Every so often, a piece of outdated nutrition advice hangs on long after the science has moved on. And sometimes, it doesn’t just linger, it gets repeated so often that it becomes common knowledge, even when it’s wrong.
The potassium myth is one of those.
Last week, I wrote about how people with fatty liver are often given almost no guidance beyond a prescription. I didn’t expect to run into another issue so quickly, this time, not missing advice, but the wrong advice.
I used to think the potassium myth stuck around because we didn’t have enough data to challenge it. But we do. We have plenty of it.
And yet, just this week, two different people told me they were instructed to cut out bananas, potatoes, beans, and greens because their potassium was high.
I rolled my eyes. Again.
Because this isn’t just outdated. It’s harmful. And honestly… doesn’t anyone read the research anymore?
We can’t keep pretending we don’t know better. Because we do.
What High Potassium Actually Means
Let’s start with the big truth:
A high potassium result on a blood test is almost never caused by eating whole plant foods.
Your body handles potassium from real food slowly and safely because it comes packaged with fiber and water. That combination changes how potassium is absorbed, how quickly it enters the bloodstream, and how efficiently the body can regulate it.
So if your potassium level comes back high, here are the real reasons that usually explain it — and none of them involve bananas.
1. Medications
Some of the most commonly prescribed blood pressure medications raise potassium. These include:
- ACE inhibitors
- ARBs
- Spironolactone
These medications are effective and widely used — and raising potassium is a known, expected side effect. This is not a food issue. It’s a medication mechanism.
2. Dehydration
When you’re dried out, everything in your blood looks more concentrated — sodium, glucose, and yes, potassium.
This is especially common after:
- illness
- vomiting
- diarrhea
- long periods without drinking
- heavy sweating
Rehydration alone often brings potassium back into range.
3. The Blood Draw Itself
This one surprises people.
A high potassium result can happen because of the sample, not the person.
If:
- the tourniquet is too tight
- the arm is squeezed
- the blood sits too long before processing
…potassium leaks out of the cells and into the tube.
Her blood isn’t high.The sample is.
This is called pseudohyperkalemia, and it’s incredibly common.
4. Kidney Function
Your kidneys are the main regulators of potassium. If they’re not filtering well — maybe because of dehydration, diabetes, or other conditions — potassium can build up in the blood.
Even then, whole plant foods are almost never the cause. The kidneys struggle with supplements and additives, not potatoes.
5. Salt Substitutes and Additives
This is the one that actually matters.
Potassium chloride is used in:
- “low‑salt” salt substitutes
- electrolyte powders
- supplements
- processed foods
These can spike potassium quickly because they deliver potassium in a concentrated, fast‑absorbing form.
Whole foods don’t do that.
The Part No One Talks About: Fiber
Here’s the part that really gets me — and the part almost no one explains:
When someone doesn’t eat enough fiber, the body loses one of its main ways to get rid of extra potassium.
Fiber helps carry potassium out through the gut. So when people are told to avoid beans, greens, potatoes, and fruit, they’re being told to avoid the very foods that help the body regulate potassium.
Withholding the plants that nourish — and without them, create disease — is not caution.
It’s doing harm.
So Why Does This Myth Stick Around?
This myth survives because it’s simple and it’s been repeated for decades. It feels intuitive, even though it isn’t. And it’s far easier to blame a piece of fruit than to look at the real causes: medications, dehydration, kidney function, or a sloppy blood draw. But the evidence is clear, and it’s time the advice caught up.
What You Should Actually Do If Your Potassium Is High
Here’s the part where I stay in my lane:
I don’t diagnose, and I don’t give personalized medical instructions.
But I can tell you what the research shows and what clinicians typically evaluate:
- medications
- hydration status
- kidney function
- recent illness
- salt substitutes
- supplements
- lab technique
Food potassium from whole plants is almost never the culprit.
If your potassium is high, talk with your healthcare provider. Ask questions. Bring this information with you. You deserve accurate, up‑to‑date guidance.
The Bottom Line
Whole plant foods do not usually cause high potassium in the blood. And that old “avoid bananas and potatoes” advice?
It’s gotta go.
Your body thrives on plants. Your kidneys know how to handle potassium from real food. And your health depends on replacing outdated myths with real science.
If you’ve been told to avoid whole plant foods because of potassium, it’s time for a better conversation.
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