Electrolytes: what are they and do I need to replenish them?

Why are electrolytes important?

Electrolytes are important because they help our body in the following ways:

1. Balance fluids in our bodies
2. Maintain the pH level (acid/alkaline) of our blood within the optimal range (7.35-7.45)
3. Move nutrients in and waste materials out of our cells
4. Activate muscles to contract and help the heart beat
5. Transmit nerve signals
6. Help with blood clotting
7. Build new tissue

Next, discover how much water should you drink a day, how to stay hydrated on a run and 15 foods for staying hydrated.

What are the main electrolytes?

There are seven significant electrolytes that are essential to the body; these include:

Sodium

Most of the salt (sodium) in our diet comes from processed, commercially prepared foods – although fish, seafood and even eggs are natural sources.

Read more about the sodium in your diet.

Potassium

Most fruit and vegetables contain potassium, especially bananas, avocado, leafy greens and dried fruit, as well as nuts and coconut water.

Read more about why potassium is important.

Calcium

Dairy foods are well-known for their calcium content, with semi-hard cheese varieties such as gouda and edam especially high. You can also try yogurt, canned fish with bones (such as sardines), calcium-set tofu as well as nuts. We also need adequate amounts of vitamin D to ensure we absorb calcium appropriately.

Read more about calcium and why it's so important.

Chloride

Table salt is approximately 40% sodium and 60% chloride, so when you add table salt to a recipe or season your meal, you'll be adding both of these electrolytes.

Magnesium

Useful food sources include green leafy vegetables, nuts, seeds, wholegrains and dark chocolate.

Discover more about the role magnesium plays in our diet.

Phosphate

These are the salts of the mineral phosphorus, and can be found in food like dairy, red meat, poultry, seafood and legumes.

Bicarbonate

This is naturally produced by the body, so you don't need to worry about including it in your diet. Our kidneys regulate levels, although after a bout of diarrhoea, there may be a loss.

Do I need to replace electrolytes?

Your body works hard to maintain your electrolyte balance and keep it within a pretty tight range. However, levels may get out of balance if you’ve suffered from a period of prolonged vomiting or diarrhoea, have a fever or have been sweating excessively following strenuous activity.

After diarrhoea and vomiting

Ongoing episodes of loose or watery stools, as well as persistent vomiting, may cause dehydration and electrolyte imbalance. Oral rehydration solutions often include sodium, potassium and magnesium; these are useful because while water may replace lost fluids, it won't restore your electrolyte levels.

After strenuous sport

Electrolytes can be lost through sweat during and after exercise. Sport drinks help replenish these electrolytes and, because they contain carbs, also restore energy lost during training. As you rehydrate, avoid caffeinated, alcoholic or excessively sugary drinks, as these are likely to increase dehydration.

What other conditions may cause low levels of electrolytes?

Other causes might include not drinking or eating enough, for example in conditions like anorexia and bulimia, or conversely eating and drinking to excess – including drinking too much alcohol. Chronic respiratory conditions like emphysema or certain medications (including steroids, diuretics or laxatives) can also affect electrolyte levels.

How would I know if my electrolyte levels are out of balance?

Your daily need for electrolytes depends on a number of factors, including your age, activity levels, the amount and type of fluids you drink and the climate you live in. Signs that might suggest an imbalance include muscle spasms or weakness, irregular heart rate, tiredness, confusion and a change in blood pressure.

Should your GP have concerns about your electrolyte levels, they may suggest an electrolyte test. This is often done as part of a routine blood test or renal profile.

How can I replenish my electrolyte levels?

Eating a balanced diet, which includes a wide variety of fruit and vegetables, and staying well hydrated is key to replenishing and maintaining electrolyte levels. Here are some other things you can do to maintain balance:

1. Don’t add salt to your food; instead, flavour foods using herbs and spices
2. Avoid highly physical activity during the hottest times of the day. If you are training for a sports event, such as a marathon, you will need to pay particular attention to how you hydrate. This is because both fluid and electrolytes are lost in sweat. That said, you don’t want to overdo the fluids, because consuming too many drinks, especially those with a diuretic action, may flush electrolytes out of the body
3. Finally, if you are on medication, including over-the-counter products, and you suspect they may be causing an electrolyte imbalance, speak to your GP or pharmacist

Try these electrolyte-boosting recipes

We’ve hand-picked a selection of recipes that include useful ingredients to support your electrolyte levels. Helpful foods include spinach, kale, avocado, strawberries, eggs, soya and lean meats.

Watermelon & strawberry slushie
Spinach smoothie
Curried spinach & lentil soup
Avocado & black bean eggs
Mexican beans & avocado toast
Blueberry & banana power smoothie
Banana & tahini porridge
Halloumi, carrot & orange salad
Chilli & orange salmon with watercress, new potatoes & wasabi mayo
5-a-day chicken with kale & pistachio pesto

Enjoyed this? Now read:

What to eat for a workout
10 best foods to help you stay hydrated
How to stay hydrated
How much water should you drink every day?
A guide to the IBS diet

This article was reviewed on 12 September 2023 by registered nutritionist Kerry Torrens.

Kerry Torrens BSc. (Hons) PgCert MBANT is a registered nutritionist with a post-graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including Good Food.

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