This article is for general information only and is not medical advice. If you have a health condition, take prescribed medication or are pregnant, speak to your doctor or pharmacist before changing your supplements. Some links on this page are affiliate links, which means we may earn a small commission at no extra cost to you.
The short answer
Potassium gluconate is a well-absorbed, mild-tasting form of potassium, and a reasonable choice if you have been advised to take a supplement. It is not clearly better than the other common forms, though, and most people can get all the potassium they need from food. Potassium supplements are also not safe for everyone. If you have kidney problems, are an older adult, or take medicines for blood pressure or your heart, check with your GP or pharmacist before taking any.
What potassium does and how much you need
Potassium helps control the balance of fluids in the body and helps the heart muscle work properly. According to the NHS, adults need 3,500mg of potassium a day, and you should be able to get all of it from your daily diet. Good sources include:
- bananas
- some vegetables, such as broccoli, parsnips and Brussels sprouts
- beans and pulses
- nuts and seeds
- fish
- beef, chicken and turkey
Do you need a supplement?
Probably not, unless a doctor has told you so. Low potassium in the blood (hypokalaemia) can cause tiredness, muscle weakness, cramps and constipation, but these symptoms have many other causes. The US National Institutes of Health notes that low potassium is rarely caused by diet alone. It usually follows losses from prolonged diarrhoea or vomiting, or from medicines such as some diuretics (water tablets) and laxatives. It can only be confirmed with a blood test, so if you think your potassium is low, see your GP rather than treating it yourself.
Potassium gluconate, citrate and chloride compared
The three forms you will see most often are potassium gluconate, potassium citrate and potassium chloride. All three raise potassium levels. The main practical differences are:
- Potassium gluconate has a mild taste and is widely sold as powder and tablets. One study found that people absorb about 94% of the potassium in potassium gluconate supplements, which is similar to potassium from food. It contains less potassium by weight than the other forms (about 17%), so you need more powder for the same amount of potassium.
- Potassium citrate contains about 38% potassium by weight. Doctors also prescribe it for certain types of kidney stone.
- Potassium chloride contains about 52% potassium by weight. It is the form used in most prescription potassium and in low-sodium salt substitutes. It has a strong salty, bitter taste.
There is no good evidence that one form is better than the others for general use. Gluconate is a sensible pick if taste matters to you.
Tablets or powder?
Many potassium tablets and capsules contain no more than 99mg of potassium per serving, which is a small fraction of the 3,500mg adults need each day. Powders usually work out cheaper and let you take more per serving.
That is also the risk with powder. A heaped spoon can deliver several times the dose on the label, so always use a level measuring spoon or scales, follow the serving size on the label, and never guess. If you are not confident measuring accurately, tablets are the safer option.
How much is safe?
The NHS says that taking too much potassium can cause stomach pain, feeling sick and diarrhoea, and that taking 3,700mg or less of potassium supplements a day is unlikely to have obvious harmful effects. There is no benefit in going anywhere near that figure if you eat a normal diet.
Some people should not take potassium supplements unless a doctor has advised it:
- Older people. The NHS warns that older people may be more at risk of harm from potassium, because the kidneys become less able to remove it from the blood as we age.
- People with kidney disease.
- People taking certain medicines, including ACE inhibitors (such as ramipril), angiotensin receptor blockers (such as losartan) and potassium-sparing diuretics (such as spironolactone). These can raise potassium levels on their own.
- People already using low-sodium salt substitutes, which contain potassium chloride.
Too much potassium in the blood can affect your heart rhythm, and it may not cause any warning symptoms first.
The product we looked at
NOW Supplements Potassium Gluconate Pure Powder provides 175mg of potassium per serving, with around 413 servings per tub and no added fillers. View on Amazon.
Potassium and other minerals
Potassium does not work alone. Tap potassium on our free Mineral Interaction Wheel to see which minerals and vitamins it works with and which it may compete with. For the bigger picture, read our mineral balancing guide.
When to speak to your GP
See your GP if you have ongoing muscle weakness, cramps, tiredness or heart palpitations. They can check your potassium level with a simple blood test and tell you whether a supplement is appropriate. Call 999 if you have chest pain or a sudden, severe change in your heartbeat.