Sodium chloride

Sodium chloride is a compound made of the elements sodium and chloride. It is commonly known as table salt and in sports hydration it serves as a key electrolyte that replenishes sodium and chloride ions lost through sweat.

Fluid balance and physiological role

Salt is about 40% sodium and 60% chloride. Sodium is the main cation in extracellular fluid and is critical for maintaining water balance, transmitting nerve impulses and enabling muscles to contract and relax. Chloride is the principal anion in extracellular fluid. It partners with sodium to regulate osmotic pressure and fluid volume and helps maintain acid-base balance. Only about 500 mg of sodium per day is needed to perform these vital functions, but average dietary intakes exceed 3,000 mg because table salt is added to processed foods. Guidelines for adequate intake set 1,500 mg of sodium per day and advise limiting consumption below 2,300 mg to reduce chronic disease risk. Too much sodium can raise blood pressure, whereas too little can lead to hyponatremia. For athletes and active people, sodium chloride has an additional importance because sweat contains more sodium than other electrolytes. Sweat sodium concentration averages around 1 gram per litre (about 50 mmol) and sports drinks that supply 230–690 mg of sodium per litre (10–30 mmol) can help maintain plasma volume and prevent hyponatremia during prolonged exercise. The American College of Sports Medicine recommends athletes with high sweat rates consume 300–600 mg of sodium per hour during extended training and adjust intake according to sweat rate and environment.

Practical considerations for athletes

Most of the sodium chloride we consume comes from processed meats, bread, cheese, soups, sauces and snacks. Recreational exercisers who train for 30 to 45 minutes only need to follow general dietary guidelines because typical meals provide more sodium than is lost in sweat. Competitive athletes who train for 60 minutes or more, especially in hot or humid conditions, may need to replace salt lost in sweat. A registered dietitian can estimate an athlete’s sweat rate and sodium loss. In heavy-sweating situations like long runs or bike rides, consuming about one gram of sodium chloride per hour can help maintain hydration. Sports drinks use sodium chloride to improve taste and encourage fluid intake; some formulas combine sodium with citrate or bicarbonate to reduce gastrointestinal discomfort. Despite its importance, high salt intake can contribute to high blood pressure over time, so daily intake should remain within recommended limits when training loads are low.

Sodium chloride is therefore more than just seasoning. It supplies sodium and chloride ions that support nerve conduction, muscle function and fluid balance. In sports drinks it replaces salts lost in sweat and enhances fluid absorption. Athletes should adjust their salt intake to their sweat rate and environmental demands while keeping overall dietary sodium in check.

Related Terms: sodium citrate, sodium bicarbonate, potassium chloride, sweat rate, exercise-associated hyponatremia (EAH)