It’s 7:45 a.m. on a Monday morning and you’re running late. You brush your teeth, remembering to spend a full two minutes on them, then head to the kitchen for a quick breakfast before you miss your 8 a.m. train. As you’re buttering your bagel, you take a swig of your orange juice and your taste buds are hit with the all-too-familiar, terrible mix of toothpaste and orange juice. All of the sudden, your train doesn’t matter and all you can think about is the dreadful cocktail of flavors swirling around your mouth.

It’s no secret that toothpaste makes everything you eat after it taste awful, but it’s more than just the minty taste lingering on your teeth that causes the torment. The real culprits? Sodium Laureth Sulfate (SLES) and Sodium Lauryl Sulfate (SLS), the ingredients in toothpaste that make it foam when they come in contact with water. When these agents are present, your toothpaste’s surface area is multiplied, filling your entire mouth. Incidentally, versions of these same chemicals are found in paint and laundry detergent. They make a little bit of anything go a long way!

Along with foaming, these chemicals alter how our taste buds function. First, they suppress the receptors that pick up sweetness, preventing us from enjoying sweet flavors. Second, they break up the phospholipids present on the surface of our tongue. Phospholipids are fatty molecules that help prevent our receptors from being overwhelmed by bitter tastes. Since our toothpaste is breaking these down, the bitter taste is not only allowed, but also intensified.

So, that orange juice that just assaulted your taste buds was less sweet and more bitter thanks to your toothpaste. But have no fear, there is a way to end the torment! Go for an SLES/SLS-free toothpaste next time you buy. Although it won’t foam as much as a regular toothpaste, it will clean your teeth just as well and that toothpaste and orange juice combination won’t ruin your morning commute.

If you have further questions, ask Dr. Levine for a recommendation on a non-foaming toothpaste. And if you missed your 8 a.m. train due to your terrible toothpaste and orange juice debacle, tell your boss it was Sodium Laureth Sulfate and Sodium Lauryl Sulfate’s fault!