Potassium is a trace mineral found in varying amounts in almost all foods. Vegetables, especially green leafy varieties, are generally our richest sources of potassium.
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 takes a real toll on their health.
This is because Americans fail to regularly eat enough 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.
You can’t 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, unsalted tomato juice can have a ratio of sodium to potassium of 1:3, a much more health-promoting pattern. A good sodium and potassium balance 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.
Generally speaking, the most potassium-rich food sources of potassium are fruits and vegetables. Potassium content within the fruits and vegetables groups 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 plan will easily meet your potassium needs.