Minerals that carry an electric charge when dissolved in water. That charge is the point: it is how your nerves fire, how your muscles contract, and how your body decides where its water goes. Sodium, potassium, chloride, calcium, magnesium, phosphate and bicarbonate are the ones that matter.
Everything the word gets attached to in marketing — energy, performance, recovery, "hydration" — is downstream of that one fact, and a lot of it is not true. Here is what electrolytes are, what they do, how you lose them, and where the category oversells.
Electrolyte — a mineral that carries a net electric charge in solution. In the body, that charge lets it conduct the signals nerves and muscles run on, and it pulls water along with it wherever it goes.
The seven, and what each one does
| electrolyte | main job | where it lives |
|---|---|---|
| Sodium | Governs fluid balance and blood pressure; drives nerve and muscle signalling | Outside cells — the main one in blood and the fluid between cells |
| Potassium | Heart rhythm, muscle contraction, nerve transmission | Inside cells — sodium's counterpart across the membrane |
| Chloride | Pairs with sodium for fluid balance; forms stomach acid | Outside cells |
| Calcium | Muscle contraction, nerve signalling, blood vessel tone, hormone release | Overwhelmingly in bone; a small, tightly controlled amount in blood |
| Magnesium | Cofactor for hundreds of enzymes; muscle and nerve function, blood glucose and pressure | Mostly in bone and inside cells |
| Phosphate | Part of ATP — the molecule cells spend as energy | Inside cells, and in bone |
| Bicarbonate | The buffer that holds blood acidity steady | Blood, managed by the kidneys |
Sodium and potassium are the pair that does most of the work you can feel. The difference in their concentration inside versus outside every cell is the battery that nerve impulses run on, and a pump in every cell membrane spends a large fraction of your resting energy keeping that difference in place. Sources: NIH Office of Dietary Supplements on sodium, potassium, magnesium; StatPearls on electrolyte physiology.
How tightly your body holds them
Very. Blood sodium sits at 135–145 mmol/L and potassium at roughly 3.6–5.5, and your kidneys defend those ranges continuously.
Two hormones do most of it. Aldosterone tells the kidneys to hold sodium and let potassium go. Vasopressin (antidiuretic hormone) tells them to hold water. Between them they adjust what leaves in urine hour by hour, which is why the amount of electrolytes you eat can vary enormously day to day and your blood levels barely move.
That regulation is the thing most electrolyte marketing quietly ignores. You are not a bucket that drains. You are a system that adjusts.
How you lose them
Sweat is the route that matters for exercise, and it is sodium-dominant. Across 696 professional athletes, sweat sodium ranged from 17 to 92 mmol/L — about 400mg to 2,100mg per litre — with the average near 46. Potassium losses in sweat are small by comparison. The range is the important part: two people doing the same session can lose sodium at five times different rates.
Urine is the everyday route, and it is the one your kidneys use to fine-tune. Diuretics, including alcohol, push more out than usual.
Vomiting and diarrhoea are the routes that get people into genuine trouble. Vomiting loses chloride and acid; diarrhoea loses potassium and bicarbonate. Both lose a lot of water fast. This is the situation oral rehydration solutions were invented for, and it is worth understanding why they work.
Why rehydration formulas have sugar in them
This is the single most useful piece of physiology in the whole subject, and it explains why "electrolyte" products are formulated the way they are.
In the wall of your small intestine there is a transporter that moves sodium and glucose across together — one of each, side by side. Water follows the sodium. Take the glucose away and the transporter idles; take the sodium away and there is nothing for the water to follow.
That pairing is the basis of oral rehydration therapy, and it keeps working even when the gut is inflamed and other absorption routes have shut down — which is why a packet of salt and sugar in clean water has saved more lives from diarrhoeal disease than almost any other intervention in medicine.
Practically: sodium with a little carbohydrate is retained better than sodium alone. A zero-sugar electrolyte drink is a legitimate choice for other reasons, but it is giving up the mechanism — what you gain and what you give up is its own article.
How much sodium you actually need — two answers that both hold
The American Heart Association recommends an upper limit of 2,300mg a day, ideally 1,500mg, and notes the average American takes in over 3,100. That guidance is correct, and it is about chronic dietary intake in a largely sedentary population, where excess sodium tracks with blood pressure.
A heavy sweater at a mid-range sweat sodium of about 1,000mg per litre, losing 1.5 litres an hour on a hot two-hour ride, has shed roughly 3,000mg of sodium — more than the daily public-health ceiling — in one session.
Those two facts are not in conflict. One is about what you eat every day. The other is about replacing what you just lost. No health authority says sweat losses should be replaced only up to 2,300mg. The honest position is that habitual intake and acute replacement are different questions, and the product category earns its keep only in the second one.
Four things the word gets attached to that are not true
"Electrolytes give you energy." They are minerals. They contain no calories and provide no fuel. They allow the machinery that uses fuel to run — different thing.
"More is better." Excess sodium is a chronic cardiovascular risk. Excess potassium can be dangerous acutely. The goal is matching what you replace to what you lost, and a person who has lost nothing needs nothing.
"You need an electrolyte drink every day." For someone who is not sweating heavily, not ill, and not on a diuretic, a normal diet supplies more sodium than they need already. The daily-drink habit is a marketing outcome, not a physiological one.
"Potassium is the important one." Sodium is what you lose in sweat and what drives fluid retention. Potassium matters — most people under-eat it, per the NIH — but it is lost in far smaller amounts and does a different job. Coconut water's reputation rests on getting this backwards; the numbers are here.
Can you have too much water?
Yes, and it is more dangerous than mild dehydration. Drink faster than your kidneys can excrete and you dilute your blood sodium — water then moves into cells, including brain cells, and they swell. StatPearls describes it as uncommon outside specific situations: endurance events with unlimited fluid, water-drinking contests, and certain medical conditions. The endurance version has a consensus statement and a body count, and we cover it properly in the long-day article. The short version: drink to thirst, and if you finish a long day heavier than you started, that is a warning, not a win.
Frequently asked questions
What are electrolytes? Minerals that carry an electric charge when dissolved — sodium, potassium, chloride, calcium, magnesium, phosphate and bicarbonate. They run nerve and muscle signalling and control where your body keeps its water.
What do electrolytes do? Conduct the electrical signals nerves and muscles use, and pull water along with them, which is how fluid balance is managed. They are not a source of energy.
Do I need electrolytes every day? Most people get more sodium than they need from food. The case for adding them is specific: heavy sweating, prolonged exercise, illness with vomiting or diarrhoea, or a diuretic.
Which electrolyte is most important? For fluid balance and sweat replacement, sodium. For heart and muscle function, potassium — and most people under-eat it. They do different jobs.
Why do electrolyte drinks have sugar? Because sodium is absorbed alongside glucose in the gut, and water follows the sodium. The pairing is what makes rehydration formulas work. Sugar-free versions give that mechanism up.
What are the symptoms of low electrolytes? Depends which one, and most mild cases have none. Serious imbalances — from prolonged vomiting, diarrhoea, kidney problems or overdrinking water — can cause confusion, weakness, cramping, irregular heartbeat or seizures, and are a medical matter rather than a drink-mix one.
Where Snake Oil fits
Built on the mechanism this page just described. 370mg of sodium — a genuine amount, not a trace — paired with 5g of carbohydrate so the transporter has both halves of what it needs. Potassium and magnesium for the jobs sodium does not do, zinc, the B lineup, vitamins C and E, and a glutamine-led amino acid blend, mixed into 16 ounces.†
It also carries 100mg of caffeine, which is worth knowing before an evening.
For a normal Tuesday, you do not need it. For a long night, a long day, or a long hot session, it is the physiology in a stick.
†These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Related reading: Best electrolyte powder: how to actually choose one · Does alcohol dehydrate you? · Best electrolyte drinks: ranked by what is actually in them