What are electrolytes and why do I need them?

Profile picture of Iona Bell
Specialist Dietitian, Cromwell Hospital
18 August 2022
Next review due August 2025

Electrolytes are minerals that are essential for your body to function. The main electrolytes are sodium, potassium and chloride as well as magnesium, calcium, phosphate and bicarbonates.

An adult drinking water from a bottle

Why are electrolytes important?

Electrolytes are essential for basic life functioning. This includes maintaining fluid balance and helping muscles and nerves to work properly. Your body works to keep electrolytes in a very fine balance. If the level of electrolytes in your body becomes too high or too low, it can disrupt normal body functions. In severe cases, this can even lead to life-threatening complications. Symptoms of electrolyte imbalance include:

  • muscle weakness and cramping
  • headaches
  • confusion
  • irregular heartbeat
  • feeling sick

What is a good source of electrolytes?

You get electrolytes from foods and fluids in your diet. Good sources of electrolytes include the following:

  • Sodium and chloride are mostly found in your diet as salt (sodium chloride). Foods high in salt include bacon, olives, prawns, cheese, pickles and anchovies.
  • Foods that have sodium include bananas, apricots, spinach and potatoes. It is also found in meat, fish and cereals.
  • Good sources of calcium include milk (and fortified milk alternatives), cheese, curly kale and bread made with fortified flour. Phosphate is found in dairy foods, meats, fish, nuts and beans.
  • Good sources of magnesium include nuts, greens, whole grains and dry beans.

You should be able to get all the electrolytes you need through a healthy, varied diet.

What causes an electrolyte imbalance?

Your body is very good at keeping electrolytes within narrow limits, and your kidneys play a vital role in this. But sometimes, levels can become too high or too low. There can be several reasons for this. You may have an underlying health condition that affects your electrolyte levels. These conditions include kidney disease, heart failure and diabetes. Certain medications can cause an imbalance too.

You lose electrolytes when you sweat. So, your electrolyte level may also drop too low if you’re sweating more than usual (such as during an intensive or long exercise session). Vomiting or diarrhoea can cause your electrolyte levels to drop too.

When might you need more electrolytes?

Most people should get all the electrolytes they need from a healthy, varied diet. But there are some circumstances when taking additional electrolytes may help.

This includes if you’re doing strenuous exercise, especially if it’s for longer than an hour. It’s recommended to drink water before, during and after you exercise to keep hydrated. However, if you’re exercising for longer than an hour, it’s important that you also replace the sodium that you lose through sweating. Sports drinks that contain electrolytes, including sodium and potassium, could be a convenient way of replacing lost electrolytes.

An electrolyte supplement may also be useful if you’ve had vomiting or diarrhoea. A doctor or pharmacist may advise you to have oral rehydration therapy, which contain electrolytes such as sodium and potassium. These are available as solutions or powders that you mix with water. They work to make sure you get the right amount to maintain a safe level.

Remember, most of the time, our bodies keep our electrolyte levels tightly controlled and there’s no need to supplement them. But it helps to be aware of what can happen when your electrolytes are too low. You can then give your body a helping hand to restore your electrolyte balance.

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Profile picture of Iona Bell
Iona Bell
Specialist Dietitian, Cromwell Hospital

    • Shrimanker I, Bhattarai S. Electrolytes. StatPearls Publishing, last updated 26 July 2021
    • Electrolyte and fluid balance. Oxford handbook of nutrition and dietetics (3 ed, online). Oxford Medicine Online., published online April 2020
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    • Vitamins and minerals. British Nutrition Foundation., last reviewed June 2021
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    • Orrù S, Imperlini E, Nigro E, et al. Role of functional beverages on sport performance and recovery. Nutrients. 2018;10(10):1470. Doi:10.3390/nu10101470
    • Fluids and electrolytes. NICE British National Formulary., last updated 4 April 2022

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