Sparkling water is one of my favorite beverages and I am admittedly a bit of a brand snob. La Croix is my favorite - we've been buying it for years. And more recently I've tried Waterloo, which I like as well. Then my husband came home and told me an anecdotal account of a woman (friend of a friend) whose extensive tooth decay was deemed a result of her La Croix habit. "La Croix causes tooth decay," he told me. "You should look into it." What?!
But apparently I'm behind the eight ball on this topic. The debate was raging in 2016 after The Atlantic published an article called 'The Sad Truth About Seltzer,' which cited a 2007 UK study that concluded sparkling water is erosive on teeth. Researchers soaked extracted molars in peach flavored fizzy water for thirty minutes and found changes in the appearance of the enamel suggestive of erosion. Since then, however, and fortunately for me, most dentists agree that there are far worse beverages to consume than sparkling water for the health of one's teeth.
The cause for concern though is the acidity of sparkling water and other popular drinks. Both acid and sugar will cause decay if either is allowed to sit on a tooth's surface for long. In fact, sugar is harmful to teeth because it gets converted to acid. This occurs via bacteria that naturally reside in our oral cavity and use sugar as an energy source. They produce ATP through the conversion of carbohydrates to lactic acid using a metabolic process called fermentation. FYI It's identical to what our own muscle cells do in the absence of oxygen!
The bacterial colonies retain the acid they produce for up to two hours on a tooth's surface before one's saliva can neutralize it, resulting in decay.
How does prolonged acid exposure cause decay?
Our teeth, and in particular the enamel that provides the hard surface coat, are over ninety percent mineral. Mineral is a composite of charged molecules that exist in an organized matrix. Hydroxyapatite is the mineral that makes up our teeth and it consists of calcium (Ca++), phosphate (PO4---), and hydroxyl (OH-) ions. These molecules form a dense and compact lattice structure that is held together by the attraction of opposite charges.
Hydroxyapatite. The organized matrix is formed through the interaction of positively charge calcium ions and negatively charged oxygen atoms.
Hydroxyapatite is able to withstand great temperature fluctuations, physical force, and exposure to a variety of chemicals. But acid is its Achilles heal. You see acid is essentially a bath of positive hydrogen ions (H+) that interfere with the charged interactions that hold hydroxyapatite together.
The definition of an acid is a substance that releases H+ into water-based solutions like saliva. When acid sits against our teeth, the free hydrogen ions released attract the negative ions of our enamel - the phosphates and hydroxyls - literally pulling them from the mineral matrix into the oral cavity and creating pockets in the tooth's surface. This is called tooth demineralization or decay. If the decay becomes severe enough, the cavity in the enamel must be filled to prevent damage of the inner tooth and nerve.
The positive hydrogen ions (H+) released by an acid will attract and remove the negative ions that form the hard mineral of our tooth enamel, causing pits and decay in a tooth's surface.
Have you ever wondered what pH is? It's simply the measure of how many free hydrogen ions are in a solution. The higher the H+ concentration ([H+]), the lower the pH and the stronger the acid. A standard pH scale is measured from 0 to 14 with 7 being neutral. A pH below 7 is acidic while anything above it is basic or alkaline. Basic solutions do the opposite of acids; they remove free protons from solution thereby decreasing the overall H+ concentration.
So back to the acidic nature of seltzer water...
While I struggled to find the pH of any of La Croix's waters listed online, I was shocked to learn that most brands of seltzer - even the unflavored varieties - have a pH of 3.5 to 5.5.
Acidic.
The first reason for this is chemical. To make water effervescent, carbon dioxide (CO2) gas is added to water (H2O). But a small portion of these two molecules chemically combine to form a new molecule called carbonic acid, H2CO3. H2CO3 will release some of its hydrogen ions, increasing the H+ concentration and decreasing the pH of the water.
Flavored sparkling waters tend to be even more acidic because they have acids added to them for flavoring. Citric acid, found naturally in citrus fruits like oranges, lemons, limes, and grapefruits, imparts a pleasing tangy flavor to beverages. Malic acid, which occurs in apples, pears, and cherries, is used to enhance a beverage's intrinsic flavor - or as La Croix calls it the 'natural essence'. Addition of an acid will further increase the H+ concentration in a beverage and lower its pH.
So what beverages are not acidic?
Interestingly enough, the answer that I have arrived at is NONE. Ninety-nine point nine percent of the beverages we all regularly enjoy are acidic. So I'm not quite sure why sparkling water was recently at the forefront of concern.
An article by the American Dental Association lists hundreds of popular U.S. beverages and the pHs are all below 7.
Natural fruit juice like grape, apple, and orange has a pH near 3. Vitamin Waters and Gatorades are at or below 3. While Starbucks coffee is a 5.1 most teas are below pH 3. Even V8 vegetable juice has a pH of 4.2. Then there's soda pop: Coca-Cola, Mountain Dew, 7-Up, Dr. Pepper, cream soda. Most of these are in the 2s. Beer and wine range from pH 3-5. And if you've jumped on the kombucha wagon, the acetic acid of that beverage brings the pH down to a 2.5. But here's the real shocker.
Even a bottle of still Dasani water has a pH of 5.0.
So, are there any alkaline options? Maybe.
The two least acidic options are milk (pH 6.5 to 6.7), which is just slightly acidic due to its natural lactic acid content, and municipal tap water. Municipal water ranges from pH 6.5 to 8.5 depending on the ground system. Birmingham, Alabama is recorded as having tap water with a pH of 7.2... so you could always move there.
Fortunately for our teeth, drinking acidic beverages doesn't seem to matter too much. First, saliva acts as a natural buffer against acids. A buffer is a solution that will quickly absorb or release hydrogen ions as needed to maintain a desirable pH. Saliva is effective at keeping our mouth's pH in the range of 6.2 to 7.6 regardless of what we drink.
Second, we already know that for acid to cause erosion it must sit on our teeths' surface for a long while. The 2007 UK study that sparked debate over the erosive potential of seltzer incubated molars for thirty minutes. Thirty minutes. I don't hold La Croix in my mouth for any length of time let alone thirty minutes. In fact beverages barely touch my teeth. They go through my puckered lips and down my throat.
So no. Seltzer and acidic beverages are not the issue. The real culprit of tooth erosion is sugar. And by sugar I mean fermentable carbohydrates: starch, glucose, lactose, maltose, sucrose. Whether you eat a gooey, sweet gummy bear or a banana, drink a coca-cola or a glass of milk, the sugars in your diet will cause tooth decay if they aren't promptly removed from your teeth. And this is why:
Remember those fermenting flora that call your mouth home? They live happily on your teeth in sticky mini-societies called biofilms. As the bacteria metabolize sugar and generate H+, they do so within the biofilm and directly against your enamel. And it is here that hydrogen ions become trapped; hidden from the neutralizing potential of saliva and primed to cause demineralization.
Just this month, the highly reputable medical journal, The Lancet, published a two part series in which over a dozen dentists and public health experts call to attention a global rise in oral disease due to increased sugar consumption. "Sugar is the causative agent for dental decay," says Robert Weyant, one of the study authors and a dental public health expert at the University of Pittsburgh. "Basically, without sugar, you won't develop decay."
So what about the woman whose story inspired this post? The one whose tooth decay was apparently caused by La Croix and not sugar? I asked my husband for more details after my research gave me cause for doubt. "Yeah," he said. "Apparently she drank thirty cans a day." What?! That's 360 ounces (or 45 cups) a day. She was lucky to have tooth decay and not water intoxication.
Okay. So, I suppose the lesson here is if you're going to drink La Croix (which I will happily continue to do), do so in moderation.
Don't hold it in your mouth for thirty minutes.
And it's probably also best not to use it as mouth wash.