What causes hypokalemia? (Plus 15 potassium-rich foods)

From the desk of
Robb Wolf
ScienceWhat causes hypokalemia? (Plus 15 potassium-rich foods)

If you’re low on potassium, your body will notice. Mild potassium deficiency, for instance, can cause elevated blood pressure, bone density loss, and fatigue.

If you lose too much potassium, you enter the hell that is hypokalemia. Then you’re looking at the possibility of brain damage, muscle paralysis, and possibly fatal heart complications.

Hypokalemia is the medical term for low serum potassium, which is a fancy way of saying you need more potassium in your blood. And low-potassium diets, which lead to potassium deficiency, are seldom the sole cause.

That’s because your body has systems in place that will adjust to mitigate falling serum potassium levels, at least to a certain degree. Serum electrolytes are too vital to let go. But we have to get the potassium from somewhere, so a low-potassium diet is not without its share of consequences—and they are all too common.

It’s not helping that only 20–40% of Americans hit the adequate intake set by the National Academy of Medicine (NAM): 3.4 grams per day for men and 2.6 grams per day for women. And “adequate” intakes are just that… adequate. The evidence suggests that intakes between 3.5–5 grams per day may be more optimal.

Why are people so deficient in potassium? Because the Standard American Diet is notoriously devoid of fruits, vegetables, lean beef, seafood, and other potassium-rich foods. And so we have widespread potassium inadequacy. But since the signs of potassium inadequacy can often remain undetected through symptoms alone, most people don’t realize it’s a problem.

Hypokalemia symptoms, however, aren’t usually subtle. Now that we’ve clarified the difference, I’ll talk about hypokalemia, compare it to potassium deficiency, and lastly give tips for keeping your potassium intake dialed in.

What Is Hypokalemia?

Hypokalemia is a state of low serum potassium. Depending on the level of potassium in the blood, it can range from mild to severe.

Mild hypokalemia shows up as constipation, fatigue, muscle weakness, low energy, and muscle cramps. These are frustrating symptoms, but they’re not life-threatening.

Moderate to severe hypokalemia, on the other hand, presents with symptoms like:

  • Slower heart rate
  • Cardiac arrhythmias
  • Brain damage
  • Problems regulating glucose
  • Polyuria (a large amount of dilute urine)
  • Muscle paralysis

Potassium is crucial for muscle function, and hypokalemia derails the most valuable muscle in your body: the heart. These heart disturbances can be fatal.

As you might imagine, moderate to severe hypokalemia always requires medical treatment. Typically this means giving supplemental potassium through IV or oral routes. (Fun fact: liquid forms of potassium chloride have been shown to be better absorbed than tablet forms).

What Causes Hypokalemia?

Hypokalemia typically results from excessive potassium losses through urine, stool, or vomit. Those are the three main doors through which potassium exits the body.

A large proportion of hospitalized patients (about 21%) suffer from hypokalemia, mostly due to diuretic medications that increase urinary potassium loss. Laxative medications can also increase hypokalemia risk by increasing fecal potassium loss.

Any illness that causes diarrhea or vomiting will also deplete potassium levels. When treating cholera, for instance, doctors use salt, water and fluids to replace what’s lost through stool.

You also lose potassium directly through vomit, and vomiting stomach acid additionally lowers potassium by putting the body into a state of alkalosis. To normalize PH, your body excretes more potassium (an alkaline mineral).

Then there’s refeeding syndrome. In cases of severe nutrient deprivation due to extended fasting, alcoholism, or eating disorders, the potassium-starved body pulls potassium from the tissues and into the serum to fulfill basic functions.

When the person refeeds, a spike in the hormone insulin makes serum potassium rush back to the tissues. But it rushes too fast, and serum levels drop precipitously. Hello, hypokalemia.

One more thing. Hypokalemia is rare in people with healthy kidneys. That’s because the kidneys do a nice job regulating serum potassium levels, even when folks don’t get enough dietary potassium. Still, the VAST majority of people don’t get sufficient potassium, so their kidneys are perpetually in a state of harvesting/retaining more.

Groups At Risk for Hypokalemia

Compared to the general population, the following groups are more likely to suffer heavy potassium losses:

People with IBD

Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis increase potassium secretion in the gut. Combined with diarrhea, it’s a recipe for hypokalemia.

People taking certain medications

Those on diuretic, laxative, or a variety of other drugs will lose considerable potassium through feces and urine. Medical supervision is necessary to monitor potassium levels.

People with pica

People with a disorder called pica will eat nearly anything: dirt, clay, nails, feathers, tax returns, etc. Clay and dirt, unfortunately, can bind to potassium and carry it out through stool.

Hypokalemia vs Potassium Deficiency

Hypokalemia is a severe form of potassium deficiency that shows up in the blood. It’s rare in healthy people. But mild to moderate potassium deficiency isn’t rare. Most people eat potassium-poor diets, and this leads to bad consequences with blood pressure, bone density, and kidney stones.

Potassium inadequacy of this sort won’t show up in the blood. Your body knows that potassium is too important to let serum levels fall.

When you don’t get enough potassium, a few things happen:

  1. You excrete less potassium and less sodium through urine
  2. You excrete more calcium through urine
  3. Your body becomes moderately more acidic

These happenings help explain the insidious consequences of potassium deficiency:

#1: Sodium, potassium, and high blood pressure

Healthy blood pressure depends upon a healthy balance between sodium and potassium. An example will help illustrate.

Bob eats a typical modern diet. It’s high in sugar, high in salt, and low in potassium-rich foods such as lean beef, poultry, fish, milk, yogurt, fruits, and vegetables.

Bob is among the 97% of Americans who don’t consume enough potassium. As a result, Bob’s kidneys get the message (sent by hormones like antidiuretic hormone and aldosterone) to hold onto potassium like a starving bobcat on a leg of lamb.

This message, unfortunately, also increases sodium retention. Why is that unfortunate? Because a high sodium diet without adequate potassium increases Bob’s risk of developing high blood pressure.

It also doesn’t help that Bob is obese from his high-sugar, hypercaloric diet. Obesity is a well-documented risk factor for high blood pressure, and both are risk factors for heart disease.

The problem isn’t that Bob eats too much salt. (Low sodium diets have dangers of their own). The problem is that he isn’t getting enough potassium to balance it out.

#2: Potassium and kidney stones

Low potassium intakes also increase urinary calcium excretion. More calcium in the urine equates to a higher risk of calcium oxalate or calcium phosphate stones.

Looking at population data, higher potassium intakes appear to protect against kidney stones. There’s also at least one clinical trial showing that potassium supplements reduce kidney stone formation vs placebo.

#3: Potassium and bone density

Observational studies have shown higher potassium intakes to correlate with better bone density. A few trials also suggest potassium supplements can improve markers of bone health.

Researchers believe potassium works by decreasing acidic conditions that degrade bone. Another potential mechanism is that proper potassium status decreases calcium losses through urine.

How To Measure Potassium Status

To test for hypokalemia (low serum potassium) or hyperkalemia (high serum potassium), you need only a blood test. If it shows either of these conditions, seek medical attention. But if your heart and kidneys work properly—and you’re not ill or medicated—you probably won’t be hypokalemic.

That doesn’t mean, however, that you’re getting enough potassium. Regular old potassium deficiency won’t show up on a blood test.

I feel like I’m beating a dead horse, but there’s massive confusion on this point, so I need to keep hammering away. If your potassium test comes back normal, it doesn’t mean your potassium intake is sufficient.

The real way to know whether you’re potassium sufficient is through a dietary analysis and self-experimentation. Simply log your meals in an app like Cronometer and see how much potassium you consume every day. Based on the evidence, shooting for about 3.5–5 grams per day is likely to benefit most people.

If you’re low, the first step is to increase your intake of potassium-rich foods.

15 Potassium-Rich Foods

While they represent a “your mileage may vary” outcome for an individual’s macros, here’s a list of 15 potassium-rich foods to bump up your potassium status:

  1. Cooked lentils (731 milligrams per cup)
  2. Avocado (690 milligrams per avocado)
  3. Salmon (624 milligrams per 6 ounce filet)
  4. Potato (610 milligrams per medium potato)
  5. Cantaloupe (428 milligrams per cup)
  6. Banana (422 milligrams per banana)
  7. Milk 1% (366 milligrams per cup)
  8. Chicken breast (332 milligrams per 3 ounces)
  9. Beef, top sirloin (313 milligrams per 3 ounces)
  10. Tomato (292 milligrams per tomato)
  11. Spinach (271 milligrams per cup)
  12. Asparagus (271 milligrams per cup)
  13. Greek yogurt (240 milligrams per 6 ounces)
  14. Broccoli (229 milligrams per ½ cup)
  15. Cashews (187 milligrams per ounce)

Ensuring You Get Enough Potassium

As you can see, a diet rich in meat, vegetables, fruits, and nuts is essential for achieving your potassium target of 3.5–5 grams per day. But even on a whole foods diet, many people still fall short—especially during periods of calorie restriction.

That’s where supplemental potassium comes in. You can do this with potassium chloride powder or an electrolyte drink mix such as LMNT, which contains 200 mg of potassium chloride per stick pack to help folks meet these needs while providing balanced doses of the other electrolytes most folks need more of: sodium and magnesium.

Optimizing potassium status won’t prevent hypokalemia, but it will reduce the risk. Plus it has long-term benefits for your heart, kidneys, and bones. So get your potassium handled. A little extra effort today will pay off big time down the road.

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