Potassium is a soft, silvery-white mineral found naturally in the earth, and it’s critically important to the function of certain processes in the human body. It’s also an electrolyte — which is a substance that’s crucial to the conduction of electrical signals throughout the body.
“It’s in that electrolyte ‘gang of three’ with sodium and chloride,” says Cathy Leman, a dietitian, personal trainer, nutrition therapist, speaker, writer and breast cancer survivor based in Chicago. “It’s integral and essential as a part of every cell,” and is required for cell growth and nerve signaling.
Potassium is part of many foods and it’s “very water-soluble, so it’s easily absorbed and readily usable,” Leman says.
What Does Potassium Do?
Potassium is “very important in generating muscle contractions and regulating heartbeat,” and it plays a big role in energy metabolism, Leman says. It helps the body build proteins from amino acids and metabolize carbohydrates for energy. Potassium helps your body convert glucose (sugar) into glycogen, which is then stored in the liver, so that you have fuel to walk, run or do whatever else you need to do.
“Potassium is also involved in a process called the sodium-potassium exchange that happens across cell membranes,” Leman says. “That’s what generates the electrical potential that aids all the nerve impulses in the body.” As such, “potassium is linked with nerves, heart rate and muscular contraction.”
In fact, every movement your body makes and any thoughts you have are made possible by potassium helping cells communicate with one another.
In particular, taking in adequate levels of potassium is critical to keeping your heart functioning properly. The heart is essentially just one large muscle, so adequate potassium levels are important for keeping the heart functioning properly.
Siera Holley, a registered dietitian nutritionist at the Ohio State University Wexner Medical Center in Columbus, adds that potassium helps maintain a regular heartbeat. “Both too little and too much potassium can cause an irregular heartbeat or arrhythmias.”
Potassium also has several other important functions, including:
— Helping cells maintain appropriate osmotic pressure, or keeping the right fluid balance to function optimally.
— Helping maintain pH balance in the body. Potassium is a basic element, meaning it’s alkaline in nature, which helps balance out excess acidity. Too much acidity can lead to cellular death, so again, staying within the right zone of pH is key to maintaining optional function.
— Helping offset sodium’s impact on blood pressure. “Studies examining the effect of potassium intake on blood pressure have reported improvements in participants’ systolic and diastolic blood pressure with increased potassium intake,” Holley notes. “Because high blood pressure is a risk factor for cardiovascular disease, potassium may also assist in the prevention of CVD.”
In essence, potassium helps the body maintain the delicate balance that makes life possible. “Those electrical impulses are so finely tuned, it balances on a very thin wire,” Leman says. “With that sodium-potassium exchange, it’s almost like a finely tuned dance. One misstep — and that misstep might be coming from diarrhea, vomiting or a medication that changes the level of potassium in the body — that changes everything.”
How Much Potassium Should I Consume Each Day?
The National Institutes of Health Office of Dietary Supplements reports that adults aged 19 and older should consume 4,700 milligrams of potassium daily. (For reference, a medium-sized banana contains about 400 mg of potassium.)
Breastfeeding women should seek 5,100 mg daily, while children under age 13 need less, ranging from 400 mg during their first six months up to 4,500 mg daily between the ages of 9 and 13.
Which Foods Are High in Potassium?
Bananas are often listed as the go-to food for people seeking to add potassium to their diet, but they’re not the only food that carries significant levels of this vital nutrient.
“The good thing about potassium is that it’s found in such a wide variety of foods,” Leman says.
Good Sources of Potassium
Whole foods such as fruits and vegetables offer the highest levels of potassium. Good sources include the following foods, with average amounts of potassium, as reported by the U.S. Department of Agriculture:
— Banana. One medium banana contains 422 mg of potassium.
— Oranges. One small orange contains about 175 mg.
— Grapefruit. Half a pink grapefruit contains about 165 mg.
— Melons, including cantaloupes (417 mg per 1 cup), honeydew (388 mg per 1 cup) and watermelon (170 mg per 1 cup).
— Apricots. 427 mg per cup.
— Kiwi. One whole kiwi fruit contains 215 mg of potassium.
— Dried fruits such as prunes, raisins and dates. A single prune contains 70 mg potassium. A small box (1.5 ounces) of raisins contains 322 mg of potassium. One Medjool date contains 170 mg of potassium.
— Avocado. One whole avocado contains 975 mg of potassium.
— Sweet potatoes. One sweet potato (about 5 inches long) contains about 440 mg of potassium.
— White potatoes. A large potato (about 3 to 4 inches in diameter) can contain more than 1,500 mg of potassium.
— Mushrooms. One cup of whole, white mushrooms contains more than 300 mg.
— Peas. A cup of green peas contains 354 mg of potassium.
— Zucchini and squash. One medium zucchini contains 512 mg and a cup of butternut squash has nearly 500 mg of potassium.
— Leafy greens, such as Swiss chard and spinach. One cup of cooked Swiss chard contains 960 mg of potassium, and one cup of cooked spinach contains about 840 mg of potassium.
— Pumpkins. One cup boiled and mashed contains 564 mg.
— Beets. A half-cup of sliced beets contains 260 mg.
— Broccoli. One cup of raw broccoli contains nearly 300 mg.
— Brussels sprouts. A half-cup of boiled contains 247 mg.
— Carrots. One cup of grated carrots contains 352 mg.
You can also find potassium in some fish, such as tuna, halibut and cod. Clams, meat and poultry also provide potassium. Beans and legumes, such as lima, pinto or kidney beans and lentils are also rich sources. Molasses, yogurt, cow’s milk, soy milk, pumpkin seeds, sunflower seeds and nuts are also good sources of potassium.
When grocery shopping, make note of the potassium levels in the items you buy, which are clearly marked on the labels. “Checking the daily value that is listed for potassium can be helpful,” Holley says. “A daily value of 20% or greater per serving indicates that a food is high in that nutrient.”
What Happens If I Don’t Get Enough Potassium?
Potassium is a Goldilocks mineral – having too little can be deadly, just as having too much, can also be fatal. Therefore, it’s very important to get the right balance. When you don’t have enough potassium in your diet, a condition called hypokalemia can arise. Hypokalemia can disrupt the delicate balance of electrical signaling and lead to noticeable symptoms.
Symptoms of hypokalemia include:
— Muscle weakness, which if not addressed can eventually turn to paralysis.
— Muscle twitching.
— Muscle cramping, especially at night.
— Abnormal or irregular heart rate, such as palpitations or atrial fibrillation.
— Mood changes and psychological symptoms including depression, psychosis or hallucinations have been linked to low potassium in extreme cases.
Holley notes that “the general United States population is not reaching the recommended daily amount of potassium each day due to a large intake of processed and packaged foods that tend to be low in the nutrient. Because of this, the 2020-2025 Dietary Guidelines for Americans identify potassium as a dietary component of public health concern in addition to calcium, vitamin D and dietary fiber.”
The National Institutes of Health also reports that most people in the United States are not getting the recommended amount of potassium from their diet. In particular, people with inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis, and people who have a rare eating disorder called pica — where they habitually or compulsively eat non-food items such as dirt or hair — tend to have trouble getting enough potassium.
Similarly, some medications change the way the body is able to regulate potassium levels, and you may end up excreting too much. For example, laxatives, blood pressure medications and diuretics — medications that flush excess fluid out of the body — can reduce your potassium levels and lead to deficiencies.
Because potassium is water-soluble, it leaves the body through fluids, so vomiting, diarrhea and excessive sweating, whether from intense exercise or hot weather, can all reduce your stores of the nutrient. Alcohol use and excessive caffeine intake can also deplete potassium.
Holley recommends adopting the DASH diet, which stands for dietary approaches to stop hypertension. This diet “provides a great framework for incorporating more potassium into your diet” because “it encourages a diet rich in fruits and vegetables, whole grains, lean animal and plant-based proteins.” The DASH diet also recommends limiting sodium, sugar and unhealthy fats. While its name indicates it is intended for those with high blood pressure, many people can benefit from adopting this eating plan regardless of hypertension concerns.
What Happens If I Have Too Much Potassium?
Before making any adjustments to your diet, Holley says it’s best to speak with your primary care provider or a registered dietitian. With potassium, it’s possible to take in too much. Abnormally high levels of potassium causes a condition called hyperkalemia.
Symptoms of hyperkalemia include:
— Weakness and fatigue.
— Numbness and tingling in the limbs and extremities.
— Nausea and vomiting.
— Chest pain, palpitations or irregular heartbeats.
Again, certain medications can trigger this unusual condition, such as:
— Potassium-sparing diuretics, these are sometimes used to treat high blood pressure.
— ACE inhibitors, which are also used to treat high blood pressure.
— Nonsteroidal anti-inflammatories, such as ibuprofen and naproxen sodium.
— Heparin, which is an anticoagulant, or blood thinner.
It is possible to overdose on potassium, but this is very unlikely to happen in a healthy person who simply eats a lot of potassium-rich foods because potassium is water-soluble. This means you’re more than likely to urinate out excess levels of potassium.
However, certain medications, such as potassium-sparing blood pressure medicine can elevate your risk of hyperkalemia.
Should I Take a Potassium Supplement?
“Unless a supplement is prescribed by your doctor, it’s best to get potassium from dietary sources,” Leman says. But for some individuals, a supplement might be helpful, and your doctor can help you find the right one for your situation.
Leman notes that these products tend to offer relatively low levels of potassium — by design. “The potassium dose is very low intentionally so you’d have to take a lot of them to overdose or overdo it to a toxic level.”
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Update 05/11/22: This story was published at an earlier date and has been updated with new information.