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Your kidneys don’t function as well as they should when you have Chronic Kidney Disease. Early stages of CKD usually show no symptoms and may only be diagnosed through blood or urine test. Kidneys filter wastes and excess fluids from the blood and then are expelled into the urine. Dangerous levels of fluid, waste, and electrolytes can build up in the body when the CKD advances. 

doctor holding kidneys

The waste build-up may be gradual that the body gets used to having those wastes in the blood. After months or years, CKD may progress to permanent kidney failure that requires a kidney transplant or regular dialysis.

The Role of Nutrition in CKD

A healthy balanced renal diet can slow down the progression of kidney disease. It is also essential in providing energy, preventing infection, avoiding muscle-mass loss, and helping maintain a healthy weight. There is no universal meal plan that is appropriate for people with CKD. What you are allowed to eat depends on your CKD stage. Your renal diet also depends if you have underlying conditions such as diabetes or heart conditions. You can ask your doctor or a registered renal dietitian to customize your diet based on your lab tests and lifestyle.

What Nutrients Should I Watch Out For?

It is a fact that your body needs a diverse amount of nutrients and minerals to function properly. But in the case of CKD, however, too much sodium, potassium, protein, and phosphorus (SPPP) can harm your kidneys. Furthermore, you may even need to limit other nutrients if you are already in the advanced stage of CKD. Therefore, the sooner you manage SPPP in the early stages of CKD, the more your Quality of Life (QoL) will improve-- even with CKD.

Sodium and CKD

Sodium is both an electrolyte and mineral whose major role is to help keep the water and other electrolytes balanced in the body. Its other great role is in how nerves and muscles work. Sodium also helps regulate blood pressure, blood volume, and pH balance. The sodium levels in the body are partly controlled by a hormone in the body called aldosterone. This hormone instructs the kidneys when to hold sodium in the body rather than passing it in the urine. 

sodium word cut in paper

Admittedly, most foods have natural sodium or have sodium (from salt) as an ingredient in cooking. In fact, many medicines and products such as aspirin, mouthwash, and toothpaste have sodium too. 

It is why, if your kidneys aren’t functioning well, high sodium levels can also result in high blood pressure, edema (swelling in the ankles, legs, hands, and face), shortness of breath, and heart failure. 

How to Limit Your Sodium Intake

limit sodium in sticky notes

The recommended sodium consumption for a healthy adult is no more than 2300 mg per day which is equivalent to 1 teaspoon of salt. People with CKD or high blood pressure are recommended to limit their sodium intake ranging from 750 mg - 2000 mg per day.  Your exact limit should be advised by your primary healthcare provider.

Sodium is virtually found in almost all food including fruits and vegetables. Lessening your sodium intake doesn’t mean eating bland food. You can still enjoy the flavor in a low sodium diet using herbs and spices such as cumin, thyme, paprika, cinnamon, or cardamom.  There are, of course, a number of other herbs and spices that might just entice you to try them.

Reading the food label can also help you reduce your sodium intake. Consider the serving size and the milligrams of sodium per serving when reading the food label. Compare and differentiate the sodium content of similar brands before choosing a product.  Avoiding the foods on the list, below,  could further help you manage your sodium intake and stay within your recommended limit:

High Sodium Food List

  • Condiments – sodium content ranges from 150–900 mg per serving.
  • Sauces – barbecue sauce can add over 150mg per tablespoon while soy sauce can have 900 mg of sodium per tablespoon.
  • Tomato Sauce – a quarter of a cup of tomato sauce can have 400mg sodium. Watch over your pasta, pizzas, and soups. 
  • Seasonings – can have up to 690 mg per serving. Check the nutrition label on seasoning blends as they may have salt when you least expect it. 
  • Canned Vegetables – a half-cup serving yields 300mg sodium. Go for “no added salt” options. 
  • Pickles – are preserved vegetables in a salt solution that can have a 785 mg sodium content.
  • Breakfast cereals - a cup serving of breakfast cereals can have 220 mg sodium.
  • Processed meats – Deli meats, sausages, and hot dogs can have an estimated sodium intake of 500–1,000 mg per 2 oz serving. Cured meats and condiments can contribute to your daily sodium intake.

Protein and CKD

Protein bolsters the immune system to fight infections. It helps repair and build the body’s tissues, provides the body with a structural framework, and maintains proper pH and fluid balance. Excess protein in the body can cause nausea, appetite loss, weakness, and taste changes. The more protein in the body, the harder your kidneys work to remove the waste. 

Following a low protein diet puts less stress on your kidneys. Meanwhile, people on dialysis need a higher amount of protein in their diet to maintain blood protein levels. Dialysis treatment removes protein waste from the blood, so a low protein diet is no longer needed

protein diet and foods

How to Manage Protein Intake

The exact amount of protein your body needs vary depending on the stage of your condition, body size, and nutritional status. Too little protein can lead to malnutrition and (muscle) wasting.  KDIGO, a non-profit organization advocating for evidence-based clinical practice in managing kidney disease, suggests a lowering protein diet of  0.6 to 0.8 g/kg a day to manage CKD. Those with diabetes and chronic kidney diseases are recommended to have a daily protein intake of 0.8-1 g/kg. Meanwhile, diabetic patients should not reduce protein intake to less than 1 g/kg of body weight.

A study published in the American Journal of Kidney Diseases (AJKD) suggests that eating plant-based protein sources instead of animal sources could improve the health of people with declining kidney function. The National Kidney Foundation (NKF) also suggests that CKD patients who follow a plant-based diet can slow down the progression of their kidney disease. Evidently, a plant-based diet could lower blood pressure, cholesterol level, and the risk of heart disease. Following a plant-based diet further nourishes the body with antioxidants (e.g. Vitamins C and E), preventing cell damage.  

Before switching to a plant-based diet or any dietary changes, consult your doctor or renal dietitian first. They can recommend the right amount of (daily) protein intake and guide you as you embark on your kidney diet. A few of the top plant-based food sources include soy products, beans and legumes, tofu, nuts and seeds, and whole grains.

plant based foods

Potassium and CKD

Potassium is an important mineral that regulates blood pressure, maintains fluid and electrolyte balance, and supports muscle contractions. When you have CKD, however, your kidneys have a reduced capacity to keep your blood potassium at healthy levels. 

Too much potassium can lead to hyperkalemia, a medical condition that causes numbness, tiredness, irregular heartbeat (that could lead to a heart attack), nausea, poor appetite, and difficulty in breathing. There are plenty of factors that can increase the potassium level in the body. These factors include a high potassium diet, certain medications, and uncontrolled diabetes.

potassium foods

How to Manage Potassium Content

The National Kidney Foundation suggests that 1,500-2,700 mg of potassium taken daily can help maintain good health without impacting the kidneys. You can reduce the potassium content in vegetables by following certain cooking methods including:

Double Boiling

Also called leaching, double boiling extracts and dissolves potassium in a liquid. You can leach potatoes or sweet potatoes by following these steps:

  1. Peel and place the vegetable in cold water (to avoid darkening).
  2. Slice the vegetables into 1/8-inch-thick pieces and briefly rinse in warm water.
  3. Soak the vegetables in warm water for a minimum of 2 hours. Use ten times the amount of water to the amount of vegetables (e.g., 10 cups of water for 1 cup of potatoes).
  4. Rinse the vegetables in warm water again for a few seconds.
  5. Cook vegetables. Use five times the amount of water to the number of vegetables (e.g., 5 cups of water for 1 cup of vegetables)
potatoes in boiling water

After leaching, the amount of potassium ranges from 100 to 200 milligrams in half a cup serving. Consequently, you can also reduce the potassium content of these vegetables by cutting, slicing thinly, or grating them.

Soak and Cook

Soaking legumes such as beans, peas, lentils, and peanuts can reduce potassium and phosphorus content.  However, you still need to watch out for proper portioning. 

Alternately, apart from following the cooking methods above, you can stay within your recommended daily potassium intake by consciously limiting or avoiding high potassium foods: 

  • Nuts
  • beans and legumes
  • bananas
  • potatoes
  • most dairy products
  • avocados
  • salty foods
  • fast foods
  • processed meats
  • bran and whole grains
  • spinach
  • cantaloupe and honeydew
  • tomatoes
  • vegetable juices

Phosphorus and CKD

The body uses phosphorus to form strong bones and teeth, maintain a normal pH balance, change protein, fat, and carbohydrate into energy, and develop connective tissues and organs. 

Damaged kidneys allow phosphorus to build up in the blood. Too much phosphorus pulls calcium from the bones, which can weaken the bones, cause joint pain and calcify the blood vessels.

How to Manage Phosphorus Content

As CKD progresses, a patient may need to take a phosphate binder to control the phosphorus in the blood. These binders act like sponges to soak up or bind, phosphorus while it is in the stomach. The phosphorus does not get into the blood since it is “bound.”

Phosphorus found in animal foods is absorbed more easily compared to plant-based phosphorus. Inorganic phosphorus that is added in fast foods, ready-to-eat foods, canned and bottled drinks, cured meats, and most processed foods is completely absorbed by the body. 

It is, therefore, ideal to read the nutrition facts of the food, at the back of the label, if you are looking to manage or limit your phosphorus intake. Also wise to steer clear from products with phosphorus additives such as:

  • Calcium phosphate
  • Dicalcium phosphate
  • Disodium phosphate
  • Monosodium phosphate
  • Sodium hexameta-phosphate
  • Sodium acid pyrophosphate
  • Sodium tripolyphosphate
  • Trisodium phosphate
  • Sodium tripolyphosphate
  • Tetrasodium pyrophosphate

Limiting your consumption of these high phosphorus foods can also keep your phosphorus level within range.  

  • Dairy foods (milk, cheese, yogurt)
  • Beans (baked, kidney, lima, pinto)
  • Nuts and peanut butter
  • Processed meats (hot dogs, canned meat)
  • Cola
  • Canned iced teas and lemonade
  • Bran cereals
  • Egg yolk

The Bottom Line

These nutrients are essential and play great roles in maintaining and preserving bodily functions. Learning and understanding the nutrient content of your food helps you stay in check within your daily recommended intake. You can start by reading the nutrition labels at the back of the food products. Essentially, monitoring your lab results allows you to see whether you are making progress or getting worse. This prompts you, then, to make adjustments in your food choices and lifestyle.

When in doubt, talk to your doctor or registered renal dietitian for more guidance and to customize meal plans based on your dietary needs.