preserve kidney function.


2. Fluid Retention: Excess sodium in the diet can lead to fluid retention in the body. CKD patients often have compromised kidney function, making it difficult to eliminate excess fluid. This can result in swelling (edema) and increased strain on the heart.


3. Electrolyte Balance: Sodium is an electrolyte, and maintaining proper electrolyte balance is essential for overall health. CKD can disrupt the balance of electrolytes in the body, leading to complications like hyperkalemia (high potassium levels) and metabolic acidosis. Reducing sodium intake helps mitigate these imbalances.


4. Cardiovascular Health: CKD patients are at higher risk of cardiovascular problems. A low-sodium diet can help reduce the risk of heart-related complications by lowering blood pressure and fluid retention.


5. Minimizing Proteinuria: Proteinuria, the presence of excess protein in the urine, is common in CKD. A low-sodium diet may help reduce proteinuria, which is beneficial for kidney health.


Potassium

 

Potassium, essential for muscle function, can be dangerously low or high in the blood. Its level depends on kidney function and medication usage. Commercial renal diets with the right potassium levels are available for dogs and cats.


Potassium restriction in pets with chronic kidney disease (CKD) is a crucial aspect of managing their condition. In CKD, the kidneys lose their ability to filter waste products and maintain electrolyte balance effectively. Here's why potassium restriction is necessary:


1. Hyperkalemia Risk: In CKD, the impaired kidney function can lead to a buildup of potassium in the bloodstream, a condition known as hyperkalemia. High potassium levels can have serious consequences, including cardiac arrhythmias and muscle weakness.


2. Cardiac Health: Elevated potassium levels can negatively impact the heart's electrical activity, potentially leading to life-threatening arrhythmias. This is particularly dangerous for pets with compromised kidney function, as their hearts may already be under stress.


3. Muscle Function: High potassium levels can affect muscle function, causing weakness or even paralysis. This can significantly impact a pet's quality of life.


4. Bone Health: Potassium imbalance can contribute to disturbances in calcium and phosphorus metabolism, which can worsen bone health issues common in pets with CKD.

Phosphorus

 

Phosphorus restriction is a critical dietary component for pets with chronic kidney disease (CKD). The kidneys play a central role in regulating phosphorus levels in the body, and in CKD, this regulation becomes impaired. Here's why phosphorus restriction is advised for pets with CKD:


1. Phosphorus Excretion: Healthy kidneys filter excess phosphorus from the blood and excrete it through urine. In CKD, the kidneys' ability to perform this function declines, leading to a buildup of phosphorus in the bloodstream.


2. Hyperphosphatemia: Elevated phosphorus levels in the blood, known as hyperphosphatemia, can have several detrimental effects. It can lead to mineral imbalances, particularly with calcium, which can contribute to soft tissue calcification, a condition that can harm organs and tissues.


3. Secondary Hyperparathyroidism: High phosphorus levels can stimulate the parathyroid glands to release parathyroid hormone (PTH). PTH increases calcium release from bones and reduces calcium absorption from the intestines. This can lead to decreased bone density and skeletal abnormalities.


4. Progression of Kidney Disease: Elevated phosphorus levels can further damage the kidneys, contributing to the progression of CKD. It can lead to tubular damage, inflammation, and fibrosis in the kidneys.


5. Minimizing Clinical Signs: Restricting dietary phosphorus can help minimize clinical signs associated with CKD, such as lethargy, inappetence, and nausea. It can also slow the progression of the disease.


Specialized renal diets formulated for pets with CKD are designed to control phosphorus levels while still providing essential nutrients.


Calcium

 

Restricting calcium in the diet of pets with chronic kidney disease (CKD) is a complex matter, as it involves a delicate balance. While it's not typically necessary to restrict calcium in the same way as phosphorus, there are important considerations to keep in mind. Here's why calcium restriction may be necessary in some cases:


1. Phosphorus Control: In pets with CKD, controlling phosphorus levels is a primary concern, as elevated phosphorus can further damage the kidneys and contribute to the progression of the disease. Calcium and phosphorus are closely interrelated, so managing both is crucial.


2. Calcium-Phosphorus Balance: Maintaining an appropriate calcium-to-phosphorus ratio in the diet is essential. Excessive dietary calcium can lead to an imbalance and interfere with phosphorus absorption and excretion. This can exacerbate renal damage in CKD patients.


3. Soft Tissue Mineralization: High levels of calcium in the bloodstream can lead to soft tissue mineralization. This can result in calcification of organs and tissues, which can be harmful to pets with CKD.


4. Parathyroid Gland Regulation: CKD can disrupt the regulation of calcium and phosphorus by the parathyroid glands. This can lead to secondary hyperparathyroidism, where the body tries to compensate for imbalances, but it can have detrimental effects on bone and overall health.



What about fluids in kidney patients?

 

Fluid therapy illustration for kidney disease
Fluid therapy illustration for kidney disease

Fluid management is a critical aspect of caring for both human and pet patients with kidney disease, particularly chronic kidney disease (CKD). Proper fluid intake is important to support kidney function, prevent dehydration, and manage various complications associated with kidney disease. Here are some key considerations regarding fluid management for kidney patients:


1. Hydration: Maintaining adequate hydration is crucial for kidney function. Dehydration can lead to decreased blood flow to the kidneys, potentially worsening kidney function. Adequate hydration is essential for pets with CKD. Proper hydration supports kidney function and helps prevent dehydration, which can worsen kidney damage. Pet owners should encourage their pets to drink water regularly. This can be achieved by providing fresh water, using pet fountains, or adding water to their food. In some cases, veterinarians may prescribe subcutaneous fluid therapy to help maintain hydration in pets with CKD. This involves injecting fluids under the skin, which can be done at home or at the veterinary clinic.


2. Fluid Restriction: In some cases of advanced CKD or when fluid retention is a concern (e.g., in heart failure), fluid intake may need to be restricted. This restriction is typically determined on an individual basis by a healthcare provider.


3. Electrolyte Balance: Fluid management is closely linked to maintaining a balance of electrolytes, such as sodium and potassium, in the body. Proper electrolyte levels are critical for overall health.


4. Monitoring Weight: Regularly monitoring a pet's weight can help detect changes in hydration status. Sudden weight loss or gain can be indicative of fluid retention or dehydration.


5. Specialized Renal Diets: Some commercial pet foods are formulated to have higher moisture content, which can help with hydration in pets with CKD.



What about calories for kidney patients?

 

Managing calorie intake in dogs with chronic kidney disease (CKD) is an essential aspect of their dietary management. It's important to strike a balance between providing enough calories to maintain a healthy body weight and not overloading the kidneys with excessive protein and other waste products. Here's why calorie management is important in CKD dogs:


1. Weight Maintenance: Dogs with CKD may experience weight loss and muscle wasting as the disease progresses. Providing the right amount of calories helps maintain a healthy body weight and muscle mass, which is essential for overall well-being.


2. Avoiding Malnutrition: While protein intake is restricted in CKD dogs, calories should still be provided to meet their energy needs. This helps prevent malnutrition and provides the energy necessary for daily activities.


3. Monitoring Body Condition: Regular monitoring of the dog's body condition and weight is crucial. Adjustments to calorie intake may be necessary over time, especially if the dog loses or gains weight.


4. Minimizing Phosphorus: Many high-calorie foods are also high in phosphorus, which can be detrimental to dogs with CKD. Selecting calorie-dense but low-phosphorus foods can help manage phosphorus levels.


5. Monitoring Protein and Other Nutrients: In addition to calories, it's important to monitor the dog's protein and nutrient intake. Specialized renal diets formulated for dogs with CKD are available and are designed to meet their nutritional needs while managing protein and phosphorus levels.


Consultation with a Veterinarian to determine the appropriate calorie intake for a CKD dog is important so that the dog's individual needs, stage of CKD, and overall health can be considered.


Are vitamins and mineral supplements necessary for kidney patients?

 

Vitamins, minerals and protein supplements
Vitamins, minerals and protein supplements

In both human and veterinary medicine, the use of supplements for kidney patients, particularly those with chronic kidney disease (CKD), is a subject of careful consideration. While some supplements may be beneficial, others can potentially exacerbate kidney issues. Here are some key points to consider regarding supplements for kidney patients:


1. Water-Soluble Vitamins: Water-soluble vitamins like B-complex vitamins (e.g., B1, B2, B6, B12) and vitamin C are generally safe for kidney patients and may be supplemented if there is a deficiency. However, excessive doses should be avoided.


2. Fat-Soluble Vitamins: Fat-soluble vitamins (A, D, E, K) should be used with caution in kidney patients. These vitamins are processed by the liver and may accumulate in the body if kidney function is compromised. Any supplementation should be carefully monitored.


3. Omega-3 Fatty Acids: Omega-3 fatty acids from fish oil can have anti-inflammatory effects and may be beneficial for kidney patients. However, the dosage should be carefully regulated, and consultation with a veterinarian is advised.


4. Phosphorus Binders: In advanced stages of CKD, when phosphorus levels become elevated, phosphorus binders may be prescribed to help control phosphorus absorption from the diet.


5. Potassium: Depending on the individual case, potassium supplements may be necessary for pets with CKD. However, this should be carefully monitored, as elevated potassium levels can be harmful.


6. Calcitriol or Vitamin D Analogs: In some cases of advanced CKD, supplementation with calcitriol or vitamin D analogs may be necessary to help regulate calcium and phosphorus metabolism.


7. Herbal Supplements and Alternative Therapies: Many herbal supplements and alternative therapies have not been thoroughly studied in the context of kidney disease. Therefore, their use should be approached with caution and under the guidance of a veterinarian.


Any decision to use supplements for kidney patients should be made in consultation with a veterinarian. They can provide tailored advice based on the individual's specific health status, stage of kidney disease, and potential interactions with medications.

References

 

Polzin, D. J. (2011). Chronic Kidney Disease in Dogs and Cats. The Veterinary Clinics of North America. Small Animal Practice, 41(1), 15-30.


Ross, S. J., Osborne, C. A., Kirk, C. A., Lowry, S. R., Koehler, L. A., & Polzin, D. J. (2006). Clinical evaluation of dietary modification for treatment of spontaneous chronic kidney disease in cats. Journal of the American Veterinary Medical Association, 229(6), 949-957.


Bartges, J. W. (2012). Chronic Kidney Disease in Dogs and Cats. Veterinary Clinics: Small Animal Practice, 42(4), 669-692.


Elliott, J., & Barber, P. J. (1998). Feline chronic renal failure: Clinical findings in 80 cases diagnosed between 1992 and 1995. Journal of Small Animal Practice, 39(2), 78-85.


Kidney Disease: Improving Global Outcomes (KDIGO) Blood Pressure Work Group. (2012). KDIGO Clinical Practice Guideline for the Management of Blood Pressure in Chronic Kidney Disease. Kidney International Supplements, 2(5), 337-414.


National Kidney Foundation. (2002). K/DOQI Clinical Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification, and Stratification. American Journal of Kidney Diseases, 39(2 Suppl 1), S1-266.

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