While they don’t receive as much attention as the heart and the brain, kidneys multitask and work hard to keep your other organs, glands, and cells functioning as they should. When the kidneys are damaged, as they are in people with chronic kidney disease (CKD), diet changes are often needed to help keep the kidneys working as best they can for as long as possible. 

Every person’s body is different, however, and trying to figure out what the best kidney-friendly diet is can be frustrating. Here, registered dietitian Candace Mooney explains why there’s no one-of-a-kind diet for everyone who has CKD.*

What Do Your Kidneys Do?

Your kidneys, each one just the size of a fist, play many roles in keeping your body functioning as a whole. Kidneys:

• Control the amounts of minerals in your blood
• Regulate your blood volume by producing urine
• Remove wastes from the breakdown of proteins
• Maintain the pH (acid-base balance) of your blood
• Produce hormones for:
  • Making red blood cells, 
  • Controlling blood pressure, and 
  • Activating vitamin D
• Break down insulin, a hormone that regulates blood sugar

When your kidneys are unable to filter out toxins, wastes, and excess fluids, inflammation increases and causes further damage.

Proteins and Their Role in CKD

Protein management is central to a CKD diet, particularly because the kidneys are responsible for filtering waste products from protein breakdown. “The overall goal for protein is to eat less protein and to eat less animal protein specifically,” Mooney says, since animal proteins place a higher burden on the kidneys. 

Plant-based proteins are preferred because they:

• Result in less waste for the kidneys to process, 
• Reduce inflammation, and 
• Help maintain better blood pH.

Mooney emphasizes that reducing protein intake can also improve bone health and decrease muscle wasting, outcomes for which people with CKD are at higher risk. 

While protein consumption is generally lowered for patients in stages 3 to 5, those on dialysis, or with diabetes-related CKD, might require more protein to avoid malnutrition.

Sodium and Fluid Management

Controlling sodium intake is also necessary for CKD management. Too much sodium can cause fluid retention and increase already high blood pressure. The recommended sodium intake is less than 2,300 milligrams per day for most patients, Mooney explains, but some people, such as those with cardiovascular disease or congestive heart failure, may need to go even lower.

She encourages people to check food labels and limit processed and restaurant foods, which are often high in sodium. “Most of us are getting our sodium from processed foods and restaurant foods,” she says, making these areas key targets for reducing sodium consumption.

Potassium and Phosphorus Considerations

Managing potassium and phosphorus levels is equally important for CKD patients, as the kidneys struggle to filter these minerals effectively as the disease progresses. 

High potassium levels can cause irregular heart rhythms, but Mooney explains that “Plant foods that have potassium do not affect your blood potassium,” making them safer than potassium additives found in processed foods. Those additives, she says, are more readily absorbed and harder for the kidneys to metabolize.

Phosphorus, often found in protein-rich foods, should also be carefully monitored, Mooney cautions, since “phosphorus additives are absorbed at a rate of greater than 90%,” compared to only 50% absorption from plant-based phosphorus. 

When reading food labels, she says, avoid any foods containing “phos” additives, as these can contribute to the progression of:

• Kidney disease, 
• Bone disease, and 
• Hardening of the arteries.

Takeaway

Ultimately, Mooney says, CKD nutrition is highly individualized and should be tailored to each person’s specific kidney function and health status. As she puts it, “there is no one-size-fits-all diet” for CKD, and she encourages patients to work with a renal dietitian to create a personalized plan that addresses their unique dietary needs.

*Mooney, C. (2024, June 5). Why One-Size-Fits-All Doesn’t Work for Renal Diets | CKD Nutrition Webinar [Video file]. Responsum Health. Retrieved from https://www.youtube.com/watch?v=tS-4UTZEkvQ 

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