Understanding the effects of carbonation

Carbonated drinks are a huge part of many people’s daily lives, and the fizzy sensation in our mouths is all part of that fascination. When I have asked why people drink them, they say they find carbonated water more refreshing and convenient.

But do we really know what this process is, and how does a liquid become fizzy, and is this fizz good or bad for us?

Have you ever asked questions about carbonated water?

What is carbonation?

The carbonation process is chemistry in as much as gas is forced into a solution, and it's a phenomenon that really does raise several questions. This process influences taste and texture, and therefore the appeal of carbonated drinks.

The combining of water and CO2 creates carbonic acid and changes the pH (remember school chemistry, with the litmus paper testing for acidity and alkalinity of items).

Water is pH neutral at 7. However, carbonated water sits between 5 and 6.5, which is an increase in acidity.

The history of carbonation

Carbonation goes back to the 18th century when a gentleman called Joseph Priestley discovered a method for introducing carbon dioxide into water. This really was a huge innovation of its time, and it went into early production, and these were the exceedingly early mineral waters. 

Joseph Priestley had no idea that this carbonation process would take off and that it would become a global sensation. And, he had no idea that this process would have an impact on human health, behaviour, and the environment.

Because the carbonation process in drinks has become a global phenomenon, there is now more research that investigates the pros and cons.

Health implications have been identified, and we're going to discuss these.

The presence of carbon dioxide

Let’s look at the key ingredient of a carbonated drink. Carbon dioxide is the essential ingredient of carbonated beverages. The carbon dioxide itself creates the fizz that people often associate with these drinks.

The presence of carbon dioxide must be considered with its role in our physiology, and this gets ignored when we are just looking at it as something that is within a liquid, as opposed to what is its function.

Water is obviously the foundation of carbonated drinks.

Natural fresh waters are high in minerals, dependent on what they have flowed through (rocks, chalk, peat, glaciers), and these can give a background flavour or consistency. Some people are more sensitive to this than others. And, importantly, these natural waters are not fizzy!

An interesting factor of natural water is that it is neutral; its pH level will not create harm, it creates life and balance, whereas if we carbonate water, we are changing a fundamental part of its structure and its purpose, and the carbonation role increases the acidity of this liquid.

So, what is the purpose of carbonation? It doesn’t act as a preservative, it merely acts as something to add sensation to an experience of drinking a liquid. So, why has it become so essential and part of the public expectation of carbonated drinks?

Most traditional fizzy drinks have additional sugars added and other additives such as flavours, colours, and sweeteners. Their healthiness has become confusing. For example, a standard can of cola can contain 140 calories plus, and this high calorie content adds another negative drawback of carbonated drinks. Not only are you increasing your pH acidity to the liquid that you're ingesting, but you are also adding more calories to the liquid, increasing the calorie burden of your overall day-to-day living.  

People often overlook how quickly those calories will add up. Added sweeteners appear to have no calorific burden, that’s a fact, but the physiological pathway is the same as sugar, so there's still a likelihood of having the glycaemic triggers that would happen with sugar.

Digestion

Carbonated water may increase ghrelin, the hormone which makes us feel hungry. A study has shown a correlation between drinking carbonated water and eating more calories. So, whilst a fizzy drink may quench our thirst. There is a likelihood that we will be reaching for more snacks.

Fizzy drinks are known to bloat and extend the stomach, causing a higher risk of acid reflux and weakening of the pyloric and oesophageal valves.

Some studies have also found that they can damage the gut bacterial balance, leading to various issues such as IBS, bloating, abdominal pain, and excessive burping.

Bones and dental health

Fizzy flavoured waters can have detrimental effects on teeth, as most of these contain citric acid, which gives the flavour. Studies have shown that this will raise the acidity of the fluid and lead to dental erosion. Bear in mind that carbonated water already has an increase in acidity, so the addition of citric acid doubles down on the erosion risk.

Whilst research is limited, it has shown that, for some individuals, excessive use of these flavoured mineral waters can lead to a buffering action, leaching minerals from bones, to bring the pH down. Although the pH changes are only small, over an extended period, the effects are heightened.

References:

• Mathur K, Agrawal RK, Nagpure S, Deshpande D (2020). Effect of artificial sweeteners on insulin resistance among type-2 diabetes mellitus patients. J Family Med Prim Care, 28;9(1):69-71.