Potassium: function, foods, deficiency and supplements

Find out all about potassium, including what it does, how much you need, where to find it and who might need to supplement their diet


What is potassium and what does it do?

Potassium is essential for a number of important functions in the body including maintaining a healthy nervous system and regulating blood pressure.1 A healthy, balanced diet should provide all the potassium you need – fresh fruit and vegetables are the best sources – although studies show around one in five UK women aren’t getting enough.2

Function of potassium

What does potassium do in the body?

Potassium is needed for:

  • maintenance of normal blood pressure
  • healthy muscle function
  • supporting the nervous system3
The mineral works as an electrolyte, conducting nerve signals throughout the body to generate muscle contractions, including those in the heart and gut.4 Research shows that a diet rich in potassium may help protect against osteoporosis by significantly lowering the amount of calcium lost via the kidneys,5 while the results of over 30 studies found that potassium may be beneficial for the prevention and control of high blood pressure and stroke.6

How much potassium do I need?

All adults need 3,500mg of potassium a day.7 We cannot produce potassium in the body so this amount has to come from our food. You can take a supplement, but be aware that too much potassium (more than 3,700mg a day) could trigger stomach ache and diarrhoea.8

Do children need potassium?

  • 1-3 years old – 800mg a day
  • 4-6 – 1,100mg a day
  • 7-10 – 2,000mg a day
  • 11-14 – 3,100mg a day
  • 15-18 – 3,500mg a day9

Potassium foods

Which foods are the best sources of potassium?

Many foods contain potassium, but plant sources tend to be the most plentiful. Plant foods high in potassium include:10
  • fruit, especially bananas
  • white beans
  • potatoes
  • spinach
  • avocados
  • tomatoes
  • nuts and seeds
You can also find potassium in animal foods, such as beef, chicken, turkey and fish or shellfish.11

Potassium deficiency

What are the symptoms of potassium deficiency?

A potassium deficiency is called hypokaelemia. Symptoms can be vague, but include:12,13
  • confusion
  • fatigue
  • cramps
  • muscle weakness
  • constipation
  • heart failure, in extreme cases
Low potassium levels can be caused by severe diarrhoea, vomiting or diuretics – tablets that ease water retention.14

What happens if I consume too much potassium?

Healthy people don’t need to worry about high potassium levels, as the kidneys remove excess amounts via urine. But those with kidney problems, diabetes, older people and people taking blood pressure medications may be at risk.15 Too much potassium in the blood can trigger nausea, vomiting, tingling or numbness, palpitations and chest pain.16 Seek medical help immediately if you have any of these symptoms.

Potassium supplements

When should I take potassium supplements?

You can get all the potassium you need from eating a balanced diet. You should only take a potassium supplement if you’re advised to do so by your GP.17 Potassium supplements are sometimes recommended for people with high blood pressure, along with a low-sodium diet,18 but – again – this should only be done under medical supervision.

Should children take a potassium supplement?

No. According to the World Health Organisation, children can get all the potassium they need from a healthy balanced diet.19

Should women take a potassium supplement during pregnancy?

It is not necessary or advisable for pregnant women to take potassium supplements. If you think you could have a deficiency, speak to your doctor.

What are the potential benefits of potassium?

Potassium is vital for maintaining blood pressure and, in turn, a healthy heart. A 2011 US study on nearly 13,000 people reported that those who had a higher intake of potassium were less likely to develop heart disease, or die from the condition.20 Research by the University of Surrey shows that a diet rich in potassium can help lower the risk of osteoporosis, by reducing the breakdown and reabsorption of bone. This improved bone strength, warding off the bone-thinning condition.21 Shop Potassium Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies. Written by Beth Gibbons on December 5, 2018 Reviewed by dietitian and nutritionist Azmina Govindji on December 13, 2018

1. European Commission. EU Register on nutrition and health claims. Available from: http://ec.europa.eu/food/safety/labelling_nutrition/claims/register/public/?event=register.home
2. British Nutrition Foundation. Potassium. Available from: https://www.nutrition.org.uk/nutritionscience/nutrients-food-and-ingredients/minerals-and-trace-elements.html?limit=1&start=7
3. As Source 1
4. Kristeen Cherney. Healthline. What is potassium? Available from: https://www.healthline.com/health/potassium
5. Lambert H, et al. The effect of supplementation with alkaline potassium salts on bone metabolism: a meta-analysis. Available from: https://link.springer.com/article/10.1007%2Fs00198-014-3006-9
6. Aburto NJ, et al. Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. Available from: https://www.ncbi.nlm.nih.gov/pubmed/23558164
7. NHS. Potassium. Available from: https://www.nhs.uk/conditions/vitamins-and-minerals/others/
8. As above
9. Public Health England. Government Dietary Recommendations. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/618167/government_dietary_recommendations.pdf
10. Taylor Jones. Healthline. 14 Healthy Foods That Are High in Potassium. Available from: https://www.healthline.com/nutrition/high-potassium-foods#section9
11. As Source 7
12. Megan Ware. Medical News Today. Everything you need to know about potassium. Available from: https://www.medicalnewstoday.com/articles/287212.php
13. As Source 2
14. Mayo Clinic. Low potassium (hypokaelemia). Available from: https://www.mayoclinic.org/symptoms/low-potassium/basics/causes/sym-20050632
15. Carmella Wint, Kristeen Cherney. Healthline. High Potassium. https://www.healthline.com/health/high-potassium-hyperkalemia
16. As above and Source 11
17. As Source 6
18. Weaver CM. Potassium and health. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3650509/
19. World Health Organisation. Potassium intake for adults and children. Available from: https://www.who.int/nutrition/publications/guidelines/potassium_intake_printversion.pdf
20. Yang Q, et al. Sodium and potassium intake and mortality among US adults: prospective data from the Third National Health and Nutrition Examination Survey. Available from: https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/1106080

21. Science Daily. Potassium salts aid bone health, limit osteoporosis risk, new research finds. Available from: https://www.sciencedaily.com/releases/2015/01/150114115340.htm