In Turkey, going out for an ayran is actually a summer afternoon treat. It quenches the thirst, in part because the yogurt has a cooling effect, but also thanks to the salt. Adding salt to the mixture is the quickest way to get extra sodium -- a key nutrient that’s depleted when you’re dehydrated. (The same reason you see so much sodium in sports drinks in the US.)
This isn’t some new phenomenon either: the Turkish have been drinking ayran for thousands of years. It’s said to have been discovered when the Gokturks, Turkey’s ancient ancestors, first started making yogurt. The problem was that the yogurt was just a tinge too bitter. The solution -- diluting it with some water -- led to its drinkable form. Today, ayran is found far beyond Turkey too -- some version of the drink can be found in nearly a dozen countries, spanning the Middle East and Caucasus. Yogurt is an indispensable ingredient in much of Turkey’s cooking -- it’s found in everything from dipping sauces for meats to appetizers to, of course, the ayran.
Salty drinkable yogurt isn’t the only option. There’s also the sweet lassi -- an Indian yogurt beverage that’s quick and inexpensive to make. Because of its convenience, sweet lassi is a staple in Indian households, particularly in the Punjab region, which is credited with creating the drink to quench the thirst of dehydrated farmers. Like the ayran, the lassi is a mix of yogurt and water, but instead of salt, a sweetener is added in. Sometimes, it’s sugar, but there are more complicated versions, too, like rosewater or mango. To help the drink stay cool, it’s normally served in a clay flask, because no one (especially not people living and working in the desert) want to drink warm milk on 100 degree days.