Why Your Body Needs Potassium (and How to Get Enough) - Ask a Nutritionist

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Transcript

Alyssa: Welcome back to Ask a Nutritionist, our weekly mini episode of Dishing Up Nutrition. I'm Alyssa Krejci, Registered Dietitian with Nutritional Weight & Wellness. Today, we're talking about a mineral that doesn't always get the attention it deserves, potassium. When most people hear potassium, they probably think of bananas and maybe muscle cramps.

And while bananas are certainly a great source of potassium, there's much more to this mineral than bananas and muscle cramps.

Roles potassium plays in the body

Potassium is an essential electrolyte involved in everything from your muscle contraction and nerve communication, your heart rhythm, and fluid balance in the body. And while most people can get plenty of potassium from food, having potassium that is either too low or too high in the blood can become a serious health concern.

So today, we're going to talk about why potassium's so important, which foods are a rich source of potassium, and what symptoms might indicate potassium's off balance.

Let's start with the basics of why potassium's so important. Potassium is a mineral and an electrolyte. Electrolytes are minerals that carry an electrical charge and help regulate important processes through the body.

Potassium is particularly important because it helps cells, nerves, muscles, including the heart, function properly. Almost all the potassium in your body is located inside your cells, and only a very small amount actually circulates in your bloodstream. That may sound like a minor detail, but it's incredibly important.

Your body carefully maintains the difference between potassium inside and outside your cells. The potassium gradient helps create the electrical signals that allow nerve cells to communicate and muscles to contract. Your heart is a muscle, which means potassium plays an important role in maintaining a normal heartbeat.

When potassium levels become significantly too low or too high in the blood, it can interfere with the electrical activity of the heart. Potassium works together with sodium to help regulate fluid balance. Sodium is the main electrolyte outside the cells. It draws water into the space outside your cells, while potassium is the primary electrolyte inside the cells that helps control fluid balance and cell function.

The relationship between sodium and potassium is one reason potassium-rich foods are emphasized as part of a heart-healthy diet. The American Heart Association recommends an intake between thirty-five hundred and five thousand milligrams of potassium daily from food for both prevention and in the management of high blood pressure.

Research and dietary guidance have associated adequate potassium intake with healthier blood pressure levels, particularly because potassium helps counter some of sodium's effect on blood pressure. It helps the kidneys flush out extra sodium through urine, lowering total fluid volume and reducing the stiffness and tension sodium can cause in the arteries.

Potassium is also involved in helping nutrients move into cells and waste products move out of cells. So when we talk about potassium, we're really talking about a mineral, an electrolyte that helps your body perform some of its most basic functions.

How much potassium is needed/day?

Now, how much potassium do you actually need in a day? For adults, the recommended daily intake minimum or RDA is approximately thirty-four hundred milligrams per day for men and twenty-six hundred milligrams per day for women. The FDA classifies the percent daily values for potassium based off of a standard forty-seven hundred milligram daily reference amount.

So when you look at a food label, you're going to be seeing a percentage under DV or daily value. The FDA label classification follows a five/twenty rule, meaning if it's listed as five percent or less, it's considered low in a particular nutrient for that serving listed, and if it's twenty percent or more, it's considered high for that nutrient in that amount serving listed.

The National Kidney Foundation, however, equates a six percent to nine percent daily value serving to be classified as a high potassium food and greater than nine percent daily value to be a very high potassium food. A daily value of three percent or less is then considered a low potassium food.

Many of your highest potassium foods, vegetables and fruits, are not always going to come with a food label. Keep in mind all these numbers are general recommendations and individual needs can vary.

One important point to note here is that the majority of people don't actually consume an adequate amount of potassium, and that's often because they're simply not eating enough of the whole foods that naturally contain potassium, your vegetables and your fruits.

If you're thinking, " I think I'm in that boat," instead of first off jumping to the thought, " I should grab a potassium supplement," a better first question to ask yourself is, "Am I regularly eating enough naturally potassium-rich foods in my diet? And if not, how can I boost the intake to get what I need?"

Potassium-rich foods

So let's talk about some of the best options for potassium that we can include. One of the greatest things about potassium is it's found in a wide variety of real whole foods. And yes, it is common to associate bananas with potassium, but bananas are not the only high potassium food.

Bananas became the poster child for teaching children and adults about potassium because they're first inexpensive, they're portable, recognizable, and they don't require a whole lot of preparation. Eat a banana for potassium. It's a quick and easy nutrition message.

They're one of the few foods that became almost synonymous with a specific nutrient. Similar examples are oranges for vitamin C or carrots for vitamin A and beta carotene. A medium banana, or roughly about four ounces of banana, has around four hundred milligrams of potassium.

You can also get roughly the same amount by eating a half a large avocado, or about three ounces. Other high potassium sources include potatoes, around three hundred and fifty milligrams for three ounces of russet potato. Sweet potatoes, winter squash, and things like canned pumpkin are also great source of potassium.

Leafy greens, including spinach, Swiss chard, beet greens can contribute significant amounts of potassium, along with foods like tomatoes and tomato products. Then we have fruit. Fruits, besides bananas, that are high in potassium include things like your oranges, cantaloupe, kiwi fruit, mango, and dried fruits such as apricots, raisins, and prunes.

Around eight dried apricot halves or just about one ounce, twenty-eight grams of dried apricots provide your body with around seventeen grams of carbohydrates, two grams of fiber, and three hundred and twenty-five milligrams of potassium. The fresh apricot portion comparable when they're in season is going to be around four whole apricots or about five ounces of fresh apricot halves.

Legume vegetables are potassium powerhouses. Foods like lentils, kidney beans, and edamame can provide several hundred milligrams per half-cup serving. One of my favorites is edamame. A three-ounce portion, around three-quarter cup of shelled edamame, has a little over four hundred and fifty milligrams of potassium.

Some dairy products like milk and yogurt also contribute significant potassium amounts. Although other dairy foods like your cheese, cream, or butter contain very little potassium. And let's not forget animal protein foods like fish, chicken, beef, they also contain some potassium as well.

For example, your salmon or your chicken in a typical serving size is going to provide you with several hundred milligrams of potassium. So if you're trying to increase potassium through food, it is possible to get enough from eating a variety of real foods like we always talk about here on Dishing Up Nutrition.

Think of colorful vegetables, legume vegetables, starchy vegetables, fruits, dairy, and animal proteins. Here's an easy way to think about meeting daily potassium needs. Ask yourself, "How can I include potassium-rich foods at each meal throughout the day?"

For breakfast, that could be six ounces of Greek yogurt paired with four ounces of sliced kiwi fruit and two to three tablespoons of almonds. All together, you will have around seven hundred and sixty milligrams of potassium in one yogurt bowl.

At lunch, maybe you're making a salad with four ounces of spring greens, two ounces of cucumber, a couple ounces of avocado, a couple ounces of diced tomatoes, two ounces of edamame, and for additional protein, three ounces of tuna and a hard-boiled egg.

This hearty salad will provide you with around ten grams of fiber and a little over one thousand three hundred and fifty milligrams of potassium. At dinner, you could have four ounces of baked chicken with five ounces of baked sweet potato and five ounces of Brussels sprouts. That meal alone will provide you with around fifteen hundred milligrams of potassium.

Suddenly, you'll be getting potassium from multiple real food sources at every meal, and added together, those meals provide you with around thirty-six hundred milligrams of potassium. That's not including any snacks.

What if potassium is too low on a blood test?

Now, what if your potassium is too low on a blood test? This is where things get a little more complicated. Remember, potassium is mainly inside your cells. Extracellular potassium influences muscle activity, especially the heart muscle. Low blood potassium is called hypokalemia, and it may induce muscle weakness and cardiac arrhythmia.

If you've had blood work and your blood potassium comes back low, your healthcare providers will look at the whole picture and not automatically assume you're simply not eating enough potassium. There are several possible causes that's not related to the potassium you're eating.

One of the most common is losing too much potassium. For example, prolonged diarrhea or vomiting can cause potassium losses. Heavy sweating can contribute in certain circumstances as well. Certain medications can also lower potassium, like diuretics, which can increase the amount of potassium that is excreted in the urine. Certain laxatives can also contribute to potassium loss.

Kidney and adrenal conditions can affect potassium regulation as well. Another important piece of the puzzle is magnesium, another electrolyte. If magnesium is significantly low, it can make it harder to correct low potassium because magnesium deficiency can increase potassium losses.

So if someone has a low blood potassium, a healthcare provider will look at the big picture rather than simply recommending a potassium supplement. We’ve got to think about multiple factors of what's going on and why that blood potassium is running low.

It's worth emphasizing that low dietary potassium alone isn't usually the reason someone develops clinically significant hypokalemia. And that's why a significantly abnormal potassium blood test shouldn't be something you try to correct on your own with a high-dose supplement.

What if your potassium runs high on a blood test?

It deserves further medical evaluation. And what about the other side of the spectrum if your potassium in the blood is running high? We'll go to the other side. So high blood potassium is called hyperkalemia, and it may cause cardiac arrest. People sometimes hear that potassium is healthy and assume that more must be better.

And while, yes, for most people, we do need a significant amount of potassium in a day to support a heart-healthy diet, things are not always this black and white. Potassium is one of those nutrients where balance matters. One of the primary ways your body maintains potassium balance is through your kidneys.

Your kidneys filter your blood and remove excess potassium through your urine. If kidney function is impaired, potassium can build up in the blood. Certain medications can also increase potassium. These include some medications used for blood pressure and heart conditions such as ACE inhibitors, ARBs, as well as potassium-sparing diuretics.

People with certain medical conditions, including chronic kidney disease, heart failure, adrenal insufficiency, and type one diabetes, may also have a higher risk of hyperkalemia. If your potassium is unexpectedly high on a blood test, again, it's important to have that follow-up with your healthcare provider.

When is supplementing appropriate?

Now, back to that note on supplements. You might be thinking, " I don't eat a lot of vegetables or fruits, Alyssa. Can I just supplement to make up the difference and meet my potassium needs?" And again, the answer is potassium is not a supplement I recommend casually taking.

For most healthy people with normal kidney function, getting potassium from food, not supplements, is the safest option with the most health benefits. The body can generally eliminate excess dietary potassium through the kidneys.

Supplements are different from whole foods. They deliver a concentrated amount of potassium relatively quickly, and taking too much supplemental potassium can cause potassium levels in the blood to become dangerously high. This is particularly concerning if you have kidney disease or take medications that can increase potassium.

So before ever taking a potassium supplement, it's very important to talk with your healthcare provider. Potassium is essential, but more isn't always better. If you have a normal potassium level and healthy kidney function, there's generally no reason to specifically supplement potassium. Eat your whole potassium-rich foods, your fruits, your vegetables, beans, other legumes. It's a very healthy dietary goal to include vegetables and fruits at every meal, and that's going to support your overall health.

Recap

So to recap, potassium is an essential electrolyte that supports nerve function, muscle contraction, including your heart, and fluid balance. You can find it in a wide variety of real whole foods, including both plant and animal foods.

Low potassium in the blood can happen because of fluid losses, certain medications, gastrointestinal losses, kidney or hormonal problems, and other medical conditions. And a high blood potassium is often related to impaired kidney function, certain medications, or other medical conditions.

And when it comes to supplementation, potassium is one nutrient where I do not recommend the more is better approach. Food first is the safest strategy. Potassium supplements should only be used under the guidance of a healthcare professional.

The next time you think about potassium, don't just think about bananas. Think about a variety of foods: leafy greens, squash, avocados, kiwi fruit, beans, yogurt, fish, meat, potatoes.

Really enjoy a diet filled with a variety of color, variety of whole foods. Your heart, your muscles, your nervous system will be thankful. Thank you for listening to this week's Ask a Nutritionist. If you have a topic that you'd like answered on a future episode, visit our Dishing Up Nutrition Facebook page, or submit a question to email@weightandwellness.com. I'll talk to you next time.

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