What’s the best way to keep your teeth from turning yellow?


The jury seems to be out on what is the best way to handle coffee teeth staining; some sites say to brush your teeth right after drinking coffee and others say to not do this because it ruins your enamel! The consensus seems to be to wait until the coffee cools and drink it through a straw which not only can look silly sometimes but ruins some of the fun of sipping steaming hot coffee on a cold day while curled up in bed.

When I was young (and drinking so much coffee that it was a miracle I was ever able to sleep) I asked a dentist whether adding milk to coffee would reduce its acidity, dilute the color, and make it overall less damaging to teeth. He seemed intrigued but didn’t have an answer for me so years later I decided to run a little experiment of my own.

Since I gave up milk a year or so ago in favor of plant-based alternatives (I found out the hard way I’m a bit lactose intolerant) I decided to go to the store and buy the available plant-based milks as well as a small container of whole milk. I also bought Tesco House Blend coffee and a pH testing kit from the naturopath internet store.



My assumption was that most of the plant-based milks would be neutral on the pH scale and that the whole-milk would be the most basic one, due to hearing that it’s good to drink milk when having heartburn because it neutralizes the acids. Following that train of thought I figured milk plus coffee combo would create a somewhat neutral beverage while the other combinations would fall on the side of acidic.

If you’re interested in the more nitty gritty details of how I set up the experiment, pls scroll down to the bottom.

Let the experiment begin!


Just in case there is some delayed reaction between coffee and its counterpart, I retested the pH after ten minutes but found no difference from the initial testing.
The strip above the mugs of coffee is the pH of each milk/milk alternative on its own without any coffee. The first line of strips underneath the coffee mugs is the pH strips after initial testing, while the second row is the pH strips after five minutes.


To my surprise, I had somehow managed to line up the milk/milk alternatives in order from most basic to acidic! I had to check twice to make sure the pH level for the soy milk was correct and that the acidity level of the whole milk was right – it completely threw my hypothesis out of the water to realize that milk is not basic, and is in fact slightly acidic (could’ve googled it but what’s the fun in that?)


Turns out adding milk to coffee can *increase* its acidity and damage to enamel, not decrease it. If you’re looking for a pH-neutral cup of coffee, soy milk is the way to go!
Please note that I’m only addressing pH and there are many other factors involved in what causes coffee to stain teeth that I am not aware of but I fully encourage others to conduct their own experiments on the matter and let me know if you find anything.

Experiment Setup:

I used 100ml of coffee and 50ml of milk/milk-substitute for my experiment, going off of the proportions I normally use when making my coffee in the morning. The coffee was set to medium strength and was still warm when conducting the experiment while the milk/milk-substitutes were still cold from the fridge (again imitating real life). I used boiling water between each use for the cup measurer to limit contamination from each liquid.

Leave a Reply