Have you ever made the mistake of taking a giant swig of orange juice with your breakfast just after brushing your teeth? If you have, you likely remember how terrible it tasted. You’ll be happy to know you aren’t the only one who has experienced this. It’s so common, in fact, that researchers decided to look into why exactly this occurs.

One ingredient in toothpaste, sodium lauryl sulfate, or SLS, is likely the culprit, according to scientists. SLS is a surfactant and is added to toothpaste as a sudsing agent. It’s the reason your toothpaste gets frothy in your mouth and makes it easy to spread around across and in between your teeth. Surfactants like this are often added to soaps, shampoos and detergents as well. Consumer research shows that people like seeing foaming bubbles when they use products meant for cleaning -- it makes us feel like the product is doing its job!