If you’re looking to lower, or prevent, high blood pressure, you might want to add more potassium-rich foods to your diet. Increasing potassium may be as good if not better, than limiting salt intake. And eating more of something is always easier than eating less of something.
What is blood pressure?
Blood pressure is a measure of the pressure of your blood against the walls of your arteries. No different than the pressure of water in your garden hose or household taps. But unlike your garden hose, your heart and arteries can change to alter your blood pressure. A faster and stronger beating heart will lead to a higher blood pressure. Your arteries can also change in size. As they constrict, blood pressure goes up. As they widen, blood pressure goes down. Your body is skilled at ensuring your blood pressure is in an acceptable range for what you’re doing at the time.
A blood pressure measurement is given as two numbers. One on top of the other. The first, or top number, is generally the higher of the two. It’s the systolic blood pressure. This the pressure in your arteries when your heart beats and blood rushes through. The second, is the diastolic blood pressure. This is the pressure in the arteries between heart beats when blood flow is much less.
A lot of focus is spent on increasing awareness of high a blood pressure. That’s why you can find a blood pressure monitor in almost every drug store. But it’s not a case of lowering your blood pressure to zero. That would mean your blood wasn’t moving at all. This would be very problematic (to say the least). No, your body needs a certain blood pressure to ensure your organs and working muscles get the oxygen and nutrients they need.
Prevalence of High Blood Pressure
An ideal blood pressure is considered less than 120/80 mmHg. High blood pressure, or hypertension, is generally considered if systolic is ≥140 or diastolic ≥90 mmHg. In people with diabetes or kidney disease, hypertension is ≥130/80 mmHg. Some organizations consider this value to be high regardless of health status.
Nearly one in four adults have high blood pressure, using ≥140/90 mmHg definition. High blood pressure (hypertension) is a concern as it is a risk factor for many diseases. Ongoing hypertension is associated with increased chances for kidney and heart disease, stroke and early death.
A high blood pressure can be the result of many things; biochemical changes, stiffening of arteries, kidney problems. But in most people, we don’t know what causes high blood pressure. It tends to occur over the years. And is generally higher in older people as our arteries become less compliant (stiffer) with age.
Potassium- The Forgotten Nutrient
While medications may often be used to lower high blood pressure, lifestyle changes are the first treatment and used for preventing high blood pressure. This includes increasing activity, weight loss and changes in what one eats. When we think of how our food affects blood pressure, the first thing most of us think of is sodium—We need to get our sodium down. We can’t eat this, or should avoid that food because it’s high in sodium. Whether sodium is as bad as it’s made out to be is discussed is controversial and the subject of an earlier blog of mine.
What gets lost in the sodium debate is the need for more potassium. Potassium is extremely important and many of us don’t get the necessary amount. Our bodies use potassium for a number of things such as muscle contractions and nerve impulses. When it comes to blood pressure, potassium helps to regulate sodium levels, along with relaxing the arteries, which together can lower blood pressure. High intakes of potassium are associated with more sodium being excreted through urine (natriuresis), which is a good thing.
Guidelines from the Institute of Medicine recommend a daily intake of 4700 mg/day for adult men and women. The problem is that the average intake is less than half that in the US. This is likely due to a Western-type diet which is low in fruits and vegetables.
The Benefits of More Potassium
Studies of diets high in potassium have reported substantial reductions in blood pressure. The most popular is the DASH (Dietary Approaches to Stop Hypertension) diet of increased fruits and vegetables, along with lean meats, fish and whole grains. After 30 days, the DASH diet lowered blood pressure similar to taking an antihypertensive medication. The greatest effects were on those people with the highest sodium dietary intake. Even though the DASH diet increases potassium intake, it’s much more than that, it’s an overall healthy nutrition regimen, so one can’t say the blood pressure lowering is due entirely to higher potassium.
While getting your nutrition from whole foods is the best way, it makes it difficult to determine what is the effect of individual nutrients. In this case, the study of supplements is helpful. A review of randomized controlled studies found that potassium supplementation can result in an average reduction in blood pressure of 4.3/2.5. A modest reduction but relevant, nonetheless.
But how does potassium intake relate to heart disease, stroke and early death? Work from our PURE study in over 100 000 people found higher potassium was associated with less heart disease and premature death. The limitation of the PURE study is that it’s observational and can’t indicate that high or low potassium prevents or causes premature death, however, it is consistent with other observational studies. Supporting these findings is an earlier, small randomized trial that found less heart disease using potassium enriched salt compared to regular salt.
How to get More Potassium
While bananas or often thought as a go-to food for potassium, there are many other foods that carry more of a potassium punch. Red kidney beans are packed with potassium (plus they’re a good source of protein and fibre). One cup (raw) gives you nearly 2600 mg of potassium (cooked is 718 mg). That’s more than half your daily intake. Green leafy vegetables, nuts, squash, tomatoes and avocados are also great sources (for a full list see here).
And combining foods can really add up. For example, creating a salad which contains spinach (1 cup), almonds (1/4 cup), canned mandarin oranges (1/2 can), red kidney beans (1/6 cup), tomato, pumpkin seeds (1/4 cup) and half an avocado. For some, it may not be enough as a meal by itself, but it does contain 1700 mg of potassium, which is over a third of the recommended daily intake.
The one situation where people may need to be cautious about too much potassium in their diet is if they have problems with their kidneys. These people should seek advice from a physician or clinical dietitian before increasing potassium. For the overwhelming majority of us, we can definitely benefit from getting more potassium. In doing so, we’ll also improve our overall diet as foods high in potassium are full of other essential nutrients as well.
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This post was originally published on April 11, 2018 and updated on May 25, 2022.