Potassium is a mineral found in varying amounts in almost all foods. Vegetables, especially green leafy varieties, are generally our richest sources of potassium.
We list three excellent sources of potassium, 16 as very good sources, and 39 as good sources by our Nutrient Rating System. In other words, over half of our WHFoods provide you with significant amounts of potassium! In fact, all of our WHFoods contain at least some small but measurable amount of this mineral.
Along with sodium, chloride, calcium, and magnesium, potassium is an electrolyte, meaning that it helps to conduct electrical charges in the body. Like all the other electrolytes, our bodies have evolved elaborate systems to control blood levels in a narrow range. This is good news since normal levels of potassium are absolutely critical to life—if potassium levels get too high or too low, the heart and nervous system completely shut down. Luckily, most of us are able to obtain enough potassium from foods to meet our most basic needs. But since just meeting a minimal intake need is not a recipe for health, many people in the United States often fail to obtain optimal amounts of this nutrient, and pay a health cost for it.
This is because Americans fail to regularly eat fresh fruits and vegetables, while eating heavily salted prepared foods. In fact, a recent survey suggests that only about 5% of Americans meet minimal goals for eating fruits and vegetables. If you do not regularly meet these goals, it will be difficult to ensure your potassium intake will be optimal.
It is impossible to understand the role of potassium without addressing sodium as well. Sodium and potassium exist in a partnership, and each important use of potassium requires sodium to maintain balance. Importantly, as average diets in the United States have become depleted in potassium, they have become much more concentated in sodium.
For example, a heavily salted commercial tomato juice—despite containing a potassium rich food like tomato—often contains a ratio of sodium to potassium of more than 2:1. This ratio is not a desirable one! By comparison, our Mushroom, Tomato, and Basil Frittata has a ratio of sodium to potassium of 1:3, a much more health-promoting pattern. In fact, we believe one of the central benefits of the World's Healthiest Foods approach is the way it rebalances sodium and potassium in a manner that is more consistent with good heart and kidney health.
Diets high in potassium are associated with improved blood pressure control. There are several mechanisms contributing to this beneficial effect, including improved kidney function, reduction in blood clotting, and more efficient opening of blood vessels. Because of these important benefits, therapeutic diets aimed at improving blood pressure control often place primary focus on increasing potassium from foods.
A good example of how foods rich in potassium can decrease elevated blood pressure is seen in the DASH (Dietary Approaches to Stop Hypertension) diet trials, where participants with high blood pressure who consumed an average of 8 to 10 total servings of fresh fruits and vegetables per day experienced significant drops in their blood pressure level. These servings focused on whole food choices similar to those featured in our recipes and the diet avoided processed and salt-choked choices like French fries. One key factor in these blood pressure benefits was the healthy balance of potassium to other minerals in these fresh fruits and vegetables.
Perhaps the most important way to ensure strong kidney health is to keep your blood pressure under good control. As discussed above, diets high in potassium are well known to help with this.
In addition, diets rich in potassium have been associated with a reduction in kidney stone risk. This is thought to be because the naturally occurring potassium salts in plant foods help to neutralize acidity in the blood stream. This prevents leeching of calcium from the bones to buffer the acid, which in turn reduces urine calcium, preventing its deposition in the form of a stone. Please note that while diets rich in potassium can be helpful in preventing certain kidney-related problems in a healthy people with good kidney function, persons already known to have kidney problems and who are diagnosed with certain diseases of the kidney may need to carefully regulate their intake of potassium, since their kidneys might not otherwise be able to regulate the levels of potassium in their bloodstream.
Probably the first food that comes to mind when thinking about potassium is the banana. This is not wrong—by our Rating System, bananas are a good source of potassium. But there are 32 foods on our Rating Chart with more potassium per calorie than the banana.
Speaking more generally, the most potassium-rich food sources of potassium are fruits and vegetables. Some legumes, fish, and dairy products can also make important contributions to our daily potassium intake; yet, because these foods have more calories, they are not as highly rated by our Nutrient Richness System. For example, Swiss chard and lima beans both contain nearly 1000 milligrams of potassium, but because a serving of lima beans contains six times as many calories than a serving of chard, the nutrient richness of the chard is higher.
Potassium content within the group of fruits and vegetables can vary widely, even between two foods that seem superficially very similar. For example, a cup of cooked Swiss chard contains more than three times as much potassium as the same amount of kale or mustard greens.
Even with this relatively wide variation, you should feel confident that a largely plant-based diet like the World's Healthiest Foods plan will meet your potassium needs quite readily. In fact, our 7-day meal plan example averages nearly 50% more than the Daily Value (DV) standard for potassium.
Many of our recipes, like this one for Broiled Chicken and this one for Poached Eggs Over Spinach and Mushrooms contain more than half of our recommended daily intake value for potassium. The first of these two recipes contains more potassium than the average adult American woman eats in a single day.
|World's Healthiest Foods ranked as quality sources of|
|Beet Greens||1 cup||38.9||1308.96||28||12.9||excellent|
|Swiss Chard||1 cup||35.0||960.75||20||10.5||excellent|
|Bok Choy||1 cup||20.4||630.70||13||11.8||excellent|
|Brussels Sprouts||1 cup||56.2||494.52||11||3.4||very good|
|Tomatoes||1 cup||32.4||426.60||9||5.0||very good|
|Asparagus||1 cup||39.6||403.20||9||3.9||very good|
|Cabbage||1 cup||43.5||393.00||8||3.5||very good|
|Fennel||1 cup||27.0||360.18||8||5.1||very good|
|Summer Squash||1 cup||36.0||345.60||7||3.7||very good|
|Mushrooms, Crimini||1 cup||15.8||322.56||7||7.8||very good|
|Turnip Greens||1 cup||28.8||292.32||6||3.9||very good|
|Celery||1 cup||16.2||262.60||6||6.2||very good|
|Lima Beans||1 cup||216.2||955.04||20||1.7||good|
|Sweet Potato||1 cup||180.0||950.00||20||2.0||good|
|Winter Squash||1 cup||75.8||494.05||11||2.5||good|
|Romaine Lettuce||2 cups||16.0||232.18||5||5.6||good|
|Mustard Greens||1 cup||36.4||226.80||5||2.4||good|
|Kiwifruit||1 2 inches||42.1||215.28||5||2.0||good|
|Bell Peppers||1 cup||28.5||194.12||4||2.6||good|
|Green Beans||1 cup||43.8||182.50||4||1.6||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%
Like other minerals, potassium is stable to storage. There are not significant changes to the bioavailability of potassium over the storage life of any important food. You do not need to take any special storage precautions to maintain the potassium content of your foods.
Cooking vegetables can lead to loss of some or much of their potassium content. If you follow our recipes carefully, however, enough potassium will be preserved to provide you with health benefits. For example, lightly boiling spinach in the way we describe in our spinach profile leads to a loss of about one-third of the total potassium; yet, as you see from the chart below, cooked spinach still features more than 800 milligrams of potassium—over 20% of the Daily Value (DV).
The key to preserving potassium content of food during cooking is to minimize duration of contact of that food with cooking water. For instance, boiling spinach for a second minute increases the loss of potassium to up to 72% of its initial content. The World's Healthiest Foods cooking methodology is designed to minimize mineral losses, so we recommend you pay close attention to cooking times to ensure good potassium retention in your foods.
It is not uncommon to find added potassium compounds in processed food. Examples include potassium sorbate added to foods as a preservative and mold inhibitor; potassium bisulfite added as a preservative; potassium chloride as a salt replacer; potassium bitartrate as a flavor modifier; and dipotassium phosphate as a stabilizer and de-acidifier. In many cases, the addition of potassium during processing does not add large amounts to average daily potassium intake. However, in the case of processed products like salt substitutes, the addition of potassium can be substantial. Some salt substitute brands using potassium chloride provide over 600 milligrams of potassium in one-quarter teaspoon.
We usually use the Dietary Reference Intake (DRI) standards from the National Academy of Sciences (NAS) when setting our own nutrient recommendations. One subcategory of DRIs are the Adequate Intakes, or AI standards. Based on these AIs, more than 98% of all Americans fail to get enough potassium on a daily basis. With other nutrients, we usually focus on ages, gender, or disease conditions as special risk categories for deficiency. When we discuss potassium, though, virtually everybody is at risk for deficiency.
Although all groups appear to be doing poorly, women and African-Americans appear to have the lowest potassium intake. The high risk of deficiency in Americans is directly related to our over-reliance on heavily processed foods as our main calorie sources. Whole foods meals like the recipes we feature here on the World's Healthiest Foods site should help to ensure low risk of potassium deficiency. Here is an example of a 10-minute recipe—Mediterranean-Style Salad—that contains nearly half of the daily recommended intake value for potassium.
Even in people who get plenty of potassium, fluid loss can lead to problematic loss of potassium. For instance, people undergoing heavy physical training or who work outdoors on a hot day can run into this problem.
A more common reason to see low potassium levels is in people suffering from acute or chronic diarrhea. People with ongoing gastrointestinal illness may need to be careful to maintain normal potassium levels.
Use of certain prescription and over-the-counter medications can also increase risk of potassium deficiency.
As mentioned above, the relationship between potassium and sodium is critical to the health benefits of diets high in potassium. The ratio of sodium to potassium in a modern, processed food diet is likely to be close to 5:1, with five times as much sodium as potassium. The U.S. would be a good example of an industrialized country with this type of high sodium:potassium ratio from processed foods. In non-industrialized countries where foraging and hunting determine the nature of the food supply, this ratio can be completely reversed, with five times as much potassium as sodium. Communities in some parts of Tanzania would be a good example of this type of hunter-gatherer culture.
Researchers do not know the exact best ratio of potassium to sodium in a meal plan. But they do know that the average U.S. diet is tilted way too far in the direction of sodium and not nearly enough toward potassium.
As a general rule of thumb, cheeses, breads, canned soups, and fast foods would be foods with much more sodium than potassium. Fruits, vegetables, and non-cheese dairy products should all contain more potassium than sodium.
|Food||Potassium (mg)||Sodium (mg)||Sodium:Potassium Ratio|
|Fast food cheeseburger||375||1137||3.0|
As the above chart should make clear, fresh and whole foods tend to have more potassium than sodium, while prepared foods tend to feature the opposite ratio. Because the World's Healthiest Foods recipes tend to feature little to no added sodium, we are able to preserve this beneficial balance of sodium and potassium throughout our approach.
Some, but not all, research suggests that a diet rich in potassium may help to prevent loss of calcium in the urine. The idea here is that potassium salts found in fruits and vegetables tend to counter the effects of diets high in acid-forming proteins and that this in turn reduces the need to pull calcium from the bones to buffer the acid. To date, researchers have shown short-term benefits of dietary potassium on measures of calcium balance but have not been able to demonstrate improved bone health.
For healthy people with normal kidney function, there is not any known risk of toxicity from excessive dietary potassium under any circumstance. People with conditions affecting fluid balance—including kidney disease, some hormonal conditions, and heart failure—should work with their doctor before deliberately trying to increase their dietary potassium.
It's also worth noting here that the National Academy of Sciences (NAS) has chosen not to set a Tolerable Upper Limit (UL) for potassium.
In 2004, the National Academy of Sciences (NAS) set Dietary Reference Intake (DRI) levels for potassium. Specifically, these levels were Adequate Intake (AI) levels for different age and gender groups as follows:
The Daily Value (DV) for potassium is 3,500 milligrams. This DV is the standard that you will see on food labels. It is also the standard that we adopted as our WHFoods standard.
There is currently no Tolerable Upper Intake Level (UL) for potassium.