If you were paying attention back in high school chemistry class, you might recall that potassium is the 19th element on the periodic table, represented by the letter K. Why not a P? Well, P was already taken, referring to element 15, phosphorous, and the K refers to the Latin name for potash, kalium. (Potash is a potassium-heavy compound that’s been used in bleaching textiles for eons.) No matter what it’s called, potassium is a soft, silvery-white mineral that’s critically important to the function of certain processes in the human body.
In this potassium primer, we’ll cover a range of health questions about this important mineral, including:
— What is potassium?
— What does potassium do?
— How much potassium should I consume each day?
— What happens if I don’t get enough potassium?
— What happens if I have too much potassium?
— Which foods are high in potassium?
— Should I take a potassium supplement?
[See: 9 Foods Packed With Potassium.]
What Is Potassium?
“Potassium is a mineral naturally found in the earth. It’s also what we call an electrolyte,” says Dr. Alyson Pidich, medical director of The Ash Center in New York City. Because potassium ions carry a positive charge, they’re integral to the conduction of electrical signals throughout the body.
As an electrolyte, “it’s in that electrolyte ‘gang of three’ with sodium and chloride,” says Cathy Lehman, a registered dietitian nutritionist, personal trainer and founder of Dam. Mad. About Breast Cancer, a nutritional resource for the breast cancer community. “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 of the foods we eat such a bananas, leafy greens and beans that’s “absorbed through the small intestine. It’s very water soluble, so it’s easily absorbed and readily usable,” Lehman says.
What Does Potassium Do?
Potassium is “very important in generating muscle contractions and regulating heart beat,” and it plays a big role in energy metabolism, Lehman 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,” Lehman 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.”
Pidich explains how important this synaptic signaling is: “Anytime you have a thought, potassium is carrying that thought through your brain. Anytime you want to move a muscle or move around, the thought has to come from your brain through your nerves to your muscles. And it’s potassium that carries that charge or that thought process all the way through to the muscles. When that charge gets to the muscle, then it’s potassium that helps move the muscle to create the contraction,” she says. “Potassium is literally embedded in that entire process in the body.”
Lehman says potassium also maintains appropriate osmotic pressure in the cells, meaning they can keep the right fluid balance to function optimally. As a basic element, meaning it’s alkaline in nature, potassium can help maintain the appropriate pH level in the body. It’s also implicated in the release of insulin by the pancreas, so it’s involved in a lot of different processes, all of which are important for maintaining optimal function of the whole organism. The U.S. National Library of Medicine reports that “a diet rich in potassium helps to offset some of sodium’s harmful effects on blood pressure.” But because the kidneys are involved with regulating the body’s levels of potassium, impaired kidney function — the kind triggered by kidney disease — can negatively impact potassium levels.
And particularly for the heart, not having the right levels of potassium can be dangerous. “We know the heart is just one large muscle, so you can imagine how important potassium is for the heart. That electrical activity keeps the heart running,” Pidich says.
In essence, potassium helps the body maintain a delicate balance that makes life possible. “Those electrical impulses are so finely tuned, it balances on a very thin wire,” Lehman 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?
“On average, (Americans) are chronically low on potassium,” Pidich says. 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.
What Happens if I Don’t Get Enough Potassium?
“Very low potassium can kill you, and very high potassium can kill you, so it’s very important to get it right in that balance,” Pidich says. When you don’t have enough potassium in your diet, a condition called hypokalemia, that can disrupt the delicate balance of electrical signaling and lead to noticeable symptoms.
Though sometimes vague, these symptoms can include muscle weakness, muscle twitching and muscle cramping, especially at night. “That muscle weakness can turn into paralysis, so it can actually be deadly,” Pidich says. Abnormal or irregular heart rate, such as palpitations or atrial fibrillation, might also be a sign of low potassium levels. And because there’s so many nerves in the brain, “you can get some psychiatric issues like depression, psychosis or hallucinations that can be linked to low potassium.”
The NIH reports that “the diets of most people in the United States provide much less than the recommended amounts of potassium. Even when food and dietary supplements are combined, total potassium intakes for most people are well below recommended amounts.” People with inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis, and people who have a condition 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. Pidich says alcohol use and excessive caffeine intake can also deplete potassium.
What Happens if I Have Too Much Potassium?
Abnormally high levels of potassium, a condition called hyperkalemia, can cause weakness and fatigue, numbness and tingling, nausea, vomiting, chest pain, palpitations or irregular heartbeats. Again, certain medications can trigger this unusual condition, such as potassium-sparing diuretics, ACE inhibitors (used to treat high blood pressure) nonsteroidal anti-inflammatories (such as ibuprofen and naproxen sodium) and heparin (an anticoagulant, or blood thinner).
Which Foods Are High in Potassium?
Bananas are often listed as the go-to food for people seeking to add potassium to their diets, 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,” Lehman says. Look for whole foods such as fruits and vegetables to offer the highest levels of potassium. This includes bananas, oranges, cantaloupes, honeydew melon, apricots and some dried fruits such as prunes, raisins and dates. “Avocado is another,” Lehman says. “A lot of people don’t realize avocado has a pretty significant amount.” Both sweet and white potatoes are also a rich source of potassium, along with mushrooms, peas, cucumbers, zucchini, eggplant, leafy greens and pumpkins.
You can also find potassium in some fish, such as tuna, halibut and cod. Beans and legumes, such as lima, pinto or kidney beans and lentils are also rich sources. Molasses, yogurt and nuts are also good sources of potassium.
Pidich adds Swiss chard, clams, meat, poultry, pomegranates, edamame, black beans, beets, squash, spinach, arugula, watermelon, coconut water and tomato sauce to the list. She says tomatoes themselves are not particularly high in potassium, but tomato sauce is because “it’s a little more concentrated.” She says a single whole white potato offers about 20 percent of your daily allowance of potassium, so look to add several of the potassium-rich vegetables to your plate every day to make sure you’re getting enough.
It is possible to overdose on potassium, but Pidich says this is very unlikely to happen in a healthy person who simply eats a lot of potassium-rich foods. “If you have too much, you’ll most likely urinate it out. If you’re eating a lot of those high-potassium foods, you most likely will never get high potassium unless you’re on some type of medication, such as a potassium-sparing blood pressure medicine. “No normal person will ever develop high potassium from eating all those foods,” because the body will simply excrete the excess.
Should I Take a Potassium Supplement?
“Unless a supplement is prescribed by your doctor, it’s best to get potassium from dietary sources,” Lehman says. But for some individuals, a supplement might be helpful, and your doctor can help you find the right one for your situation. Lehman 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. The Food and Drug Administration intentionally keeps potassium supplements at a very low dose,” to prevent hyperkalemia.
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