Can potassium-rich foods lower blood pressure?

What is potassium (kalium)?

Potassium (also known by its Latin name, kalium) is an essential mineral. This means your body cannot make it on its own, so you need to get it through your diet.

It’s found naturally in many foods, such as:

• fruit
• vegetables
• nuts
• seeds
• pulses
• meat
• fish
• dairy.

Most of the potassium in your body is found inside your cells, including the heart cells.

It works closely with sodium, the mineral found in salt, to maintain a healthy fluid balance. They also move nutrients and signals in and out of cells.

This supports your body’s electrical system, which controls your heartbeat, regulates your blood pressure, and helps your heart muscle contract in a regular rhythm.

• Learn more about how a healthy heart works.

How much potassium do you need?

The World Health Organization recommends adults get 3,510mg of potassium a day from food to reduce their risk of high blood pressure and cardiovascular disease. 

However, working age adults in the UK typically consume far below the recommended amount, having around 2,500mg potassium a day on average, according to the UK Government’s 2019 to 2023 National Diet and Nutrition Survey (NDNS).

At the same time, UK adults eat more than the recommended 6g of salt or 2,400mg of sodium per day.

On average, they have 8.4g of salt or 3,300mg of sodium a day, according to the 2018 to 2019 NDNS.

This can lead to heart health issues because eating too little potassium and too much salt can result in high blood pressure, which can increase your risk of cardiovascular diseases like heart attack and stroke.

Does potassium lower blood pressure?

Over the past decade, research has consistently found that eating more potassium-rich foods can help lower blood pressure, especially in people who have high blood pressure or eat a lot of salt.

This is because potassium helps the kidneys remove sodium from your blood and pass it out of the body in urine.

In turn, this reduces the amount of fluid in your bloodstream and helps the blood vessels relax, which brings down blood pressure.

Research suggests increasing potassium intake can reduce the top number on a blood pressure reading (systolic blood pressure) by around 5.3 mmHg and the bottom number (diastolic blood pressure) by around 3.6mmHg in people with high blood pressure.

These may sound like small changes, but even a modest reduction in blood pressure can lower the risk of heart attack and stroke.

How can you eat more potassium?

Most healthy adults can get enough potassium from a balanced diet.

However, you may not be getting enough if your diet is high in processed foods and low in fruit and vegetables.

Many ultra-processed foods contain less potassium than fresh or minimally processed foods.

To eat more potassium, try to cook more meals from scratch and aim for at least 5 portions of fruit and veg a day.

Some fruit and veg contain more potassium than others – for example, you’ve probably heard that bananas are high in potassium, but dried apricots, spinach, sweet potatoes and avocados are also good sources.

Tinned vegetables without added salt or sugar, frozen vegetables and ready-chopped vegetables all count towards your 5-a-day too.

Plus, beans, lentils, nuts, seeds, low-fat dairy foods, fish and lean meats can also contribute to your potassium intake.

You can find more potassium-rich foods in the table below.

30 foods that contain potassium

Source: McCance and Widdowson’s Composition of Foods Integrated Dataset. Rounded to nearest 5mg.

What’s the best diet to lower blood pressure?

If you want to reduce your blood pressure, following the DASH (Dietary Approaches to Stop Hypertension) diet can help.

Researchers developed the diet in the 1990s to help people eat more nutrients, such as potassium, calcium and fibre, and less salt to help lower blood pressure naturally.

In the first study of the diet, people were either given the DASH diet, which had a target daily intake of 4,700mg of potassium, or a control diet, which only had 1,700mg of potassium per day.

It found that the systolic and diastolic blood pressure of people without high blood pressure who followed the diet decreased by 5.5mmHg and 3.0mmHg more than those on a control diet.

People with high blood pressure saw it drop further, with an average fall of 11.4mmHg for systolic blood pressure and 5.5mmHg for diastolic.

A later review published in 2019 of 7 meta-analyses linked the high-potassium DASH diet to a 20 per cent lower risk of developing cardiovascular disease.

What are low potassium symptoms?

A low level of potassium in the blood is called hypokalaemia, but it’s rarely caused by diet alone.

Prolonged diarrhoea, throwing up, some medicines or underlying medical conditions can all lead to low potassium.

Symptoms can include tiredness, nausea and high blood pressure.

Very low levels can cause muscle weakness or cramps, constipation, tingling, numbness and abnormal heart rhythms (arrhythmias).

Should you take a potassium supplement?

In general, potassium supplements are not recommended, especially for older people and those with kidney disease or heart failure, unless your doctor has told you to take them.

If your potassium is too low, your doctor may prescribe potassium supplements and give you advice on how to get more through your diet.

What about electrolyte drinks?

Electrolyte drinks contain minerals such as potassium and sodium (salt).

They're designed to restore electrolyte (mineral) levels in your body which have become imbalanced from dehydration after gut illnesses, such as vomiting and diarrhoea, or sweating during very intense exercise.

However, for most people, these drinks are no more hydrating than plain water, and you do not need to drink them. They’re not suitable for people with heart failure or kidney disease.

They also often come with added sugar.

What are high potassium symptoms?

A high level of potassium in the blood is called hyperkalaemia.

Symptoms are usually mild and non-specific, but can include muscle weakness, tingling, numbness and feeling sick. 

Severe hyperkalaemia is a medical emergency that can cause fast or pounding heartbeats (palpitations), shortness of breath, chest pain and nausea (feeling sick).

Call 999 if you have these symptoms and think you may have severe hyperkalaemia.

In most healthy people, it’s unusual to get too much potassium from food alone, as the kidneys remove excess potassium and keep blood levels in a safe range.

However, potassium can build up if your kidneys are not working well.

Some heart medicines can also lead to increased potassium levels. These include:

• ACE inhibitors
• angiotensin-II receptor blockers (ARBs)
• eplerenone
• some diuretics, including spironolactone.

If you’re taking these medicines, your doctor will likely ask you to have regular blood tests to monitor your potassium levels.

You can continue to eat a balanced diet, and do not need to automatically avoid potassium-rich foods, unless your healthcare team recommends a low-potassium diet based on your blood test results.

What about foods that are low in potassium?

If you’ve been advised to eat less potassium, your healthcare team or dietitian can help you make changes that are right for you.

This includes avoiding potassium supplements, electrolyte drinks and salt substitutes containing potassium chloride.

But you do not have to stop eating all fruits and vegetables, which contain lots of other heart-healthy vitamins and minerals too.

Some fruits are relatively low in potassium, such as:

• apples
• pears
• peaches
• plums
• berries.

Lower-potassium vegetables include:

• carrots
• green beans
• cabbage
• cauliflower
• cucumber
• lettuce
• peppers
• onions
• courgettes.

You can also reduce the potassium in some vegetables by peeling, chopping, soaking and boiling them in plenty of water. This removes more potassium than steaming, microwaving or baking them.

Throw away the cooking water afterwards, as some potassium dissolves into the cooking water.

The takeaway: do potassium-rich foods lower blood pressure?

Healthy people can get all the potassium they need from a balanced diet, but most people are not eating enough.

The best place to start is by eating more whole foods, fruits and vegetables, and cutting down on processed foods and snacks that are high in salt.

Eating more potassium and less salt is proven to help lower blood pressure, especially in people who have high blood pressure.

However, if you have heart failure or kidney disease, you may have to limit your potassium intake.

What to read next...