Is Protein Bad for Kidneys?

Published on: 03/14/2024

The amount and type of protein you need if you have chronic kidney disease (CKD) is an important topic of discussion. In fact, it’s one of the most important concepts to wrap your brain around.

What is protein?

Proteins are the building blocks of life. Every cell in the human body contains protein. You need protein in your diet to help your body repair cells and make new ones. Protein is also important for growth and development. Proteins are made of long chains of amino acids. 

Some amino acids can be made by our bodies and for that reason are considered non-essential amino acids.  But some amino acids cannot be made by our bodies and have to be obtained from food. These are called essential amino acids. 

Because of this need for essential amino acids, even people who need to restrict their protein intake for health reasons (such as CKD)  cannot cut out protein from their diets completely.

Protein is one of the three macronutrients our bodies need to function.  The other two are carbohydrates and fats. In other words, protein, carbohydrates, and fats are the only nutrients that provide energy (in the form of calories) to our bodies.  Each macronutrient is important, but protein is especially important. 

why protein restriction in kidney disease?

While protein is essential, too much protein can be damaging to your kidneys if they are already compromised. 

High protein consumption has been found, under various conditions, to lead to glomerular hyperfiltration (filtering blood at a faster rate than normal) and hyperemia (increased blood flow); acceleration of chronic kidney disease (CKD); increased proteinuria (protein in the urine); blood pressure changes; increased risk for kidney stones; and various metabolic alterations.

How much protein should you eat if you have kidney disease?

The amount of protein recommended for individuals without kidney disease is a controversial subject.  The Recommended Daily Allowance (RDA) is 0.8 g/kg of body weight, or 0.36 g/lb.  This is the minimum amount of protein needed by people with healthy kidneys, but the maximum is debatable. You can find all sorts of higher recommendations depending on who you listen to, but the evidence for whether or not a high protein diet is damaging for people with normally functioning kidneys is not yet clear.

However, for people with CKD, the verdict is in. We know that excessive protein intake when you already have damaged kidneys can accelerate kidney function decline. Because of this, the National Kidney Foundation’s Kidney Disease Outcomes Quality Initiative (KDOQI) has established some pretty firm guidelines for protein intake. 

For adults in CKD stages 3-5 without diabetes, protein intake should be 0.55-0.6 g/kg total, and for adults in CKD stages 3-5 with diabetes, protein intake should be 0.6-0.8 g/kg total.  

Plant versus animal sources

While we know that limiting overall protein intake can help slow kidney function decline, it is still up for debate whether going completely plant-based is better than consuming some animal protein.  Animal sources of protein contain all the essential amino acids, while plant-based proteins are sometimes lacking the essential amino acids. 

Increasing your plant intake, however, is beneficial, and can go hand-in-hand with reducing your intake of animal-based foods, even if you don’t eliminate them altogether.

Some of the known benefits of increasing your plant intake include increased fiber intake, reduced metabolic acidosis, and decreased blood pressure, and each of these ultimately contribute to the slowing of kidney function decline.

Have you heard of ketoanalogues?

I mentioned that essential amino acids have to be obtained through food; however, there is another way to get those essential amino acids besides food, and they’re called ketoanalogues. 

Amino acids are made of hydrogen, oxygen, carbon, and nitrogen. Nitrogen is the part that is damaging to the kidneys. Ketoanalogues are essential amino acids that have been separated from their nitrogen component.  

Using ketoanalogues is one way to ingest essential amino acids without taxing your kidneys.  They are taken with meals like a medicine to provide essential amino acids. If you are willing to eliminate animal products from your diet, ketoanalogues may be for you.  They can help meet your protein needs to prevent malnutrition, while preventing excess work for your kidneys. This is one more way to preserve kidney function. You can learn more here. 

What should you do now?

Following a low protein diet is a risky undertaking.  Often, doctors hesitate to recommend a low protein diet to their patients with CKD because of fears of malnutrition. For some people, a protein restricted diet is not recommended at all due to other conditions.  It is essential to work with a registered dietitian who specializes in CKD to help you determine whether you really should be following a low protein diet and to ensure you’re covering all the bases. 

If you are ready to talk about how I can help you gain clarity in what to eat, overcome food fears, and stay off dialysis, schedule a call or reply to this email. I would love to hear from you!

References:

Protein in Diet. Medline Plus. https://medlineplus.gov/ency/article/002467.htm

Ko, Gang-Jee. (2020, July 15). Pubmed. The Effects of High-Protein Diets on Kidney Health and Longevity.

https://pubmed.ncbi.nlm.nih.gov/32669325/#:~:text=High%20dietary%20protein%20intake%20can,lead%20to%20de%20novo%20CKD.

Ikizler, T. Alp. (2020, September). American Journal of Kidney Diseases. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update.

https://www.ajkd.org/article/S0272-6386(20)30726-5/fulltext#secsectitle0300

(2022, February). Kidney Nutrition Institute. https://kidneynutritioninstitute.org/mediterranean-diet-and-kidney-health/

Friedman, A. (2004, December). High Protein Diets: Potential Effects on the Kidney in Renal Health and Disease. American Journal of Kidney Diseases.  https://www.ajkd.org/article/S0272-6386(04)01253-3/abstract

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Meet Heather
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Although I’ve been a dietitian for more than 20 years, it’s the past few years that have convinced me to take control of my own health by changing the way I eat. So many chronic illnesses can be corrected or prevented through good nutrition. I am thankful to have the opportunity to walk with people in my community, Beaufort, SC and beyond, through their own journeys as they reclaim their health.

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