Low Potassium Diet…Do you really need one?

Published on: 02/21/2024
If you have chronic kidney disease (CKD), you may be under the impression that you need to follow a low potassium diet. This may or may not be true. Read on for help in determining if you really do.

CKD occurs when your kidneys are damaged over time and are unable to function normally.  Kidneys have many functions, but one of them is to balance important minerals in the body.  One of those minerals is potassium. When the kidneys are not working as well as they should, the excess potassium in your blood that would normally be filtered out and exit your body through urine, can remain in your blood instead.  This can cause problems.

First, what is 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 (you’ve heard of electrolytes, right?).  This electricity keeps your muscles working normally.  Since your heart is a muscle, if your potassium level is too high or too low, you can imagine that it can be very serious.

But…not everyone with CKD needs a low potassium diet.

Why?

Because your body 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.

It’s true that if your blood potassium level is too high (hyperkalemia), you can experience heart palpitations, irregular heart beat, shortness of breath, chest pain, nausea and vomiting, or even a heart attack.

However, if your blood potassium level is too low (hypokalemia), you can also experience symptoms.  These include abnormal heart rhythms, muscle twitches, cramps, low blood pressure, and lightheadedness. 

Restricting your potassium unnecessarily can not only cause hypokalemia, it can contribute to constipation by limiting fiber intake, cause nutrient deficiencies by limiting your intake of fruits and vegetables, increase your risk for metabolic acidosis, and overall affect your quality of life and potential for kidney function decline.

Working with a dietitian like me who specializes in CKD can help you determine whether you need a potassium restriction and how to go about implementing one.

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.

What are the factors that affect serum potassium levels?

There are many things besides diet that affect your potassium level. These include medications, constipation, blood sugar, and some supplements.

Medications that can cause high potassium include: antibiotics, antifungals, and blood pressure medications (ACEs and ARBs). If you’re on any medications that may be contributing to hyperkalemia, discuss it with your doctor.

If you experience constipation, it may also be contributing to your hyperkalemia.  The intestines are partially responsible for removing excess potassium from your blood via the stool, but when your bowels don’t move as quickly as they should, it can result in potassium being reabsorbed from the stool into the blood. Restricting your potassium intake can actually result in further increasing your serum potassium by inducing more constipation!

There are many herbs and supplements that can contribute to hyperkalemia.  The National Kidney Foundation lists quite a few here. If you are using any of these and have been told to restrict your potassium intake, you should consider stopping your supplement(s) first. 

Elevated blood sugar can also cause your potassium level to be high. When glucose levels are high, cells may not take up as much potassium from the bloodstream as they normally would in response to insulin. This can lead to higher levels of potassium remaining in the bloodstream. So if you have diabetes, controlling your blood sugar can also help control your potassium level.

Chances are that if you really and truly need a potassium restriction you are in late stage CKD (stage 4 or 5).  

There is no RDA for potassium, but organizations around the world recommend 3500-4700 mg/d for most people. For my clients who need a potassium restriction, I usually recommend keeping their dietary potassium intake less than 2000 mg per day or less than 700 mg per meal. For a list of higher potassium and lower potassium foods, go here.

My Chronic Kidney Disease course is a great place to start if you’re looking to discover more about diet and CKD. You’ll learn about potassium, and many other components of your diet that can affect kidney health.

Click the button below to learn more about my online CKD course.

References:

Chronic Kidney Disease (CKD). National Kidney Foundation.  https://www.kidney.org/atoz/content/about-chronic-kidney-disease

Herbal Supplements and Kidney Disease. National Kidney Foundation.  https://www.kidney.org/atoz/content/herbalsupp

Keiichi, S. (2019, November 13) Constipation in CKD. National Library of Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7000799/

How Much Potassium do you need per Day? Healthline. https://www.healthline.com/nutrition/how-much-potassium-per-day

https://nap.nationalacademies.org/resource/25353/030519DRISodiumPotassium.pdf

Kemmann, S. (2021, March 2) What is Potassium? 

Https://Eatright.org/health/essential-nutients/minerals/what-is-potassium

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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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