The history of electrolytes: how a supplement became popular

Electrolyte powders now sit beside protein tubs and coffee pods in many British kitchens. Our editorial team traced how a set of ideas born in cholera wards and physiology laboratories turned into one of the best-selling supplement categories of the decade.

From cholera wards to physiology labs

The story of electrolyte drinks begins not in sport but in medicine, and partly in Britain. During the cholera epidemic of 1832, the Leith physician Thomas Latta reported in The Lancet that injecting salt solutions into the veins of dying patients could produce dramatic, if often temporary, recoveries. It was one of the earliest demonstrations that replacing lost water and salts could save lives.

Half a century later, the London physiologist Sydney Ringer made a famous accidental discovery. Frog hearts kept beating in his laboratory solution only when it was made with tap water rather than distilled water. The difference turned out to be the calcium and other minerals in London's water supply, and his later work defined the importance of sodium, potassium and calcium in heart and muscle function.

Ringer's solution, and later variants, became standard in hospitals. The basic idea, that the body depends on precise concentrations of charged minerals called electrolytes, underpins everything from intravenous drips to the sports drinks on supermarket shelves.

Electrolytes in this context mainly means sodium, potassium, chloride, magnesium and calcium. Sweat contains mostly sodium and chloride, with smaller amounts of the others, which is why sodium dominates the conversation about hydration in sport.

Oral rehydration: a quiet revolution

In the 1960s, researchers working in Bangladesh and India showed that a simple solution of salt and glucose taken by mouth could treat cholera and other severe diarrhoeal illness. Glucose helps the gut absorb sodium, and water follows. The approach was cheap, safe and could be given by families rather than doctors.

The Lancet described oral rehydration therapy in a 1978 editorial as potentially one of the most important medical advances of the century. It went on to save millions of lives, and the principle of pairing sodium with carbohydrate shaped the composition of sports drinks that followed.

In Britain, a different glucose drink was already on the shelves. A Newcastle pharmacist created a glucose beverage in the late 1920s to help people recovering from illness. For decades it was associated with sickbeds rather than sport, before being repositioned as an energy and sports drink in the 1980s with the help of high-profile athletes.

These two paths, medical rehydration and commercial glucose drinks, converged as exercise scientists began studying what athletes actually needed during long events.

The birth of the sports drink

The modern sports drink is usually traced to 1965 at the University of Florida, where kidney specialist Robert Cade and colleagues were asked why the American football team wilted in the heat. They found players were losing large amounts of fluid and sodium in sweat and created a drink containing water, sodium, potassium and sugar.

The team's success that season became part of the product's legend, and the drink was commercialised. Over the following decades, sports drinks became a global industry, promoted through sponsorship and backed by a growing body of laboratory research, much of it funded by the companies themselves.

Position stands from the American College of Sports Medicine, including the 2007 statement on exercise and fluid replacement led by Sawka, helped establish evidence-based guidance: drink to prevent excessive dehydration during prolonged exercise, and include sodium when sweating heavily or exercising for long periods.

At the same time, critics argued that the industry had blurred the line between science and marketing. A 2012 BMJ investigation by Cohen questioned the quality of evidence behind many claims and the influence of commercial funding on hydration advice.

The other side: drinking too much

As the message "stay hydrated" spread, a new problem appeared among recreational marathon runners: exercise-associated hyponatraemia, a dangerous fall in blood sodium caused mainly by drinking more fluid than the body loses. Almond and colleagues studied Boston Marathon runners and found that a notable proportion had low sodium at the finish, with weight gain during the race being a key risk factor.

Severe hyponatraemia can cause confusion, seizures and death. The international consensus on exercise-associated hyponatraemia, led by Hew-Butler and colleagues, now emphasises drinking to thirst as a sensible default for most people and warns against fixed, high fluid targets.

This was a turning point in public messaging. Electrolytes in a drink can modestly slow the fall in sodium, but they cannot fully protect someone who drinks far beyond their needs.

• Symptoms of hyponatraemia include headache, nausea, bloating, confusion and swelling of hands and feet.
• Weight gain during a long event is a warning sign of overdrinking.
• Anyone confused or collapsed after endurance exercise needs urgent medical assessment.

Why electrolytes are trending again

In recent years, electrolyte powders, effervescent tablets and high-sodium sachets have become a lifestyle product, promoted for everyday energy, "better hydration" at the desk and hangover recovery. Many are low in sugar, which appeals to those following low-carbohydrate diets.

For endurance athletes training for several hours in the heat, salty sweaters and those with very high sweat rates, electrolyte products have a genuine place. For someone sitting at a desk and eating normal meals, which already contain plenty of salt in the typical UK diet, the benefit is far less clear.

Some high-sodium products contain amounts that add significantly to daily salt intake. People with high blood pressure, kidney disease or heart failure should check with a clinician before using them regularly.

Editorial conclusions

Electrolyte replacement grew from life-saving medical treatments, through laboratory physiology, into a global sports and wellness market.

The science behind sodium and fluid replacement during long, hot exercise is solid. The leap to everyday use for people who are not sweating heavily is driven more by marketing than by evidence.

Overdrinking remains a real risk, and drinking to thirst is a sensible starting point for most people.

For further reading, see our articles on sweat testing, sodium needs in endurance sport and choosing between isotonic and hypotonic drinks.

References

1. Ringer S. A further contribution regarding the influence of the different constituents of the blood on the contraction of the heart. J Physiol. 1883;4(1):29–42.
2. Sawka MN, Burke LM, Eichner ER, et al. American College of Sports Medicine position stand. Exercise and fluid replacement. Med Sci Sports Exerc. 2007;39(2):377–390.
3. Almond CSD, Shin AY, Fortescue EB, et al. Hyponatremia among runners in the Boston Marathon. N Engl J Med. 2005;352(15):1550–1556.
4. Hew-Butler T, Rosner MH, Fowkes-Godek S, et al. Statement of the Third International Exercise-Associated Hyponatremia Consensus Development Conference, Carlsbad, California, 2015. Clin J Sport Med. 2015;25(4):303–320.
5. Cohen D. The truth about sports drinks. BMJ. 2012;345:e4737.
6. Water with sugar and salt [editorial]. Lancet. 1978;2(8084):300–301.