What are the symptoms of low potassium? (And 10 best sources of potassium)

Most people don’t get enough potassium. Only 3% of Americans hit the Institute of Medicine target of 4.7 grams per day.

The symptoms of low potassium can be subtle. It’s difficult, for example, to detect the mild elevation in blood pressure that can result from potassium deficiency.

Potassium also supports bone health, energy production, and muscular function. Because of this, chronically inadequate potassium can manifest as brittle bones, fatigue, and muscle cramps.

When potassium gets super low, the deficiency shows up in the blood. This state of low serum potassium (called hypokalemia) is serious stuff that often requires medical treatment.

The key words here are “super low”. Waiting until you actually become clinically hypokalemic before you begin to increase potassium intake is like waiting until you’re bankrupt before you make a monthly budget. It’s foolish and dangerous.

Hypokalemia is usually the result of other medical conditions—illness or kidney disease, for example. But all things equal, a low potassium diet increases the risk of developing hypokalemia.

Today I want to talk about low potassium in the diet and in the blood. Then I’ll share simple strategies for correcting it.

Before I do that, though, I want to cover some background on this crucial electrolyte.

The Importance of Potassium

Why do we need the mineral called potassium? Where do I start...

Potassium:

  • Serves as an electrolyte, a charged mineral that facilitates cellular communication.
  • Helps you maintain healthy blood pressure by balancing the effects of sodium.
  • Increases calcium absorption in the kidneys to decrease kidney stone risk.
  • Supports insulin secretion to promote healthy blood sugar levels.
  • Supports bone density by counteracting an acidic diet.
  • Structures potassium channels that regulate heartbeat, nervous system communication, and much more in all living systems.
  • Supports fluid balance (optimal water levels) in your body

I could go on, but you get the idea.

The blood pressure benefit is the most famous. Across the literature, higher consumption of potassium is associated with lower systolic and diastolic blood pressure.

More convincingly, a 2017 meta-analysis of randomized controlled trials found that long-term potassium supplementation lowered blood pressure in those with hypertension. This effect was strongest in individuals with low dietary intakes of potassium.

Potassium lowers blood pressure, in part, by increasing sodium excretion. Does this mean you should restrict sodium to amplify this effect?

I’m confident the answer is no. Not only are low sodium diets correlated with higher blood pressure, but a serious sodium deficiency can also make you pee out potassium faster. Then you’re really up the creek.

Speaking of low potassium, let’s talk about what that means.

What Does Low Potassium Mean?

When people talk about low potassium, they could be talking about one of two things:

  1. Dietary potassium deficiency
  2. Hypokalemia

Let’s review these separately.

#1: Dietary potassium deficiency

Dietary potassium deficiency means you aren’t getting enough potassium from diet and supplements to promote optimal health. It’s a widespread problem, with 97% of Americans not hitting the Institute of Medicine target of 4.7 grams per day, originally set to minimize the risk of high blood pressure and kidney stone formation.

It’s no shocker we’re low on potassium. The Standard American Diet (SAD) is largely devoid of potassium-rich fruits and vegetables.

Instead the SAD is high in health-deranging pseudo foods like refined sugar and industrial seed oils. There just ain’t much potassium in cola, Milano cookies, or Goldfish.

There is, however, plenty of sodium. Because of this, confused pundits blame salt for the American metabolic crisis.

But is it the sodium? Or is it the lack of potassium, the lack of plants, the high sugar intake, and the consumption of oxidized vegetable oils?

My money is on door number two. If you want to learn more, read Robb’s deep dive on sodium.

#2: Hypokalemia

Hypokalemia is the medical term for low serum potassium. It typically warrants medical attention.

A low potassium diet can contribute to hypokalemia, but it’s not the proximate cause. Hypokalemia is rare in those with healthy kidneys. It’s usually caused by a medical condition.

Refeeding syndrome is one of these conditions. During periods of extreme nutrient deprivation (from alcoholism, extended fasting, chronic calorie restriction, or eating disorders), the body shuttles potassium from tissues into the blood to support normal functions. When the malnourished person eventually refeeds, the resulting insulin spike causes potassium to return to tissues.

Out of the blood, into the tissues. This can cause hypokalemia.

Many illnesses can cause hypokalemia since potassium is lost directly through feces (read: diarrhea) and vomit. Vomiting also depletes stomach acid, leading to a state of alkalosis. To normalize PH, your body excretes more potassium (which is alkaline) through urine, further depleting potassium levels.

Also, when you can’t keep food down, you won’t be consuming much potassium. This exacerbates hypokalemia.

Other risk factors for hypokalemia include:

  • Using certain diuretics and laxatives.
  • Having inflammatory bowel disease (IBD), which decreases potassium absorption through the gut.
  • Having a disorder called pica in which the patient will eat almost anything, including dirt, clay (which binds to potassium), nails, screws, and feathers.

During normal life, most potassium losses occur through bowel movements and urination. Very little potassium is lost through sweat. As a rule, these normal losses won’t provoke hypokalemia.

Testing Potassium Status

Hypokalemia will show up on a blood electrolyte panel. Dietary potassium insufficiency will not.

Most people don’t realize this, but the results from a potassium panel have little to do with consuming enough potassium for healthy blood pressure, fluid balance, kidney stone risk, etc.

Rather, the results are used to identify things like kidney and heart failure. For instance, if potassium levels are very high (hyperkalemia) it may indicate poor kidney function, suggesting an inability to excrete potassium through urine.

If potassium levels are very low (hypokalemia), it’s usually due to severe potassium losses in vomit or diarrhea.

And if potassium levels come back normal, it doesn’t mean you're getting enough potassium through diet. It merely suggests that your kidneys and heart are functioning normally. Keep this in mind next time you get bloodwork.

Low Potassium Symptoms

The symptoms of low potassium depend on the magnitude of potassium inadequacy. We’ll start with the signs and symptoms of a dietary deficiency.

Symptoms of Dietary Potassium Deficiency

If you’re not getting enough dietary potassium, the consequences aren’t always obvious. Mild elevations in blood pressure, impairments in insulin function, suboptimal bone density, and increased risk of kidney stones are easy to miss if you aren’t closely monitoring bloodwork and other biomarkers.

Potassium deficiency (considered mild hypokalemia) may also manifest as:

  • Muscle cramps
  • Fatigue
  • Constipation
  • Muscle weakness
  • Malaise

As potassium levels drop further, we enter the realm of true hypokalemia.

Symptoms of Hypokalemia

The following symptoms may indicate moderate to severe hypokalemia:

  • Cardiac arrhythmias
  • Slower heart rate
  • Polyuria (a large volume of dilute urine)
  • Brain damage
  • Glucose intolerance
  • Muscle paralysis

Potassium is crucial for muscle function, including the function of the heart. In cases of severe hypokalemia, these heart complications can be fatal.

As I said, people with healthy kidneys are at low risk for hypokalemia. But in the case of kidney disease, diarrhea, vomiting, or other condition, suspected hypokalemia should be treated in a medical setting.

How to Correct Low Potassium

I won’t talk about correcting moderate to severe hypokalemia today. That should be treated in a medical setting with oral or intravenous potassium under the watchful eye of a clinical care team.

But the everyday low potassium suffered by most Americans? We can do something about that. And when you optimize your potassium status, you’ll have a larger buffer to prevent more serious hypokalemia.

For most people, hitting 4.7 grams per day isn’t easy. It requires a concerted effort to eat electrolyte-rich foods.

Best Sources of Potassium

Here are some examples of foods high in potassium:

  • Salmon (624 milligrams per 6 ounce filet)
  • Lean beef (572 milligrams per 6 ounce filet)
  • Pork chops (584 milligrams per 6 ounces)
  • Chicken breast (440 milligrams per breast)
  • Avocado (690 milligrams per avocado)
  • Banana (422 milligrams per banana)
  • Dried apricots (2,202 milligrams per cup)
  • Cantaloupe (428 milligrams per cup)
  • Spinach (271 milligrams per cup)
  • Cooked lentils (731 milligrams per cup)
  • Asparagus (271 milligrams per cup)
  • Tomato (292 milligrams per tomato)

Optimizing Potassium Status

Some quick mental math reveals that clearing 4 grams will be difficult, even on a whole foods diet. And it gets even harder on low-carb or keto diets that restrict fruits and starchy vegetables.

That’s why I recommend folks take about a gram of supplemental potassium per day. This recommendation is based on a comprehensive analysis of folks in the Ketogains community.

We found that these folks—folks on real-food low-carb diets—tended to be very low on sodium, moderately low on potassium, and slightly skinny on magnesium. That’s why LMNT has 1000 mg sodium, 200 mg potassium, and 60 mg magnesium per stick. It’s the ratio that people need.

Depending on your diet, you may need more (or less) than 1 gram of potassium per day. Figuring this out is easy. Just download an app like Cronometer, log your meals for a few days, and see how much potassium is coming in.

That’s how you assess potassium status. Don’t do it by symptoms alone.

The symptoms can be subtle and mimic many other conditions and deficiencies. But the dietary analysis won’t lie.

And once you’re cruising along at 4 to 5 grams of potassium per day, you’ll be able to rule out low potassium as a potential cause of muscle cramps, high blood pressure, high blood glucose, fatigue, constipation, kidney stones, and any other problems that may be affecting you.

Or you might find that some of these problems improve at higher potassium intakes. That would be a nice result, wouldn’t it?