Potassium: what it does and how much you need
Potassium helps the kidneys, heart, muscles and nerves work, and helps balance fluids in the body. Adults need an adequate intake of 3,400 milligrams for men and 2,600 milligrams for women, and no upper limit has been set. Most supplements carry 99 milligrams or less, because larger potassium chloride doses in pill form have been linked to gut damage. People with kidney problems or on some blood pressure medicines should check with a doctor first.
General information, not medical advice. Check with a doctor or pharmacist before taking a supplement, especially if you are pregnant or breastfeeding, take any medicine, or are under 18.
In the UK
In the UK, adults need 3,500 milligrams a day, and the NHS says up to 3,700 milligrams a day from supplements is unlikely to cause harm. Most supplements carry 99 milligrams or less, because larger potassium chloride doses in pill form have been linked to gut damage. People with kidney problems or on some blood pressure medicines should check with a doctor first.
How much you need and the upper limit
| US (NIH) | UK (NHS) | |
|---|---|---|
| Adults need | An adequate intake of 3,400 milligrams for men and 2,600 milligrams for women | 3,500 milligrams a day |
| Upper limit | No upper limit has been set for potassium in healthy people. | Up to 3,700 milligrams a day from supplements |
The UK figure is the amount the NHS says is unlikely to cause harm. Figures are for adults.
Cautions
- Most supplements carry 99 milligrams or less, because larger potassium chloride doses in pill form have been linked to gut damage. People with kidney problems or on some blood pressure medicines should check with a doctor first.
Food sources
- Dried apricots
- Lentils and beans
- Potatoes
- Bananas
- Spinach
- Milk and yogurt
Dose questions
Quick answers
- What does potassium do?
- Potassium helps the kidneys, heart, muscles and nerves work, and helps balance fluids in the body.
- How much potassium do adults need?
- Adults need an adequate intake of 3,400 milligrams for men and 2,600 milligrams for women (US, NIH). In the UK: 3,500 milligrams a day (NHS).
- What is the upper limit for potassium?
- US: No upper limit has been set for potassium in healthy people. UK (NHS): up to 3,700 milligrams a day from supplements is unlikely to cause harm.
- Which foods have potassium?
- Dried apricots, lentils and beans, potatoes, bananas, spinach, milk and yogurt.
- What should I watch out for with potassium?
- Most supplements carry 99 milligrams or less, because larger potassium chloride doses in pill form have been linked to gut damage. People with kidney problems or on some blood pressure medicines should check with a doctor first.
Sources
- NIH Office of Dietary Supplements fact sheet
https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/ - NHS vitamins and minerals guidance
https://www.nhs.uk/conditions/vitamins-and-minerals/others/
Ask Supplement Check yourself
Type a vitamin, mineral or supplement, a dose, or a product name, and get the daily need, the upper limit and any cautions. Open Supplement Check, free, no sign-up.
In Claude or any app that takes MCP connectors, add https://goodturn-mcp.pages.dev/supplementcheck/mcp and ask: “Is a 99 mg potassium supplement safe?”