What are electrolytes and what do they do in your body?

This article was reviewed by Dr Mark Atkinson, M.B.B.S., FRSPH, for medical and scientific accuracy before publication.

What are electrolytes? | Which electrolytes are there? | How do they work? | What do they do in your body? | Sodium–potassium pump | Electrolytes vs water | How to get electrolytes?

Key Takeaways

• Electrolytes are minerals that carry an electrical charge.

• They support fluid balance, nerve signals, muscle function and pH regulation.

• Electrolytes work as part of a system, not as isolated nutrients with a single function.

• They can only function when dissolved in water, where they form charged particles (ions).

• Proper hydration depends on both water and electrolytes, not water alone.

• Sodium and potassium play a key role in directing where water is distributed in the body.

 

What are electrolytes?

Electrolytes are minerals that dissolve in bodily fluids to form electrically charged particles, known as ions. These ions play an important role in processes such as nerve conduction, muscle function, fluid balance and pH regulation in the body. (1)

Which electrolytes are there?

The most important electrolytes in the human body are:

• Sodium (Na⁺)

• Potassium (K⁺)

• Chloride (Cl⁻)

• Calcium (Ca²⁺)

• Magnesium (Mg²⁺)

• Bicarbonate (HCO₃⁻)

• Phosphate (PO₄³⁻)

Together, these minerals help regulate the internal balance of the body.

How do electrolytes work?

Electrolytes function in bodily fluids as electrically charged particles (ions).

Thanks to their electrical charge, the ions can create small voltage differences between the inside and outside of cells. These voltage differences form the basis for important processes in the body, such as:

• nerve impulses

• muscle contraction

• the distribution of fluid

• maintaining a stable pH balance

Electrolytes therefore do not function as standalone substances with a single specific task, but as part of a coherent system in which fluid, minerals and electrical signals are continuously aligned.

Ions in water

Electrolytes can only do their work when dissolved in water. In that form, they break down into positively and negatively charged particles: ions.

The body is largely made up of water. That water is found in different locations:

• inside the cells

• outside the cells, for example in the blood

In this watery environment, ions are able to move. A well-known example is the distribution of two electrolytes:

• Sodium (Na⁺) is found mainly outside the cell

• Potassium (K⁺) is found mainly inside the cell

Their movement is driven by differences in concentration and electrical charge.

What do electrolytes do in your body?

Each electrolyte, each mineral, has a different function in the body. The table below provides an overview of the main roles. (2)

Electrolyte	Main role in the body
Sodium (Na⁺)	Regulates fluid outside the cells, supports nerve conduction and blood pressure regulation.
Potassium (K⁺)	Regulates fluid inside cells, essential for muscle function and heart rhythm.
Chloride (Cl⁻)	Works with sodium to maintain fluid balance and plays a role in acid-base balance.
Calcium (Ca²⁺)	Essential for muscle contraction, nerve signals and bone structure.
Magnesium (Mg²⁺)	Supports muscle relaxation, nerve function and enzyme activity.
Bicarbonate (HCO₃⁻)	The main buffer for pH regulation in the blood.
Phosphate (PO₄³⁻)	Part of energy production (ATP), bone structure and pH buffering.

So, electrolytes play an important role in a range of processes, including:

• the distribution of fluid in the body

• electrical signals between nerve cells

• muscle contraction

• regulation of acidity (pH)

The body's ability to keep internal processes stable is called homeostasis. The following sections explain how electrolytes support these functions.

1. Fluid balance

An important function of electrolytes is regulating the distribution of water in the body.

Water naturally moves towards areas where more dissolved substances are present. This process is called osmosis.

In physiology, this principle is often summarised as: "Water follows sodium."

This means sodium plays an important role in determining where water is located in the body.

• Sodium mainly influences fluid outside the cells

• Potassium plays an important role in fluid balance inside the cells

When the concentration of these minerals changes, water can shift between different parts of the body.

2. Nerves and muscles

Nerve cells communicate via electrical signals. These signals are generated when ions move through small channels in the cell membrane.

During a nerve impulse, the following occurs, for example:

• sodium flows into the cell

• potassium then flows back out

This movement temporarily changes the electrical voltage of the cell. The signal can then travel along the nerve.

In muscles, calcium additionally plays an important role in activating muscle contraction. Magnesium, in turn, helps with muscle relaxation.

3. pH balance

The body monitors the acidity of the blood very precisely. Bicarbonate and phosphate in particular help with this. These substances can absorb small changes in acidity.

As a result, the pH of the blood remains stable. This is important for many processes in the body, such as enzyme activity and metabolism.

The sodium–potassium pump

An important mechanism in cells is the sodium–potassium pump. This is a transport protein in the cell membrane that actively moves sodium and potassium using energy (ATP). In each cycle, the following occurs:

• 3 sodium ions are pumped out

• 2 potassium ions are brought in

This maintains the difference between sodium outside the cell and potassium inside the cell. (3) Through this mechanism, the body is able to:

• transmit electrical signals between nerve cells

• enable muscles to contract

• keep the distribution of electrolytes around cells stable

Without this pump, the differences between sodium and potassium would gradually disappear, causing nerve and muscle cells to function poorly. For more information about a possible imbalance, read our article about Electrolyte Deficiency.

 

Electrolytes vs water

Water and electrolytes fulfil different roles in the body. Water forms the medium in which processes take place. Sodium, in particular, plays an important role in determining where water is in the body.

Hydration is therefore not just about how much water a person drinks, but also about the balance between water and electrolytes.

How do electrolytes help keep water in the right place?

Electrolytes influence how water is distributed between different parts of the body.

Because sodium is found mainly outside the cells, it plays an important role in retaining fluid in the bloodstream and in tissues.

Potassium plays a greater role inside the cells. Together, these differences ensure that water is found in the right places in the body.

Why 'more water' doesn't always mean better hydration

The way water is distributed in the body largely determines how well the body is hydrated. Drinking more water increases total fluid intake, but does not guarantee optimal hydration.

Hydration does not simply mean that sufficient fluid is present, but also that:

• the ratio between water and electrolytes remains balanced

• fluid is in the right place within the body

Therefore:

Hydration ≠ fluid intake alone
Hydration = fluid + electrolyte balance

How do you get electrolytes?

Electrolytes are obtained through food and drink. You can read more about this in the article "How to get Electrolytes? Food that contains Electrolytes". After absorption through the digestive tract, they are distributed throughout the bodily fluids. The kidneys and hormonal systems then help to keep concentrations stable.

Conclusion

Electrolytes are minerals that function in the body as electrically charged particles. They are essential for processes such as fluid balance, nerve conduction, and muscle function. They determine how much fluid your body contains, and above all, where that fluid is located and how effectively it is used.

Without a proper balance between electrolytes such as sodium and potassium, important processes in the body cannot function optimally. That is why hydration is about fluid intake plus the right ratio between water and electrolytes.

How many electrolytes you need on average is usually specified per mineral. An overview of these guidelines can be found in the article "How many electrolytes do you need per day?".

Medical Disclaimer

This article is intended as a general explanation of electrolytes and their role in the body. It is not a substitute for medical advice, diagnosis or treatment. For questions about health, symptoms or possible disturbances of electrolyte balance, it is advisable to consult a doctor or other qualified healthcare professional.

References

1) MedlinePlus – Electrolytes (definition + functions)
https://medlineplus.gov/ency/article/002350.htm

2) MedlinePlus – Electrolyte Panel (main functions of Na, K, Cl, HCO₃⁻)
https://medlineplus.gov/lab-tests/electrolyte-panel/

3) NCBI – Physiology, Sodium Potassium Pump
https://www.ncbi.nlm.nih.gov/books/NBK537088/