‘A low-potassium diet, recommended for kidney disease, can ruin health if done excessively’

It is well known that a low-sodium diet combined with a low-potassium diet is beneficial for kidney disease, leading many patients to follow an excessively low-potassium diet. However, this is not a wise way to manage kidney disease.

“Potassium should be adjusted selectively according to one's condition. In some cases, excessive restriction of potassium intake can actually worsen potassium levels, so it is important to consult with your primary care physician at least once,” said Professor Ahn Jung-nam of the Department of Nephrology at Hallym University Sacred Heart Hospital on the Korean Society of Nephrology's YouTube channel, “My Kidneys, My Health.”

For this reason, the first principle of a wise low-potassium diet is to check one’s potassium level and adjust the diet accordingly. It is also not advisable to completely eliminate all foods high in potassium.

“You should not completely eliminate all foods high in potassium. Similar to a low-sodium diet, you should limit foods and products that are slightly high in potassium and consume foods that are low in potassium more freely, adjusting the amount and frequency of consumption,” Professor Ahn said.

While most vegetables and fruits contain potassium, not all vegetables and fruits are high in potassium. Therefore, the recommended approach is to consume fruits with lower potassium content freely and limit those with higher potassium content.

Apples are known to have relatively low potassium content, while tomatoes, bananas, grapes, and watermelons have high potassium content. Therefore, it is advisable to consume tomatoes, bananas, grapes, and watermelons in moderation and enjoy fruits with lower potassium content more freely, Ahn explained.

There is another way to reduce potassium intake when eating vegetables and fruits. “The best way to reduce potassium intake is to peel the skin off fruits before eating them. If you swallow the seeds, be sure to spit them out. Dried fruits have higher potassium content, so it is recommended to eat fresh fruits instead of dried ones,” Ahn added.

Additionally, it is advisable not to eat too much fruit at once. Peeled fruits should be cut into small pieces and soaked in cold water to reduce potassium content. The same applies to vegetables. For vegetables like tomatoes, it is better to peel them before eating, and soaking them in water can also help with a low-potassium diet.

“When soaking vegetables in cold water, the higher the water temperature, the better, but soaking them in warm water reduces freshness, so it is best to use lukewarm water that is neither too hot nor too cold, soak the vegetables in plenty of water after cutting them into small pieces, and leave them for at least two hours to effectively remove potassium,” he continued.

The key here is the amount of water. “The more water you use and the longer you soak the vegetables, the better. However, it is important to set the amount and time based on freshness and consumption timing,” Professor Ahn noted. “Additionally, cutting the vegetables into smaller pieces before soaking is more effective. When not eating them raw, blanch them first, then drain the water before consuming to reduce potassium intake.”

Besides, consuming the leaves rather than the stems or roots of vegetables is beneficial for a low-potassium diet. Additionally, among patients with kidney disease, some focus on a low-sodium diet and consume large amounts of vegetables or fruits to reduce salt intake, which can instead expose them to high potassium and high blood sugar levels.

“Even if you reduce salt intake, you may end up consuming too much potassium through fruits and vegetables or raising your blood sugar levels with fruits,” Ahn emphasized. “Therefore, patients with high blood sugar and high potassium levels should consult their primary care physician and avoid excessively consuming vegetables or fruits simply by adjusting salt intake.”