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There’s nothing like a freshly squeezed, tangy glass of OJ to go with your morning meal. But if you’ve just brushed your teeth, you may find that beverage tastes -- less than delicious. So, why does toothpaste affect the taste of orange juice and other sweet breakfast -- or midnight -- snacks? We’ll tell you.

What is SLS?

All food is made of smaller substances-- even food that grows in the ground or on trees. Some of these substances nourish us, while others are connected to color or taste. And like any substance, the substances in food interact in sometimes curious and interesting ways. Take, for instance, the not-so-pleasant taste that comes from stuffing pretty much any food in your mouth after you’ve just given your pearly whites a good scrub. What in the world is going on there? 

Sure, the strong minty flavor is probably a part of the problem, as one might expect, but it actually goes much deeper than that. You see, most tubes of toothpaste contain sodium lauryl sulfate (SLS), which is responsible for making your favorite toothpaste foam up in your mouth -- it’s also the culprit behind everything tasting so terribly bad after you brush. 

Sodium lauryl sulfate (SLS) is one of the ingredients you’ll find listed on many of your cosmetic products, like your bottle of shampoo and tube of toothpaste. However, unless you’re a chemist, chances are you don’t have the slightest clue as to what it is.

SLS is what's commonly known as a “surfactant.” This means it lowers the surface tension between ingredients, which is why it’s used as a cleansing and foaming agent to keep your teeth squeaky clean. But aside from helping your favorite tube of toothpaste clean your teeth, surfactants also affect your tastebuds -- in fact, surfactants like SLS affect your tastebuds in two ways:

First, it suppresses your receptors that pick up the sweet taste in drinks and food. This is why some foods tend to taste a little off if you’ve recently given your teeth a good scrub. The second way surfactants affect your tastebuds is it enhances bitter flavors, so sour drinks and food taste, especially bitter -- yum

Do Sulfates Like SLS Cause Canker Sores?

SLS is what gives you that oh-so-clean bubbly, foamy feeling when you’re brushing your teeth that manufacturers know makes you feel like your mouth is cleaner. That foamy feeling from SLS might feel good, but the truth is that it actually strips away the protective lining of the mouth. In fact, believe it or not, SLS is rated as a high hazard for irritation and a moderate hazard for organ toxicity by the Environmental Working Group’s Cosmetic Database. It’s pretty strong stuff -- hence why it’s found in many household cleaning solutions. Yikes! 

In a recent study, researchers found that individuals who stopped using toothpaste containing SLS reduced their canker sores over a three-month period from an average of a whopping 14.3 ulcers down to 5.1 ulcers. Other studies have echoed these results as well. Furthermore, a study from 2012 highlighted the fact that for those who already had a pesky canker sore present, using SLS-free kinds of toothpaste decreased the pain and even the duration of the ulcers. 

As for why this harmful surfactant causes these painful sores, experts believe that SLS irritates the soft and super-sensitive tissue inside your mouth and gums, removing protective layers and making them much more susceptible to canker sores. 

Remember, a susceptible mouth is a vulnerable mouth, and bacteria love to cling onto teeth in vulnerable mouths, which can open Pandora’s box to a plethora of health issues. 

It’s true -- your mouth is the gateway to your overall health. A vulnerable mouth increases the risk of bacterial infection in your bloodstream, which can affect you negatively in more ways than one. 

Whether you suffer from canker sores or not, switching your toothpaste to a brand that’s SLS-free is an excellent choice for preventive care. But buyer beware -- some sneaky manufactures are hiding SLS in their ingredients under different names. 

Here are some of the ingredients to watch out for:

  • Monododecyl ester sodium salt sulfuric acid
  • Akyposal SDS
  • Sodium Dodecyl Sulfate
  • Sodium dodecyl sulphate
  • Sodium salt sulfuric acid
  • Monododecyl ester
  • Monododecyl ester
  • Sulfuric acid monododecyl ester sodium salt
  • Sulfuric acid
  • Sodium salt
  • A13-00356
  • Aquarex Methyl

Okay, but do a toothpaste’s ingredients really actually matter if I’m not swallowing it?

So you may be wondering why avoiding toxic toothpaste ingredients like SLS is so incredibly important when toothpaste isn’t in your mouth for very long you certainly don’t swallow it. (Well, at least you shouldn’t!)

But here’s the deal: The mouth-body connection is very real, and as we mentioned, poor oral health can contribute to many unwanted (and totally preventable) health conditions, such as heart disease, diabetes, and even osteoporosis. 

As a result, having a happy, healthy mouth is of the utmost importance, and anything we put into our mouths -- no matter how briefly -- can greatly affect our oral and overall health.

As we just touched on a little earlier, our mouths are lined with protective mucous membranes, which can become inflamed, irritated, and infected with toxic ingredients like SLS. Our mouths can also absorb those nasty chemicals into the bloodstream, while certain ingredients can disrupt the natural balance of flora (both “bad” and “good” bacteria) in our mouths that aids in maintaining our oral health. This imbalance can even affect your gut microbiome.

Here are some other harmful ingredients to stay away from: 


What is it: Triclosan is another harsh ingredient commonly found in toothpaste… and pesticides…

Why is it harmful: There have been numerous animal studies that have linked triclosan to endocrine (hormone) disruption. In fact, this ingredient is so dangerous that the FDA has actually banned the use of triclosan in soap and body wash -- but it’s still in toothpaste, for some odd reason. 

Artificial Coloring

What is it: Artificial toothpaste colors are used to make commercial toothpaste fun and aesthetically pleasing. 

Why it’s harmful: Believe it or not, artificial coloring chemicals have been linked to hyperactivity and ADHD in kids. In fact, according to one study, artificial food colors have a negative effect on children, even if they haven’t been diagnosed with ADHD. We don’t know about you, but we’re much more worried about how effective our toothpaste is -- not how sparkly and blue it is. 


What are they: Parabens are nasty chemicals commonly used as preservatives to extend the shelf life of the toothpaste. 

Why it’s harmful: The FDA is actually still reviewing and evaluating published studies surrounding the safety of parabens. Known to disrupt hormones, these harsh chemicals are used in most beauty products and even in most grocery items. Even if the levels in these individual products are deemed “safe,” the accumulation in our bodies could cause some serious problems, including a possible increase in the risk of breast cancer.  

Propylene Glycol 

What is it: Propylene glycol is a synthetic chemical compound commonly used as a surfactant.

Why it’s harmful: Although the FDA classifies this harsh compound as safe, propylene glycol is known to irritate the skin, eyes, lungs, and mucous membranes. Case in point: Propylene glycol is the first ingredient used in antifreeze, paint, and detergent solvents. Although we don’t want our favorite tube of toothpaste freezing on us, we definitely don’t want to be scrubbing our teeth with this stuff! Based on research showing that propylene glycol was toxic in rats after long-term use, experts advised that the intake of propylene glycol be limited, especially in children.  

A Final Word 

So, what is SLS, and why does it make things taste bad, you ask?

SLS is a surfactant that basically enhances bitter tastes and inhibits sweet ones, making everything taste bad. Additionally, SLS has been linked to poor oral health, which can lead to many health issues down the road. Taking care of your mouth by avoiding harmful chemicals like SLS is your first line of defense in preventive care because your mouth is essentially the gateway to your overall health. Take care of yourself and kick totally-preventable illnesses to the curb by reaching for a great toothpaste from an amazing company like Twice.

For a cleaner paste with a better taste, backed by science, research, and the dental industry, you need to brush those pearly whites with Twice!