New Delhi, May 23 -- IN 1965 SCIENTISTS at the University of Florida mixed an unusual cocktail of water, sugar and salt for the college's American football players. The drink tasted like urine, but the Florida Gators downed it anyway. With lemon juice added for flavour, Gatorade-as the drink was called-was designed to replenish the minerals lost through sweating during hard training sessions in the southern heat. The team reckoned it also boosted their stamina on game day.

Gatorade was an early electrolyte drink, a category of beverage now popular among athletes, gymgoers and schoolchildren. Influencers on social media hawk the stuff as a way for ordinary people to achieve "superior" hydration. But who actually needs it?

Electrolytes ar...