Chronic kidney disease (CKD) occurs when the kidneys become damaged and slowly lose their ability to filter waste and excess fluids from the blood, causing a buildup of harmful substances in the body.

As kidney damage progresses, people often experience symptoms like swelling, fatigue, chest pain, dry skin, itching, numbness, headaches, shortness of breath, and weight loss. Without proper treatment, chronic kidney disease can lead to bone disease, anemia, stroke, or heart attack.

People with CKD are often placed on a renal (kidney) diet to slow the progression of the disease, relieve symptoms, and maintain nutrient stores. This specialized diet focuses on controlling the intake of specific minerals to protect the kidneys from further damage and balance electrolyte levels.

When following the renal diet, carefully managing your sodium, phosphorus, potassium, and protein intake is essential.

Foods Low in Sodium

Sodium is an essential mineral that helps to maintain fluid balance in the body. However, people with chronic kidney disease should limit sodium intake because excess sodium causes the blood to hold on to more fluids than needed.

Fluid retention increases blood volume, leading to hypertension (high blood pressure). It can cause edema (swelling), shortness of breath, and strain on the heart and kidneys. Further damage may develop as the kidneys work harder to manage the increased fluid load.

Sodium recommendations vary depending on the stage of kidney disease and your individualized health status. A general rule of thumb is to limit your intake to less than 2,300 milligrams daily.

Here are some tips for reducing your sodium intake:

• Season your food with spices, herbs, vinegar, lemon juice, and salt-free seasoning
• Use low-sodium sauces and salad dressings
• Choose unprocessed meats over their processed counterparts
• Choose products labeled “low-sodium” or “sodium-free”
• Select fresh and frozen fruits, vegetables, and protein sources without added seasonings and sauces
• Drain and rinse canned foods that contain added salt

Foods Low in Phosphorus

Phosphorus is a mineral that plays a pivotal role in bone health and energy production. The kidneys help maintain balanced phosphorus levels by filtering extra phosphorus from the blood and excreting it in urine.

Removing excess phosphorous becomes difficult as kidney function declines, leading to phosphorus buildup in people with chronic kidney disease. High phosphorus levels pull calcium out of the bones, weakening bone structure. 

Elevated phosphorus levels can also result in harmful calcium deposits in the lungs, eyes, blood vessels, and heart, increasing the risk of heart attack or stroke. Depending on your phosphorus levels, you may be advised to limit phosphorus intake to 800-1,000 milligrams to reduce these complications.

Foods and drinks low in phosphorus include:

• Fresh fruits and vegetables: Apples, berries, grapes, cucumbers, mushrooms
• Dairy alternatives: Unenriched rice milk and almond milk, vegan yogurt and cheese
• Grains: White bread, pasta, rice, corn and rice cereals
• Beverages: Water, coffee, tea, lemonade, drinks without phosphate additives

Foods Low in Potassium

Potassium is vital for proper nerve, muscle, and kidney function. People with chronic kidney disease typically maintain normal blood potassium levels until reaching the later stages of the disease.

As chronic kidney disease progresses, the kidneys may have difficulty getting rid of excess potassium, leading to hyperkalemia—high potassium levels in the blood. Hyperkalemia can cause muscle weakness, paralysis, nausea, hypotension (low blood pressure), irregular heartbeat, and cardiac arrest. People at risk of hyperkalemia should have their blood levels checked regularly.

Foods low in potassium include:

• Fruits: Apples, pears, peaches, berries, grapes, pineapples, plums, watermelon
• Vegetables: Green beans, asparagus, cabbage, cauliflower, zucchini, corn, eggplant, onions, peas
• Grains: White bread, pasta, rice, grits
• Milk alternatives: Rice milk

Adequate Protein

Protein is required to build and maintain the body’s tissues and organs, heal wounds, and fight infections. Using protein to carry out these vital functions causes the body to produce waste products that end up in the blood. The kidneys are responsible for removing this waste.

For people with chronic kidney disease, too much protein can increase pressure on the kidneys, leading to further kidney damage. Low-protein diets can ease this pressure and reduce the kidney’s workload.

Too little protein can lead to malnutrition, which develops when the body lacks essential nutrients. People on dialysis may need more protein because the treatments remove protein from the blood. Working with a registered dietitian (RD) or registered dietitian nutritionist (RDN) can help ensure you get the right balance of protein to meet your individualized needs.

Here are some general suggestions:

• Eat smaller portions (2-3 ounces) of meat, chicken, and fish
• Keep dairy to a minimum (one-half cup milk or yogurt or one slice of cheese)
• Make plant proteins half of your total protein intake to slow the loss of kidney function

Specific foods to avoid on a renal diet depend on the stage of kidney disease and laboratory test results. People in the early stages are advised to avoid or limit foods high in sodium and protein to reduce kidney strain. In later stages, avoiding foods high in potassium and phosphorus also becomes crucial.

Foods high in sodium include:

• Salt and salt seasonings: Table, seasoning, garlic, onion, celery, and lite salts, meat tenderizer
• Salty foods: Crackers, potato chips, pretzels, tortilla chips
• Cured foods: Ham, bacon, sauerkraut, pickles
• Luncheon meats: Deli meats, pastrami, sausage, spam, hot dogs
• Processed foods: Canned food, TV dinners, frozen prepared food, fast food

Foods high in protein include:

• Animal sources: Meat, chicken, fish, eggs, dairy
• Plant sources: Beans and legumes, nuts, seeds

Although beans, nuts, and seeds contain protein, plant proteins are gentler on the kidneys than animal proteins. Excess acid can harm the kidneys, and plant proteins produce less acid in the body than animal proteins.

Foods and drinks high in phosphorus include:

• Foods with phosphate additives: Foods containing dicalcium phosphate, disodium phosphate, monosodium phosphate, phosphoric acid, trisodium phosphate
• Dairy products: Milk, cheese, yogurt
• Protein sources: Oyster, beef liver, fish roe, sardines, chicken liver, organ meats, processed meats
• Beverages: Beer, cocoa, drinks with phosphate additives, dark sodas
• Other foods: Chocolate, caramels, oat bran (e.g., oat bran muffins)

Foods high in potassium include:

• Fruits: Bananas, apricots, dates, dried fruits, oranges, orange juice, kiwis, honeydew melons
• Vegetables: Potatoes, beans and legumes, acorn and butternut squash,
  artichokes, beets, leafy greens, tomatoes, avocados
• Dairy: Milk, yogurt
• Grains: Bran and bran products, wheat germ, brown rice, nuts, beans, whole-wheat bread and pasta

Below are several kidney-friendly breakfast, lunch, and dinner ideas to enjoy throughout the week.

Breakfast

• Whole egg or egg white omelet with red peppers, zucchini, garlic, and onion
• Homemade pancakes, scrambled egg whites, and mixed berries
• Chia seed pudding made with almond milk and topped with sliced pears

Lunch

• Mediterranean chickpea salad with cucumbers, red onion, and fresh herbs
• Chicken salad with grapes, apples, and onions paired with white bread
• Fish tacos with a side of roasted corn

Dinner

• Grilled chicken (3 ounces) with rosemary cauliflower mash and garlic asparagus
• Baked Salmon (3 ounces) seasoned with dill with a side of green beans and white rice
• Tofu with vegetable fried rice

Snacks

• Celery and peanut butter
• Plain popcorn
• Berry smoothie made with almond milk

The diets researched for their effects on kidney disease are the DASH Diet and plant-based diets.

The DASH Diet, short for Dietary Approaches to Stop Hypertension, is an eating plan designed to lower high blood pressure and slow the progression of heart and kidney disease. It emphasizes consuming fruits, vegetables, whole grains, fish, poultry, beans, seeds, nuts, and low-fat dairy products while limiting sodium, added sugar, saturated fat, and red meat. 

Plant-based diets focus on an increased intake of fruits, vegetables, whole grains, beans, nuts, and seeds while limiting or excluding animal products. These diets are rich in fiber, vitamins, minerals, and antioxidants that lower disease risk. Studies have shown that plant-based diets can slow or completely stop the progression of kidney disease.

Chronic kidney disease is characterized by kidney damage that reduces the ability to eliminate excess waste and fluid. People with the condition are advised to adhere to a strict renal diet to prevent further kidney damage and manage symptoms.

Depending on the stage of kidney disease and laboratory test results, dietary restrictions may include limiting sodium, potassium, phosphorus, and protein intake. Healthcare providers and RDs or RDNs adjust these recommendations to meet each person’s needs. Regularly monitoring and adjusting the diet is necessary to minimize kidney disease progression and maintain mineral balance.