Supplement
Electrolytes
Mineral · sodium / potassium / magnesium
Sodium, potassium, magnesium and chloride regulate fluid balance, nerves and muscles. Electrolyte drinks have a real, well-supported benefit: they keep fluid in the body better than water when you have sweated a lot or are ill. Many promises around cramps, energy and focus, however, go beyond what the studies show.
In short
Electrolytes are dissolved minerals, mainly sodium, potassium, chloride and magnesium. Solutions of sodium and sugar retain fluid measurably better than water, in children with diarrhea modern rehydration solutions reduced the need for infusions, and the EU has approved two health claims for carbohydrate-electrolyte drinks during prolonged endurance exercise. For muscle cramps in competition, by contrast, large observational studies show no link with electrolyte levels. Most people in Germany consume more sodium than necessary, so electrolyte powders bring little in everyday life without heavy sweating. The biggest risk in endurance sport is not too little salt, but drinking too much.
What it is
Electrolytes are minerals that are present in water as charged particles. Sodium and chloride mainly determine the amount of fluid outside the cells, potassium the amount inside. Magnesium is involved in muscle and nerve function; for magnesium the EU permits, among other things, the claim that it contributes to electrolyte balance.
There are three groups on the market. Classic rehydration solutions from the pharmacy combine sodium with glucose. Sports drinks supply carbohydrates plus some sodium. And sugar-free electrolyte powders, popular with low-carb diets and fasting, often contain a lot of sodium, plus potassium and magnesium.
How it is supposed to work
The core is well understood physiology. In the small intestine, sodium is absorbed together with glucose, and water follows. That is why rehydration solutions work in diarrhea, and why sodium-containing drinks keep fluid in the body longer. Anyone who sweats heavily loses mainly sodium in addition to water. How much varies greatly: sweat rate and sodium content in sweat vary with intensity, heat, heat acclimatization, fitness, body size and sex.
Beyond that, a lot is attributed to electrolytes: protection against cramps, more energy, a clear head, fewer complaints when starting a ketogenic diet. With keto, the reasoning is that cutting carbohydrates leads to more sodium and water being excreted. A review of the typical starting symptoms sees a physiological rationale for this, but found no clinical studies demonstrating the effect of electrolytes.
Who it is worthwhile for
The American College of Sports Medicine advises avoiding a water loss of more than 2 % of body weight during exercise, as well as large shifts in electrolytes. Because people sweat so differently, the society recommends individual drinking plans. The simplest way to estimate your own sweat loss is to weigh yourself before and after a session. According to the position stand, drinks with electrolytes and carbohydrates can offer advantages over water under certain circumstances, that is, mainly during long, sweaty exertion. For short sessions without significant sweat loss or a normal office day, such an advantage has not been shown.
What is well supported
Fluid retention is well supported. In a study with 72 men and 13 drinks, a rehydration solution kept significantly more fluid in the body than water after 2 hours; the index was 1.54. Milk performed similarly, whereas a regular sports drink was no better than water. In children with acute diarrhea, modern, less concentrated rehydration solutions less often required an infusion than the older standard solution, according to a Cochrane review of 8 studies. Stool volume and vomiting also decreased, without low sodium levels becoming more frequent.
For sport, the EU has approved two claims: carbohydrate-electrolyte solutions contribute to the maintenance of endurance performance during prolonged endurance exercise and enhance the absorption of water during physical exercise. The conditions are narrow: 80 to 350 kcal per liter from carbohydrates and 460 to 1,150 mg of sodium per liter. A pure electrolyte powder without carbohydrates does not meet them.
What the studies show
Which drink is retained longest
Seventy-two healthy men each drank 1 L of one of 13 drinks on different days, after which urine was collected for 4 hours. After water, 1,337 g of urine was produced, after the rehydration solution only 1,038 g. Sports drink, coffee, tea, cola, beer and juice did not differ from water.
Cramps at the Ironman
Blood values and body weight were measured in 210 triathletes before and after an Ironman. The 43 athletes with cramps did not differ from the others in electrolytes and fluid loss. The cramps could be predicted by a faster pace and previous cramp episodes.
Salt in the ultramarathon
During a 161 km run at up to 39 °C, 20 finishers recorded everything they ate and drank. How much sodium they took in had nothing to do with whether they developed cramps, nausea or a low sodium level. The authors therefore consider the widespread belief in salt capsules as protection to be unsupported.
Water or electrolytes after sweating
Ten men ran downhill in the heat until they had lost 2 % of their body weight and then drank water or an electrolyte solution. The researchers measured the electrical stimulation frequency at which a calf cramp could be triggered. After water this threshold fell, so the muscles became more prone to cramping; after the electrolyte solution it rose. This is a laboratory finding with artificially induced cramps, but a clear indication that rehydrating with plain water after heavy sweating is not ideal.
Where the data stop
The best-known advertising line, that electrolytes prevent cramps, does not hold up in competition. Neither at the Ironman nor in the marathon or ultramarathon did runners with cramps differ from runners without in sodium, potassium or fluid loss. In the marathon, those with cramps instead had more muscle damage; at the Ironman, it was the faster athletes. According to Cochrane, magnesium did not noticeably help with nocturnal calf cramps in older people either.
We found no study on more energy or focus from electrolytes in everyday life. And electrolytes alone, without carbohydrates, did not consistently improve fluid retention compared with water in a study with 19 adults. The keto flu is a plausible but untested area of use.
Status, approval and legal
In Germany, electrolyte powders and sports drinks are foods or food supplements. The BfR considers adding sodium to food supplements not useful, because most people already consume enough, and for drinks intended to compensate for increased sodium losses proposes 460 to 1,150 mg of sodium per liter. For magnesium, the BfR recommends at most 250 mg per daily dose of a food supplement, for potassium 500 mg. EFSA considers 2.0 g of sodium per day safe and adequate for adults; the D-A-CH societies estimate 1,500 mg. These are reference values, not intake recommendations. Drinking electrolytes is not doping; infusions of more than 100 ml within 12 hours outside medical treatment, by contrast, are on the WADA list.
Safety
The most important risk in endurance sport is a low sodium level from drinking too much. A review names excessive drinking beyond thirst as the most common cause, and a case report shows that even more than 6,500 mg of sodium did not protect a runner who drank 9.2 to 10.6 L of water. In Germany sodium tends to be consumed in excess: adult men take in a median of 2,940 to 3,415 mg per day, and with high blood pressure additional salt is unfavorable. Potassium can cause dangerously high blood levels in kidney disease and with certain blood pressure medications. Magnesium above 250 mg extra per day more easily leads to diarrhea; the BfR recommends splitting the amount.
BK-Score Supported, with caveats
| Human evidence | 7 | |
|---|---|---|
| Mechanism | 9 | |
| Safety data | 8 | |
| Hype gap | 5 | |
| Track record of use | 9 |
Sodium-glucose cotransport for fluid absorption is established human physiology, not a marketing story – but the benefit is tied to a condition. Systematic reviews on rehydration show the advantage over plain water with relevant sweat loss, that is, heat or endurance exercise lasting more than 60 to 90 minutes. For normally active people without such loss, there is no evidence of an additional benefit over eating and drinking. Both hyponatremia in endurance athletes and the risks with impaired kidney function are well documented.
The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)
Frequently asked questions about electrolytes
When do you need electrolytes?
Mainly with heavy sweating over a longer period, for example during long endurance sessions in the heat, and with diarrhea or vomiting. In normal everyday life, the usual diet usually covers sodium needs more than adequately.
Do electrolytes help against muscle cramps?
In competition, large observational studies show no link between cramps and electrolyte levels. Cramps were more closely linked to pace, muscle fatigue and previous cramps. After heavy sweating, however, rehydrating with electrolytes instead of plain water appears to reduce cramp susceptibility in the laboratory.
Are electrolyte drinks better than water?
Rehydration solutions with sodium and sugar keep fluid in the body longer than water. A regular sports drink was no better than water in one study. For everyday life without major fluid loss, water is enough.
Do you need electrolytes on keto?
There is a plausible rationale, because more sodium and water are excreted when starting a ketogenic diet. Clinical studies demonstrating the benefit of electrolytes against the keto flu are, however, still lacking.
Can you take too many electrolytes?
Yes. Too much sodium strains blood pressure, too much potassium is dangerous in kidney disease, and too much magnesium causes diarrhea. For food supplements, the BfR proposes at most 250 mg of magnesium and 500 mg of potassium per daily dose.
Does salt protect against hyponatremia in a marathon?
Not reliably. The most important cause is drinking too much beyond thirst. In ultramarathon running, sodium intake was not related to who developed a low sodium level.
Related
- Works together withMagnesium
- Same categoryIron
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- Same categoryShilajit
- Also for energy and muscleCreatine monohydrate
- Also for muscle and sportWhey protein
- Same goal: More energyExogenous ketones / ketone esters
- Same goal: More energyCaffeine
- Same goal: More energyMCT oil
- Same goal: Muscle buildingTart cherry
- Same goal: Muscle buildingBeta-alanine
- Same goal: Muscle buildingLeucine
Sources
- Maughan et al., Am J Clin Nutr 2016 – Beverage Hydration Index
- Hahn et al., Cochrane 2002 – reduced-osmolarity rehydration solution
- Schwellnus et al., Br J Sports Med 2011 – cramps in 210 Ironman triathletes
- Hoffman et al., Sports Med Open 2015 – sodium in ultramarathon running
- Lau et al., BMJ Open Sport Exerc Med 2019 – water, electrolytes and cramp threshold
- Hew-Butler et al., Front Med 2017 – exercise-associated hyponatremia
- Garrison et al., Cochrane 2020 – magnesium for muscle cramps
- Skartun et al., Front Nutr 2025 – symptoms when starting keto
- BfR – proposed maximum levels for sodium
- Regulation (EU) No 432/2012 – permitted health claims
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-30.