Sodium

Sodium is an essential electrolyte and the major positively charged mineral in the fluid outside your cells. It helps maintain fluid balance, transmits nerve impulses and supports muscle contraction.

Why sodium is key to rehydration

During exercise and heat exposure, sweat carries away water and sodium. Because sodium regulates blood volume and pressure, losing too much can lead to cramps, dizziness or hyponatremia. Sports drinks include sodium to replace these losses and to stimulate thirst and fluid retention. Research on post‑exercise rehydration shows that beverages with at least 40 millimoles of sodium per litre help maintain blood osmolality and suppress urine output better than drinks with lower sodium levels. By keeping sodium levels up, a sports drink encourages you to drink more and keeps the fluid in your body rather than excreting it. Sodium also helps the gut absorb glucose and water when small amounts of sugar are present. For most people, the sodium in sports drinks is not a significant source of dietary salt because serving sizes are modest and intake occurs during heavy sweating.

Salt in your bottle

Most sports drinks contain between 20 and 50 millimoles of sodium per litre (roughly 460‑1150 milligrams). Drinks aimed at rapid rehydration after intense exercise, such as oral rehydration solutions, may contain closer to 60–90 millimoles to quickly restore sodium balance. Lower‑sodium products around 20 millimoles are designed for casual hydration and may be better tolerated in cooler conditions. Athletes with high sweat rates or those exercising for more than an hour in hot environments may benefit from more concentrated electrolyte powders or salted snacks alongside fluids. Consuming only plain water during long events can dilute blood sodium and increase the risk of hyponatremia, so a balanced sodium intake is crucial.

Sodium is the backbone of sports drink formulations. By replacing the salt lost in sweat and promoting fluid retention, it helps athletes maintain performance and avoid the pitfalls of dehydration.

Related Terms: electrolyte, potassium, chloride, magnesium, palatability