Last reviewed: July 2026

Electrolytes explained: sodium, potassium and magnesium in real food

Electrolytes are minerals that carry an electric charge when dissolved in body fluid, and food covers them for almost everyone. The main four are sodium, potassium, magnesium and calcium. They run nerve signalling, muscle contraction and fluid balance, which is why they get marketed so aggressively. The reality of a typical Western diet is close to the opposite of the marketing: most people take in far more sodium than the WHO's 2,000 mg daily guideline and only about half the 3,500 mg of potassium recommended alongside it. Unless you are sweating heavily for over an hour, an electrolyte drink is solving a problem you do not have.

What an electrolyte actually is

An electrolyte is a mineral that splits into charged particles when dissolved in water. Those charges are what let nerve cells fire, muscles contract and the body move fluid deliberately from one compartment to another. Sodium and chloride dominate the fluid outside your cells, potassium dominates the fluid inside them, and the pumps maintaining that gradient consume a substantial share of your resting metabolism. Magnesium and calcium act as cofactors in hundreds of reactions, including the contraction and relaxation cycle in muscle. None of this is mysterious, and none of it requires a branded powder.

Sodium: the one nearly everyone overshoots

Sodium's job is fluid balance and blood pressure regulation, and the amount required to stay alive is small, on the order of 200 to 500 mg a day. The WHO recommends staying under 2,000 mg, equivalent to about 5 g of salt. Average intakes across Europe sit closer to 3,000 to 4,000 mg. Very little of that arrives from the shaker: bread, cheese, sauces, processed meat and ready meals do the heavy lifting, which is the point made in detail in the sodium vs salt explainer. A single portion of cheddar or a couple of slices of deli meat can carry several hundred milligrams before anything is added at the table.

Potassium: the one nearly everyone undershoots

Potassium works against sodium in blood pressure regulation, and the WHO recommends at least 3,500 mg a day. Most people manage roughly half. It is not an exotic nutrient: it is abundant in unprocessed plant foods and dairy, which happen to be the categories a processed diet crowds out. The famous banana is a middling source at best.

Closing a potassium gap is unusually simple: an extra portion of potatoes, beans or leafy greens most days does it. People taking potassium-sparing diuretics or living with kidney disease are the exception and should follow medical guidance rather than general advice, because for them potassium can climb too high.

Magnesium: real deficiency exists, the hype exceeds it

Magnesium participates in over 300 enzyme reactions, and intakes below recommendations are genuinely common, particularly on diets low in whole grains, nuts and legumes. That much is fair. The leap made in supplement marketing, that magnesium fixes sleep, anxiety, cramps and fatigue in people who are not deficient, runs far ahead of the trial evidence. Food sources are dense and unglamorous: pumpkin seeds are among the richest common foods at roughly 500 mg per 100 g, dark chocolate carries around 200 mg, and oats, lentils and nuts contribute steadily across a day.

Calcium: the electrolyte that is also a building material

Calcium is an electrolyte in the fluid outside cells and the structural mineral in bone, and the body defends blood levels tightly by drawing on the skeleton when intake falls short. That is why blood calcium tells you nothing about your diet, and why intake still matters over decades. Sources and the dairy-free routes to a full target are covered in the calcium guide.

When a sports drink is actually justified

• Under about 60 minutes of exercise: water. Sweat losses at this duration do not meaningfully dent electrolyte stores in a person eating normally.
• 60 to 90 minutes and beyond, especially in heat: sodium replacement starts to matter, both for performance and to reduce the risk of dilutional hyponatraemia in people drinking a lot of plain water.
• Multi-hour endurance events: deliberate sodium and carbohydrate intake is standard practice, and this is where commercial products earn their keep.
• Illness with vomiting or diarrhoea: oral rehydration solutions are genuinely evidence-based, and are formulated quite differently from sports drinks.
• Everyday desk life: food and water. A 250 ml energy drink or flavoured electrolyte sachet mostly adds sugar and cost.

The cramp question

Exercise-associated muscle cramps are the marketing hook for the entire category, and the evidence linking them to electrolyte loss is weaker than the advertising implies. Studies comparing crampers and non-crampers in the same events often find no difference in blood electrolytes, while neuromuscular fatigue predicts cramping better. Practically, that means a cramp during a long hot session may respond to sodium, but a cramp in the gym on a Tuesday is more likely about fatigue, conditioning or unfamiliar load.

Bottom line

Eat vegetables, legumes, dairy or their fortified alternatives, nuts and seeds, and your electrolytes look after themselves. The corrections worth making for most people are downward on sodium and upward on potassium, both of which happen naturally when more of your food is cooked rather than opened. Save electrolyte products for long sweaty efforts and for illness, where they do real work.