Milking the Truth

I’ve always enjoyed “float” fizzy drinks since I was a child. If you don’t know what a “float” drink is, it’s a dark-coloured fizzy drink, usually root beer or coke, topped with some vanilla ice cream. The ice cream floats on top of the drink – thereby lending to the term “float”!

Refreshing Root Beer Float with Vanilla Ice Cream Image source

I also noticed that, if left for some time, the ice cream melts and gives the coke/root beer a kind of milky colour and texture, as seen in the picture above. The root beer has turned from black to brown. I like to compare it to adding milk to black coffee to make… well, milk coffee. Adding milk to coffee dampens its bitterness and gives a creamy finish to the taste, and so does root beer float! So a couple of years ago, I tried adding milk to coke…


Believe it or not, people are actually taking this quite seriously, and it’s startlingly interesting. This research paper is a laboratory study to determine whether adding milk to fizzy drinks can lessen the erosive potential of said fizzy drinks.

Now, for some background, fizzy drinks are VERY BAD for your teeth. They’re like the agents of destruction made with the very purpose of attacking your teeth. They are high in sugar, which leads to tooth decay. But hey, you say, what about stuff like Diet Coke? No sugar, should be good, right? Fizzy drinks in general contain phosphoric acid and citric acid, which can lead to tooth erosion. The acid demineralises tooth substance during an acid attack, so high intake of fizzy drinks will lead to worn down, ugly teeth.

According to this paper, the researchers thought that raising the drink’s calcium content by mixing it with milk could lessen the capacity for the fizzy drinks to cause erosion by suppressing demineralisation of tooth enamel.


For each drink they used 25 ml of drink with 6.25 ml UHT milk.

The pH and titratable acidity (amount of alkali required to neutralise acid, low titratable acidity means less alkali required i.e. less acidic – usually a more relevant way to measure acidity than pH) were measured.

In addition, the effects of a 60 min exposure to the drinks (+milk) upon the surface microhardness of human molar tooth substance were determined.


The researchers concluded that the addition of milk to fizzy drinks reduced their capacity to bring about erosion. Milk significantly increases their pH and decreases their titratable acidity.

They also found that adding milk lessens the reduction in surface microhardness of tooth substance following exposure to the fizzies.


We critically appraised this paper in one of our classes on Evidence-based Dentistry. So naturally I have some thoughts on this because it was taught in our course.

First of all, a lab study on pieces on teeth immersed in fizzy drinks in a test tube cannot be extrapolated to the general human oral environment. Acidic drinks tend to make you produce more saliva, which help buffer against said acids. Milk in acidic drinks may result in a reduced salivary flow so we cannot properly determine if it works in real life! Further studies need to be conducted outside the lab on human subjects in a clinical trial.

Secondly, will people accept adding milk to their coke? Do people even like it? I personally really did enjoy it. Like I said, it’s like adding milk to black coffee – gives it a certain créma! But I may be crazy, and not everyone will enjoy it. Sometimes there may even be a sedimentation reaction with coke, as shown in this picture below…

coke-milk-experiment02Image source

Doesn’t look like root beer float now, does it?

In my personal opinion, fizzy drink intake should be reduced regardless. Whether or not you add milk to it, and whether or not it is “diet” or “zero”, there is still some degree of acid erosion happening. Eliminating fizzies from your diet is the best way to stop acid erosion! Switch to alternatives such as tea & water.

HANDY TIP: Drinking fizzies is an acid attack on your teeth. Don’t brush your teeth immediately after drinking fizzies – scrubbing acids on your teeth will absolutely destroy your teeth! Wait for at least half an hour before brushing. This will give time for your saliva to buffer and neutralise the acids.

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