Most people don’t get enough potassium. Only 20-40% of Americans hit the National Academy of Medicine adequate intake for potassium — 3.4 grams per day for men, and 2.6 grams per day for women. — and the evidence for higher intakes between 3.5–5 grams per day seems promising.
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 levels are super depleted, an electrolyte imbalance can present 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
Our bodies need potassium for a ton of different reasons. 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 that the answer for healthy people is no. Not only have low-sodium diets been 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:
- Dietary potassium deficiency
- 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 60–80% of Americans not hitting the adequate intake of 3.4 grams per day (for men) and 2.6 grams per day (for women). This figure was set to minimize the risk of high blood pressure and kidney stone formation, and I think it’s a decent starting place.
However, the evidence suggest that getting between 3.5 and 5 grams of potassium each day could lead to greater benefits than those of mere adequacy.
It’s no shocker we’re low on potassium. The Standard American Diet (SAD) is largely devoid of potassium-rich fruits and vegetables. Instead, it’s high in health-deranging pseudo foods like refined sugar and industrial seed oils. There just isn’t much potassium in cola, Milano cookies, or Goldfish.
#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 leave the blood and return to tissues, resulting in hypokalemia.
Many illnesses can also cause hypokalemia since potassium is lost directly through stool 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. Not to mention, if 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 potassium deficiency most Americans experience? We can do something about that.
For most people, however, hitting at least 3.5 grams of potassium per day isn’t exactly 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
Clearing 3.5 grams of potassium 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. Many folks could benefit from about a gram of supplemental potassium per day. Depending on your diet, you may need to supplement more or less than this.
How can you dial it in? Easy. Just download any diet tracking app, log your meals for a few days to see how much potassium is coming in, and adjust your supplement routine to hit your larger target. That’s how you assess potassium status. Don’t guess by symptoms alone — they can be subtle and mimic many other conditions and deficiencies. The dietary analysis, on the other hand, won’t deceive you.
Once you’re cruising along at 3.5–5 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. You may even find that some of these problems improve at higher potassium intakes. That would be a nice result, wouldn’t it?
