What is potassium?
Find out why we need potassium, which foods are useful sources and learn why it’s referred to as an ‘electrolyte’
Potassium is an essential mineral for the body. It’s also an electrolyte, which means it carries a small electrical charge that activates cells. This is crucial because it helps the body maintain water balance, manage blood pressure, activate muscles and send messages via the nerves. Our body is unable to make potassium, so we have to obtain it from our diet.
Check out our Vitamins and Minerals Information Hub to learn more about key nutrients – from whether you’re getting enough vitamin D to the top 10 healthiest sources of vitamin C, plus vital minerals you need in your diet.
Why do we need potassium?
One of potassium’s main roles is to help maintain normal levels of fluid inside each of our cells; sodium is what keeps levels stable on the outside of our cells. This interplay is key to many of potassium's roles, including managing blood pressure; this is because potassium helps relax blood vessels and excrete excess sodium, which appears to significantly reduce blood pressure.
Potassium, along with sodium and calcium, plays a key role in muscle contraction, which is key to heart health – together, they regulate the actions of the heart. Any imbalance may lead to heart arrhythmias or muscle contraction disorders.
Eating adequate amounts of potassium also helps manage our calcium levels. For example, it helps prevent calcium being released from our bones, or from being excreted in the urine, which way may lead to recurring kidney stones.
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The health benefits of potassium include:
- Supports fluid balance within the body
- Moves nutrients into cells and waste materials out
- Helps muscles contract
- Supports nerve transmission
- Helps support heart health
- Manages blood pressure
- Supports bone health and may reduce the risk of osteoporosis
- May minimise recurring kidney stones
How much potassium do we need?
For healthy adults aged 19-64, the UK daily recommendation for potassium is 3500mg.
Can we have too much potassium?
Healthy kidneys help to maintain normal levels of potassium by removing excess in the urine. However, in certain situations high levels may occur – this is referred to as hyperkalemia. People at risk include those with compromised kidney function or advanced kidney disease as well as those regularly taking medications that hold onto potassium in the body (this includes NSAIDs).
Symptoms of high levels of potassium include:
- weakness and fatigue
- chest pain
- heart palpitations including irregular heart rates
- nausea
- diarrhoea and stomach pain
What are the signs of a potassium deficiency?
It is rare for a deficiency to arise from diet alone, however an inadequate intake along with other factors may lead to potassium loss. These may include long-term diuretic use, laxative abuse, severe vomiting and heavy sweating. People with inflammatory bowel disease, such as Crohn’s, may also be at risk because of diarrhoea and malabsorption. One of the other relevant factors is your level of magnesium – this mineral is needed by the kidneys to reabsorb potassium and maintain normal levels in the cells.
Symptoms may include:
- Fatigue
- Muscle cramps or weakness
- Constipation
- Irregular heart rate
- Muscle paralysis
Which foods are good sources of potassium?
Potassium is found in a wide range of foods, including fruits and vegetables such as leafy greens, tomatoes, cucumbers, courgette, aubergine, pumpkins, potatoes, carrots and beans. Other useful sources include beans, dairy, meat, poultry, fish, pecan nuts and walnuts.
How you cook your food may also impact its potassium levels. As it’s water-soluble, potassium is lost during boiling, so it’s better to steam, bake or stir-fry vegetables. In addition, food processing reduces the amount of potassium in many foods and a diet high in processed foods and low in fresh fruits and vegetables may lack potassium.
Which foods are useful sources of potassium?
- Almonds
- Avocado
- Bananas
- Beans
- Cashews
- Coconut water
- Dried fruit (raisins, apricots, figs)
- Oranges
- Peanuts
- Potatoes
- Squash
- Tomatoes
- Yogurt
Recipes that contribute useful amounts of potassium
Squash & spinach fusilli with pecans
Kale & apple soup with walnuts
Courgette, pea & pesto soup
Maple pecan beans
Sweet potato & peanut curry
Red lentil & squash dhal
Banana, clementine & mango smoothie
Always speak to your GP or healthcare provider before taking a new supplement or if you are concerned about nutritional deficiencies.
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This article was reviewed on 16 November 2023 by Kerry Torrens.
Emer is a specialist dietitian who combines her love of food and science to help increase people’s awareness of a healthy lifestyle. An expert in IBS, weight loss and women’s health, she brings energy and passion to her profession and enjoys bringing the science of nutrition to life. In her ebook, IBS? Recipes For Success, Emer shares quick and easy recipes for people suffering from IBS, combining her passion for cooking with her expert knowledge. She has worked in top London teaching hospitals and balances her time between media work, private clients and NHS commitments.
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