World Kidney Day 2025: The Role of Nutrition and Hydration in Kidney Health

Did you know your kidneys filter 180 litres of blood each day? They get rid of waste and extra water to produce urine. These bean-shaped organs work non-stop to keep your body’s minerals and fluids in check. However, kidneys are delicate and can be affected by things conditions such as diabetes and high blood pressure. This highlights how vulnerable these vital organs can be and how important it is to keep kidneys healthy.  

What you eat and drink has a big impact on supporting or harming your kidney function. Whether you are managing an underlying condition or dealing with kidney disease, it is crucial to understand how food, drinks and kidney health are associated. This blog explores evidence-based recommendations to help you maintain optimal kidney function through smart food choices and proper hydration.

Understanding kidney function and its relationship with diet

Your kidneys perform several life-sustaining functions, such as:

• Filtering waste products from blood
• Balancing electrolytes and minerals
• Regulating blood pressure
• Hormone production that supports red blood cell synthesis
• Activating vitamin D for bone health
• When you consume food and beverages, your kidneys process the nutrients, minerals and fluids. This is why what you eat and drink directly impacts kidney function.

The kidney-diet connection

Following a proper renal diet can significantly slow the progression of kidney disease and improve quality of life. The right diet for kidney disease varies depending on whether you have acute or chronic kidney problems. For those with healthy kidneys, certain dietary patterns can help maintain function and prevent future issues.  

Kidney healthy foods to include in your daily meals

Proper nutrition for kidney health involves balancing protein intake with other essential nutrients. Protein is essential for building and repairing tissues, but too much can overwork damaged kidneys. A kidney-healthy diet typically includes controlled amounts of protein, sodium and phosphorus.

Sodium management

A kidney-healthy diet typically includes controlled amounts of sodium. Increased sodium intake can raise blood pressure and cause fluid retention, both of which stress the kidneys.

• Tips for reducing sodium:
• Cook at home more often
• Use herbs and spices instead of salt
• Read food labels (aim for foods with less than 140mg sodium per serving)
• Rinse canned foods to remove excess sodium
• Choose fresh or frozen vegetables without added sauces

Mineral balance

• Potassium: This mineral helps your nerves and muscles function properly. However, damaged kidneys may not remove excess potassium effectively, leading to potentially dangerous levels in your blood.
• Phosphorus: This mineral helps strengthen bones. When kidneys aren’t functioning properly, phosphorus can build up in your blood, pulling calcium from bones and causing them to weaken.

Foods that support kidney health include:

• Berries: Strawberries, blueberries and raspberries are rich in antioxidants and low in potassium
• Olive oil: Contains anti-inflammatory properties that may benefit kidney health
• Fish: Provides high-quality protein and omega-3 fatty acids
• Egg whites: Offer protein with minimal phosphorus
• Garlic: Helps reduce inflammation and protect kidney tissue
• Red bell peppers: Low in potassium but high in vitamins A, C and B6
• Cabbage: Provides vitamin K, vitamin C and fibre with low potassium content.

Foods to avoid for kidney health protection include:

• Processed foods: Often high in sodium and phosphorus additives
• Salt and high-sodium condiments: Increase blood pressure and fluid retention
• Certain whole grains: Contain high phosphorus levels
• Some fruits and vegetables: Bananas, oranges, potatoes and tomatoes are high in potassium
• Dairy products: Rich in phosphorus and sometimes potassium
• Nuts and seeds: Though nutritious, they’re often high in phosphorus and potassium

Kidney disease diet: Essential guidelines for management

There are several types of kidney disease. The causes of kidney disease vary and may include high blood pressure, infections or genetic factors. Early detection is critical as the symptoms of kidney disease often appear late, making the treatment challenging. Fortunately, kidney disease treatment options exist, including medications, dialysis and lifestyle changes. Under lifestyle modifications, diet and hydration play a significant role in managing the condition.  

• A kidney disease diet should be tailored to your specific condition and stage of kidney function. The dietary approach differs based on:
• Stage of kidney disease: Earlier stages may have fewer restrictions. For instance, research recommends controlled protein intake based on the below category:
• For stable CKD (chronic kidney disease): 0.55–0.6 g/kg/day of protein
• For acute cases: 0.8–2 g/kg/day
• For dialysis patients: Higher protein needs (1.2–1.5 g/kg/day)
• Presence of other conditions: Diabetes, heart disease or high blood pressure
• Treatment approach: Dialysis type or transplant status  
• Individual lab results: Your specific levels of potassium, phosphorus and other markers

Diet for kidney stone prevention

If you’re prone to kidney stones, dietary modifications can help prevent recurrence:

• Increase fluid intake to produce at least 2 litres of urine daily
• Limit sodium to reduce calcium in urine
• Consume adequate calcium from food sources (not supplements)
• Limit oxalate-rich foods if you form calcium oxalate stones
• Reduce animal protein intake
• Limit vitamin C supplements

The science behind hydration and kidney function

Adequate hydration for kidney health helps filter waste products more efficiently. Recent studies have revealed significant correlations between water intake and kidney function preservation.

Research published in the Journal of Nephrology found that higher water intake correlates with a slower decline in estimated glomerular filtration rate (eGFR), a key marker of kidney function. Specifically, tap water consumption showed:

• 1.4 ml/min/1.73 m² improvement after one year
• 1.0 ml/min/1.73 m² improvement after three years

Optimal Water Intake for Kidney Health and Function

Optimal water intake for kidney health varies based on individual factors like weight, activity level and climate. While the traditional ‘8 glasses a day’ recommendation is a good starting point, your needs may differ.

For most people with healthy kidneys, the National Academy of Medicine recommends:

• About 3.7 litres (125 ounces) daily for men
• About 2.7 litres (91 ounces) daily for women

These amounts include all fluids consumed, including those from food.

Special Hydration Considerations

Learning how to stay hydrated for kidney health is essential for maintaining proper kidney function. However, if you have kidney disease, your fluid needs may be different:

• For CKD patients: Your doctor may recommend specific fluid limits
• For kidney stone prevention: Higher fluid intake is often recommended
• For polycystic kidney disease: Increased water intake may slow cyst growth

Conclusion

Kidney health is strongly associated with what you eat and drink. Making informed choices about diet and hydration can potentially slow the progression of kidney diseases. For those with CKD, chronic kidney disease treatment focuses on slowing progression with suitable therapy along with a prescribed diet and fluid intake as recommended by a healthcare provider.