What's the deal with electrolyte drinks — do you need them to stay hydrated?

A classic 20-ounce bottle of lemon-lime Gatorade contains nearly one-eighth teaspoons of salt and 80 milligrams of potassium — electrolytes "to help replace what you sweat out," the product's ads say .

Powerade, another top sports drink brand with flavors like Peach Pucker and Grape Shocker, boasts "50% more electrolytes" than Gatorade .

U.S. consumers spend more than $10 billion a year on sports drinks, according to Beverage Industry , a trade publication. That doesn't include electrolyte powders, foil-packed sticks from brands such as Liquid I.V. and Prime that people are swishing into their water bottles all summer.

The category has expanded well beyond its athlete niche into wellness products for daily living, industry analysts say. And now scores of online influencers promo