Welcome back to Nutrition A to Z! If you have been here from the start, you know how this works. One nutrient at a time: what it is, what it does for you, where to find it, and my favorite part, the teammates it works with.
Last month, magnesium made me a promise I intend to keep. Magnesium is the gatekeeper that holds potassium inside your cells, which means potassium was always going to be next. Nutrients work in teams, and this is one of the closest friendships in the whole series.
And honestly, the timing could not be better. November is harvest season. Potatoes, sweet potatoes, squash, beans, and every side dish that is about to land on the Thanksgiving table are some of the richest potassium foods there are. Fall is basically handing this one to us.
The quick version
Potassium is an electrolyte that helps your nerves fire, your muscles contract and your heart keep its rhythm.
It works like a seesaw with sodium, and that balance is a big part of healthy blood pressure.
The Dietary Guidelines for Americans name it a nutrient of public health concern, because most of us do not get enough.
It is the balancer of the nutrient world, and it leans on magnesium to stay where it belongs.
What it is
Potassium is a mineral and an electrolyte, which means it carries a tiny electrical charge when it dissolves in your body's fluids. That charge is the whole secret. Your cells use it to send signals, move fluid and keep things running.
Almost all of the potassium in your body lives inside your cells. Sodium is the opposite, and mostly lives outside them. Your cells work constantly to keep it that way, using a little pump in every cell membrane that moves potassium in and sodium out, over and over, all day long. That difference between the inside and the outside is what lets a nerve fire and a muscle move.
Your body cannot make potassium, and it cannot store very much of it either. Your kidneys are the managers here, keeping the amount in your blood in a narrow, careful range. That is why potassium is a nutrient you need to keep showing up for every day, not something you can stock up on once and forget.
Potassium is the quiet mineral that keeps every cell in balance, one heartbeat at a time.
What it does
Keeps your heart in rhythm. Every heartbeat depends on the electrical difference that potassium helps create. It is one of the reasons doctors keep such a careful eye on potassium, and one of the reasons it deserves our respect.
Helps your muscles and nerves talk. From the muscles in your legs to the ones that move food through your digestive system, potassium is part of every signal that says contract, relax, go. When potassium runs low, muscles can feel weak or crampy and everything feels a little sluggish.
Supports healthy blood pressure. This is the big one, and it is where the seesaw comes in. Potassium helps your body let go of extra sodium, and it helps the walls of your blood vessels relax. The National Institutes of Health describes a strong connection between getting enough potassium and healthy blood pressure, and for women heading into our late forties and fifties, when blood pressure so often starts creeping up, that matters a great deal.
Helps protect your bones. Potassium-rich fruits and vegetables appear to help your body hold on to calcium rather than lose it. With bone health becoming such a priority as estrogen shifts through perimenopause and menopause, I love that potassium quietly joins the bone-support team alongside calcium, magnesium, vitamin D and vitamin K2.
Plays a part in blood sugar. This one fits right in with Sugar Detox month. Potassium is involved in how your body releases insulin, and research has linked lower potassium intake with less steady blood sugar over time. It is one more reason the plate I keep talking about, full of vegetables, beans and whole foods, does so much more than it looks like it is doing.
Keeps your fluids where they belong. Along with sodium, potassium helps manage the water balance inside and outside your cells. Think of it as part of your body's internal plumbing crew.
Where you get it
The season's best source: your produce drawer
Here is the beautiful thing about potassium. It lives in exactly the foods that are in season right now. A baked potato with the skin, a bowl of lentil soup, roasted acorn squash, a handful of dried apricots. This is cozy, comforting, fall food, and it is loaded.
Food
Food first, always, and this list is a delicious one. Here are some of the top sources, using numbers from the National Institutes of Health.
Dried apricots, 1/2 cup: 755 mg
Lentils, cooked, 1 cup: 731 mg
Acorn squash, mashed, 1 cup: 644 mg
Prunes, 1/2 cup: 635 mg
Raisins, 1/2 cup: 618 mg
Potato, baked, flesh only, 1 medium: 610 mg
Kidney beans, canned, 1 cup: 607 mg
Orange juice, 1 cup: 496 mg
Soybeans, cooked, 1/2 cup: 443 mg
Banana, 1 medium: 422 mg
Spinach, raw, 2 cups: 334 mg
Chicken breast, cooked, 3 ounces: 332 mg
Yogurt, nonfat, fruit, 6 ounces: 330 mg
Salmon, cooked, 3 ounces: 326 mg
Tomato, 1 medium: 292 mg
Broccoli, cooked, 1/2 cup: 229 mg
Cashews, 1 ounce: 187 mg
Everybody thinks of bananas, and bananas are lovely, but look at what beats them! Lentils, beans, potatoes and squash all leave the banana behind. If you want one easy win this week, make a pot of lentil soup or bake a few potatoes, and eat the skins too, since they bring even more.
One more thing worth knowing. Processing tends to strip potassium out and add sodium in, which tips the seesaw the wrong way twice. That is why a plate built from whole foods makes such a difference here.
Supplements
Now let me be honest with you, the way I always try to be. Most of us simply are not eating enough fruits, vegetables and beans to hit the mark, and the national data shows it. That gap is real, and filling it thoughtfully is worth doing.
With potassium, I lean hardest on food, and here is why. Your body handles potassium very carefully, and it is one of the few nutrients where a big dose all at once is not a good idea. That is why most potassium supplements on the shelf contain only a small amount per pill. Where supplements really shine for potassium is as a helper alongside food: in a quality multi-mineral, in an electrolyte formula on a hot or sweaty day, or paired with magnesium so the two can do their work together. When I look at a potassium-containing product, I look for three things:
A formula that pairs potassium with magnesium, because potassium works best when magnesium is there to hold it in place.
No added sugar, which is a real trap with electrolyte drinks and powders, and very much on theme for Sugar Detox month.
Quality you can trust, from a company that is open about its sourcing and testing.
A warm heads up. Potassium is one nutrient where too much can be just as serious as too little. If you have any kidney concerns, or you take blood pressure medications such as ACE inhibitors or ARBs, or a potassium-sparing diuretic, your body may hold on to potassium more than usual. The same goes for salt substitutes, which are often made from potassium chloride. Please talk with your doctor or pharmacist before adding a potassium supplement or switching to a salt substitute.
Synergy partners: potassium's dream team
If vitamin D was the messenger and magnesium was the activator, potassium is the balancer. Its whole job is keeping things steady, and it does that best with a few close friends.
Magnesium, the gatekeeper
We met this partnership last month from magnesium's side, and it is just as important from this side. Magnesium powers the little pumps that keep potassium inside your cells. When magnesium runs low, potassium leaks out and slips away, and it becomes very hard to bring potassium back up until magnesium is sorted out first.
So if you have ever wondered why you can eat all the bananas in the world and still feel like something is missing, magnesium is worth a look.
Where to find the pair together: spinach, beans, potatoes, avocado, yogurt and salmon. So much overlap!
Sodium, the other end of the seesaw
Picture a seesaw on a playground. Potassium sits on one end, sodium on the other. When they are balanced, everything rides smoothly. Most modern eating piles far too much onto the sodium side, mostly from packaged and restaurant food, and not nearly enough onto the potassium side.
Sodium is not the villain here. You need it! The goal is balance, and the easiest way to get there is to add more potassium-rich whole foods rather than obsessing over every grain of salt.
The simple swap: cook more at home, where you control the salt, and fill half your plate with vegetables. You will tip the seesaw back without even trying.
Calcium, the bone buddy
Potassium-rich fruits and vegetables help your body keep calcium where you want it, in your bones. Together with magnesium, vitamin D and vitamin K2, they make up the bone-support crew I keep coming back to in this series.
Where to find calcium: yogurt, sardines with the bones, leafy greens, almonds and fortified foods. Yogurt and leafy greens are pulling double duty on this team.
Who tends to run low
Honestly, most of us fall short of what we need from food. But you are more likely to need extra attention here if you:
Eat mostly packaged or restaurant food and not many fruits, vegetables or beans
Take a loop or thiazide diuretic, which can increase potassium losses
Use laxatives often, or have had a stretch of vomiting or diarrhea
Have a digestive condition that affects absorption, like Crohn's disease or ulcerative colitis
Are low in magnesium, since potassium is hard to hold on to without it
Sweat a lot, from hard workouts, hot yoga or a warm workplace
Partner with your provider
You and your healthcare provider are on the same team. Potassium from food is wonderful and very hard to overdo when your kidneys are healthy. Supplements are a different conversation, and with potassium, more is truly not always better. So bring it to your next appointment. Here are five questions worth asking:
Looking at how I eat and how I have been feeling, is potassium something I should be paying more attention to?
Do any of my medications raise or lower my potassium, or make a supplement or salt substitute a bad idea for me?
Given my kidney function, is a potassium-containing supplement or electrolyte product a safe choice for me?
My blood pressure has been creeping up. How do potassium and sodium fit into the plan for me?
Should I be looking at magnesium alongside potassium, and how would we follow up from here?
My take
I love that potassium is such an everyday mineral. It is not exotic and it is not expensive. It is the baked potato, the pot of lentils, the squash on the counter and the spinach in the fridge. It is fall food and comfort food, and it is quietly keeping every cell in your body in balance.
And it proves my favorite point one more time: nothing works alone. Potassium needs magnesium to stay put. It needs sodium to balance against. It works with calcium to protect your bones. When you eat the whole plant food, you get the whole team, and a thoughtful supplement fills in where real life leaves a gap. That is the holistic approach I believe in with my whole heart.
So this Thanksgiving, when the potatoes and the squash come around, take a little extra. You have my full permission. Next up in Nutrition A to Z, we will stay on the bone-support crew and give calcium its turn.
Want a little help tipping the seesaw? My free Healthy Pantry Swap Guide makes it easy to trade high-sodium staples for better ones, and the Hypertension Guide walks through the everyday habits that support healthy blood pressure. Both are waiting in my free resource library.
This post is for education only and is not medical advice. I am a Certified Holistic Health Coach. I do not diagnose, treat, prescribe for or cure any medical condition, and nothing here is intended to do so. Please talk with your healthcare provider before starting any supplement, especially if you are pregnant, nursing, taking medication, or managing a health condition.
Where this comes from
National Institutes of Health, Office of Dietary Supplements: Potassium fact sheets for health professionals and consumers, including food source amounts and medication interactions
U.S. Department of Agriculture and U.S. Department of Health and Human Services: Dietary Guidelines for Americans, 2020 to 2025, on nutrients of public health concern
Linus Pauling Institute, Oregon State University: Potassium
American Heart Association: How Potassium Can Help Control High Blood Pressure
Huang CL and Kuo E, Journal of the American Society of Nephrology, 2007: "Mechanism of Hypokalemia in Magnesium Deficiency"
National Institutes of Health, Office of Dietary Supplements: Magnesium and Calcium fact sheets