Why Sour Foods Make Your Lips Pucker

If you've ever sucked on a lime or popped a sour candy into your mouth, you've likely noticed your lips pucker in response to the food's taste. That's because sour foods contain high amounts of acid, and acidity has a direct relationship with sourness (via Mental Floss).

Sour is one of the five basic taste categories along with sweet, salty, bitter, and umami. When you eat something, your taste buds tell your brain the flavor of the food you're eating, which can determine whether or not it's safe to eat. "The purpose of our ability to distinguish tastes is survival," Dr. Trey Wilson, a dentist in New York City, told Woman's Day. "Taste buds tell your brain whether or not to swallow what's already in your mouth," he states.

Since a food's acidity can sometimes indicate whether or not that food is rotten or spoiled, the physical reaction sour foods often elicit is actually a rejection response. This reaction is meant to discourage you from eating foods that might make you sick. However, this doesn't mean that all sour foods are unsafe to eat. There are plenty of sour foods that are safe and nutritious. For example, citrus fruits, kimchi, and vinegar are all common foods that are both sour and perfectly safe to eat. 

Can sour foods hurt your mouth?

While most people will never eat enough lemons or limes to hurt their mouths, sour candy is a different story. The acids in sour candies are what makes them tasty in the first place, but they can also cause extensive damage to your mouth and tongue, especially when consumed in excess. "If you consume a lot of this highly acidic treat, you may find that the inside of your mouth feels uncomfortable or even burned," Dr. Heather Kunen, an orthodontist and the co-founder of Beam Street Dentistry, told Bustle.

The acidity of the candy can erode the enamel on your teeth and eat away at the top layer of your tongue, causing burns and blisters. These injuries can also cause the surface of your tongue to peel off, which can be quite painful. You can relieve this pain and discomfort by eating or drinking dairy products like cheese, yogurt, and milk. This will help protect your enamel and restore the pH balance in your mouth.