Confused about foods to avoid with CKD?

You’ve been diagnosed with chronic kidney disease (CKD) or recently been told that your kidney function has declined. And it’s got you worried. As a proactive person, you’re trying to find out what you can do about it. But all you’ve come away with is a head full of questions. You’re confused about foods to avoid with CKD.

The purpose of this article is to clear up some of the confusion you’re feeling. We’ll address the most common seeming contradictions in the information out there.

Why the contradictions?

There are several reasons that one list says one thing and another list says another thing.

In 2020, the KDOQI (Kidney Disease Outcomes Quality Initiative) guidelines were updated. These guidelines changed many of the previous dietary interventions that had been recommended.  

For example, in the past, people with CKD had been told to avoid whole grains and eat refined grains instead such as white bread and white rice.  So some lists still contain those recommendations. But the practice of eating refined grains over whole grains is no longer recommended. 

CKD ranges from stage 1 to stage 5. Stage 1 is mild compromise and 5 is end stage renal disease (ESRD). The dietary factors you need to focus on at stage 2 CKD vs. stage 4 CKD are likely very different. 

But when you’re doing an internet search, sometimes it’s not always clear what stage of CKD is being discussed. Often the article you’re reading may be aimed at someone on dialysis rather than someone trying to prevent the need for it.  

Moreover, it is not just the stage that determines your particular needs, but many other factors as well. Working with a registered dietitian who is also a specialist in renal nutrition is one of the best ways for you to determine what your opportunities are for kidney health.

I’ve found that the most commonly misunderstood dietary restrictions are potassium, phosphorus, protein, and fluid needs. Let’s take a look at each one.

Potassium

Potassium is an important mineral in your body that is responsible for many functions. It helps regulate fluid and mineral balance, helps maintain normal blood pressure, and it may reduce the risk of recurrent kidney stones and bone loss as we age. It also conducts electricity throughout the body. This electricity keeps your muscles working normally.  Since your heart is a muscle, if your potassium level is too high or too low, it can be very serious.

It seems to me that many of my clients think they need to restrict potassium.  It is not always clear how they came to this conclusion. Did their own research lead them to believe that? Was it communicated to them by a healthcare practitioner? Or did a well-meaning friend or family member put the idea in their mind?

Not everyone with CKD needs a potassium restriction.

Why?

Because your heart needs a certain amount of potassium to function properly. If you automatically restrict your potassium intake just because you’ve been diagnosed with CKD, you may be getting ahead of yourself.

There are other reasons as well. Restricting the potassium in your diet unnecessarily can lead to inadequate fiber intake, inadequate vitamin and mineral intake, a higher net acid production, poor sodium excretion, and ultimately accelerate kidney function decline.  On the other hand, eating a diet high in fruits and vegetables (such as the Mediterranean Diet) has been shown to slow kidney disease progression.

Your doctor probably monitors your potassium level regularly by checking a comprehensive metabolic panel or a renal panel. Your potassium level is what determines whether you need a dietary potassium restriction. A normal potassium level is 3.5-5.0 mg/dl.   If your potassium level is greater than 5, you may need to restrict your potassium intake. But there are other factors involved in your blood potassium level that can be considered before you start restricting your dietary potassium intake.

You can read more about potassium here.

Phosphorus

People with CKD seem to be universally confused by potassium and phosphorus. When I worked in dialysis, I had patients who’d been on dialysis for years who did not know the difference between phosphorus and potassium in spite of monthly education.

Phosphorus is an essential mineral. It is a key component of bones, teeth, and cell membranes and plays a vital role in energy production, muscle function, and cell repair. In the body, phosphorus is mainly found in the form of phosphate.

Phosphorus works with calcium to build and maintain strong bones and teeth. It plays an important role in energy metabolism, it helps form DNA, RNA, and cell membranes, and it maintains the body’s pH balance.

Phosphorus occurs naturally in many foods, including dairy, meat, legumes, nuts and seeds, and whole grains.

It also occurs in processed foods in the form of phosphate additives.

Most people on dialysis need a phosphorus restriction because the kidneys are no longer filtering excess phosphorus out of the blood.  When that happens, phosphorus builds up and disrupts normal body processes.  

If you are in an earlier stage of CKD, excessive phosphorus intake can lead to poor outcomes.  However, naturally occurring phosphorus is not well-absorbed and many of the foods containing it have significant health benefits for people with CKD. On the other hand, phosphate additives are absorbed at about 100% and are typically found in foods with fewer health benefits. 

For these reasons, I typically teach my clients how to read labels for phosphate additives and avoid foods containing them. But I do not recommend they restrict naturally occurring phosphorus from whole grains, beans, nuts, and seeds. 

If you’ve been doing research on the internet and have found lists of foods to avoid that contain those foods, you now know why.  

Protein

Protein is a macronutrient that is essential for building, repairing, and maintaining tissues in the body.  It is essential to normal human functioning. 

Protein is another dietary component that can be confusing when it comes to CKD, and the reason is really quite simple compared with phosphorus and potassium.

You have CKD and are trying to preserve your kidney function. You have lower protein needs because of its impact on the kidneys. Excess protein taxes the kidneys.

People on dialysis have high protein needs due to the protein that is removed from the blood during dialysis. They have already lost their kidney function and are not trying to preserve it, so restricting its intake is not only unnecessary but also detrimental.

If you found a list or an article that is intended for people on dialysis, you may have seen the protein recommendations are higher than average.  If you are trying to preserve kidney function, your protein needs are lower than average. Following the wrong guidelines could be a life-altering mistake in this case.

Learn more about protein and CKD here.

Fluid

Finally, you may be confused about your fluid needs if you’re looking at the wrong list or article.  

People on dialysis generally need to restrict their fluid intake to avoid fluid overload. But people trying to preserve kidney function generally need to have higher fluid intake to preserve kidney function. This varies depending on your particular situation, but in general, adequate fluid intake is essential for preserving kidney function.

If you’ve found a list that says you should only be drinking 1 liter of fluid per day, you’ve got your hands on the wrong list. Please do not follow the guidance you find there because it is not intended for people seeking to preserve kidney health. 

Learn more about fluid needs for CKD here.

The Bottom Line

At the very least, please make sure when doing your internet searches that you’re looking at the right list for your stage of CKD.

But I’d like to invite you to end the confusion for good. I’ve developed a comprehensive 12 week 1:1 program that is designed to identify what I call your kidney health levers and help you focus on the changes that are necessary for you to preserve kidney function, and avoid focusing on those areas that you don’t need to focus on. I call it the Kidney Health Clarity Program. To learn more, you can click the link below.  If you’re looking for expert guidance on what to do to preserve your kidney (and overall) health, please explore this option and apply to work with me!

References

Wahl P, Wolf M. FGF23 in chronic kidney disease. Adv Exp Med Biol. 2012;728:107-25. doi: 10.1007/978-1-4614-0887-1_8. PMID: 22396166. https://pubmed.ncbi.nlm.nih.gov/22396166/

Noori N, Sims JJ, Kopple JD, Shah A, Colman S, Shinaberger CS, Bross R, Mehrotra R, Kovesdy CP, Kalantar-Zadeh K. Organic and inorganic dietary phosphorus and its management in chronic kidney disease. Iran J Kidney Dis. 2010 Apr;4(2):89-100. PMID: 20404416.

Bayán-Bravo A, Banegas JR, Donat-Vargas C, Sandoval-Insausti H, Gorostidi M, Rodríguez-Artalejo F, Guallar-Castillón P. The Mediterranean Diet Protects Renal Function in Older Adults: A Prospective Cohort Study. Nutrients. 2022 Jan 19;14(3):432. doi: 10.3390/nu14030432. PMID: 35276791; PMCID: PMC8839505. https://pubmed.ncbi.nlm.nih.gov/20404416/

KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update. Ikizler, T. Alp et al. American Journal of Kidney Diseases, Volume 76, Issue 3, S1 – S107 https://www.ajkd.org/article/S0272-6386(20)30726-5/fulltext