Is Potassium Good or Bad in Kidney Disease: The Potassium Controversy

Feeling frustrated about managing the complexities of a new diet in kidney disease? Wondering how much you should be limiting potassium? Our clinic can help you decide how much potassium you need.

Many studies are suggesting potassium may not be as big of a concern as originally thought. Guidelines suggest that people often do not need to to limit potassium until their kidneys are working at less than 30% and/or blood levels are high. However, everyone is different - and we can help assess how important potassium restriction is for your case.

When someone does need to eat less potassium, it’s usually better to cut out snacks and drinks that are low in nutrition but high in potassium—things like potato chips, fruit juices, and other processed foods—rather than healthy fruits and vegetables (2022 study, 2008 study).

We try to tailor potassium restrictions because, for most people (including those with mild kidney problems), eating potassium-rich foods is actually linked to better health. Studies show that people who eat more potassium have a lower chance of developing kidney disease and their kidney function declines more slowly if they already have kidney issues. Other benefits of getting enough potassium include lower blood pressure (2001), a lower risk of stroke, and stronger bones. In one large study, people who closely followed potassium-packed diets, like the Mediterranean diet or the DASH diet, actually had a much smaller risk of their kidney disease getting worse and were about 25–30% less likely to die from any cause during the study.

Key Research:

A 2024 study on those with kidney disease found:

• Patients with the lowest estimated potassium intake had a 24% higher risk of kidney disease progression compared to those with the highest potassium intake.

• Overall potassium restriction for patients with CKD may deprive them of the beneficial effects associated with a healthy diet in potassium and other nutrients.

A 2021 study on those with kidney disease found:

• A trend towards lower blood pressure with higher potassium intake

Another 2021 study on patients with kidney disease undergoing dialysis found:

• Those with the lowest potassium intake had a shorter longevity (survival) compared to those with the highest potassium intake

A 2019 study on healthy potassium-rich diets in patients without kidney disease found:

• 30% lower risk of developing kidney disease

• 23% lower risk of developing protein in the urine (a sign kidneys are leaking and injured)

• 30% trend towards slower kidney function decline

Another 2019 study on healthy potassium-rich diets in patients without kidney disease found:

• 14% reduced risk of kidney disease

• Preserved kidney function

However, this research also found that if the diet is both high in potassium and overall unhealthy, then this leads to increased risk of kidney disease. This reinforces that limiting unhealthy potassium sources is helpful.

Why Does the Research Seem Conflicting?

The research is somewhat conflicting, but more so it is very context-specific. For example, in early kidney disease the kidneys can usually easily handle potassium, whereas in late kidney disease it becomes more difficult for the kidneys to filter it out - so it can be more of an issue at this point. Potassium is also good for certain health conditions whereas it can be bad for others. There is no blanket statement that applies to everyone with kidney disease. Different situations can affect how the body handles potassium and responds to potassium.

Does Potassium Restriction Affect Kidneys?

So far the research we have is limited on the impact on kidney function in those with established kidney disease. Many of the high-potassium foods have other compounds that are healthy for the kidneys. In fact, a 2020 study on those with kidney disease actually found a 14% trend towards increased progression of kidney disease in those with low potassium intake. The 2024 study above as well found that those with kidney disease who had the lowest estimated potassium intake had a 24% higher risk of kidney disease progression compared to those with the highest potassium intake.

Does Potassium Restriction Reduce Potassium?

Ironically, the 2020 study above also found that restricting dietary potassium had very little impact on a person’s potassium levels. Those on the lower potassium diets had a -0.22 mEq/L reduction in potassium. In other words, potassium levels in the body are often related to other factors rather than diet.

Does Potassium Restriction Improve Health

All this said, for those with higher levels of potassium, some restriction (eg. of generally unhealthy foods) may be helpful as the 2020 study also found a benefit to overall health as measured by longevity (surviving participants). The authors concluded: “Very-low-quality evidence supports consensus that dietary potassium restriction reduces potassium in normokalemia and is associated with a reduced risk of death in those with CKD. High-quality randomized controlled trials are needed.”.

Reducing Food Potassium

Many foods that are considered high potassium are actually quite low in potassium if they are prepared in certain ways. For example, studies have shown that by following specific boiling instructions up to 95% of the potassium can be removed from certain foods. This means certain healthy high potassium foods can be integrated into the diet. Our clinic can walk you through the best ways of reducing potassium in foods.

How Much Restriction is Necessary?

It depends on your kidney function and potassium levels. Our clinic can help assess the level of restriction needed - but often for many patients no restriction is necessary and for others many healthy foods can still be consumed if processed properly.

How Much Potassium Is Okay?

For those who need to restrict, many guidelines suggest around 3 grams per day of potassium.

Potassium Restriction & Food-Anxiety

It is not uncommon for those with kidney disease to feel anxious and worried about what they are eating. Too much anxiety around food can lead to diets becoming overly restrictive and limited in nutrition. Severely restricting foods can make meal planning frustrating and overwhelming – further adding to anxiety. Our clinic can help you navigate the complexities of food in the context of kidney health. We recommend a balanced approach and we look at the patient as a whole, all aspects of your health, rather than just a number on a lab test.

Conclusion

With regards to kidney health, potassium doesn’t seem to affect kidney function one way or another – and one study even found a trend towards slight improvement in kidney function with higher potassium intake. However, some restrictions may be necessary in certain cases as some research shows it may provide benefits to overall health and longevity. Our clinic recommends a balanced approach that includes lots of healthy foods and makes planning meals manageable. If you’d like to take a more preventative approach to your potassium and keep it low, we can guide you on removing unhealthy potassium sources, reducing additives and how to process foods properly to remove most of this mineral. 

Overly restrictive diets can be frustrating