What electrolytes are, and what they actually do
Electrolytes are charged minerals, sodium, potassium, magnesium, chloride, that run hydration, nerve signaling, and muscle contraction. What they do and how much you need.
What people ask us next.
- What are electrolytes, in plain terms?
- Charged minerals dissolved in your body fluid, mainly sodium, potassium, chloride, magnesium, and calcium (IOM 2005). The charge lets them conduct electrical signals, which is how nerves fire and muscles contract. Sodium also controls how much water stays in your blood. They are essential, but a normal diet plus working kidneys keeps them balanced without a supplement.
- What do electrolytes do?
- Three core jobs: control fluid balance (mostly sodium), fire nerve impulses and contract muscle (sodium and potassium across cell membranes), and support clotting and muscle relaxation (calcium and magnesium). Depletion shows up as cramps, weakness, and fatigue, and in severe cases as dangerous heart rhythm changes.
- Do I need an electrolyte supplement?
- Usually not. A sedentary person eating a normal diet maintains electrolyte balance automatically through the kidneys. You need to actively replace electrolytes during prolonged sweating (endurance exercise, hot-weather work), vomiting or diarrhea, or low-carb and fasting states. Sodium is the priority in all of those.
- Which electrolyte do most people under-replace?
- Sodium, during heavy sweat loss. People often drink plain water, which replaces fluid but dilutes sodium further, the opposite of what is needed and, taken to an extreme in endurance events, a cause of hyponatremia. Potassium is chronically low in Western diets generally, but during acute sweat loss sodium is the one to prioritize.
- Can I make my own electrolyte drink?
- Yes, and it is far cheaper. About 1/4 teaspoon of table salt (~500 mg sodium) plus a pinch of potassium-chloride salt substitute in water delivers the same active electrolytes as a branded stick pack. Our electrolyte powder ranking shows that DIY costs roughly a fifth of branded stick packs per mg of sodium, with an identical profile.
- Are sports drinks a good electrolyte source?
- They contain electrolytes but are built around sugar and are usually low in sodium relative to what heavy sweaters need. A standard sports drink has ~110 mg sodium per cup, well below the ~500-1000 mg per serving in dedicated electrolyte products. For sweat replacement, a higher-sodium powder or a DIY mix is more targeted; for casual hydration, plain water and food are enough.
Every claim, cited.
- [01]Institute of Medicine. 2005. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. National Academies Press. Roles and requirements of the major electrolytes.
- [02]NIH Office of Dietary Supplements. Potassium Fact Sheet for Health Professionals. Potassium intake gaps and physiological role.
- [03]Sawka MN, Burke LM, Eichner ER, et al. 2007. American College of Sports Medicine position stand: exercise and fluid replacement. Med Sci Sports Exerc 39(2):377-390. Sodium replacement during prolonged sweating.
- [04]Hew-Butler T, Rosner MH, Fowkes-Godek S, et al. 2015. Statement of the Third International Exercise-Associated Hyponatremia Consensus. Clin J Sport Med 25(4):303-320. Overdrinking plain water and dilutional hyponatremia.
The Larderlab Team builds evidence-led frameworks for eating, lifting, and stocking a kitchen. We cite every claim. We publish the spreadsheet when possible. We buy what we review at retail price. When new data lands, we revise with a dated note.
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