How do sports drinks and gels affect your teeth?

by Alan McCubbin


Cyclists often spend a lot of time putting sugary drinks, gels, bars and other goodies into their mouth, especially during a ride. Because of that, there’s often concern both from riders and dentists about the impact these foods have on the teeth of cyclists.

So do regular users of sports nutrition products actually have greater risk of teeth problems than other people? Should we be concerned about tooth erosion and decay? Are all on-bike options the same or are some better than others? And what can you do to minimise your risk?

The first thing we need to understand is what we actually mean by tooth erosion and decay. Both contribute to the development of tooth cavities, or dental caries.

Tooth erosion: Our teeth have an outer layer of enamel, which can be eroded by acid. The acid can come from acidic food and drinks that come into contact with teeth. A commonly used measure of acidity is pH, where the lower the pH, the more acidic something is. Tooth enamel is generally considered to be at risk of erosion when the pH of the food or drink is less than 5.5. The lower the pH, the greater the risk of erosion.

Tooth decay: Bacteria in your mouth stick to your teeth, forming plaque. This bacteria feasts on the sugars stuck to your teeth from the food you eat, regardless of the food’s pH. These bacteria produce acid when they consume the sugars, and because the food and bacteria is in contact with your teeth, this acid erodes the tooth enamel.

Starchy foods are partially broken into sugars in your mouth, because one of the enzymes that digests carbohydrates in our gut is also present in saliva, starting the process of converting starch into sugar while it’s still in your mouth (and stuck to your teeth).

So while we hear public health messages about sugar and tooth decay, it’s actually acid that erodes the enamel. However for most people the consumption of sugary foods (which are often ‘sticky’ and remain on your teeth for hours after you’ve eaten) is the main contributor, albeit via an indirect effect.

Our bodies try to combat tooth erosion by neutralising the acid produced by bacteria. Saliva contains bicarbonate, which buffers the acids to neutralise them. In addition, the fluoride in toothpaste (and the water supply in some cities) can strengthen tooth enamel and make it more resistant to erosion from acids.

Cycling and the risk of tooth decay – a perfect storm for cavities?

Dentists are particularly concerned about the oral health of athletes for two reasons:

1. Sports nutrition products like sports drinks and gels are generally quite acidic, and they tend to stick to your teeth due to their sugar content. While there are plenty of normal foods that non-athletes consume that have the same effect (soft drinks/soda, confectionary like snakes, gummy bears and the like, dried fruit and much more), it’s the frequency of exposure during exercise that dentists worry about.

Small but frequent sips or gels every few minutes during a ride rather than eating a few distinct meals or snacks hours apart increases the number of times that acid contacts the teeth.

2. The action of saliva to neutralise the acid in your mouth can be compromised during exercise because heavy breathing can dry your mouth out, reducing the amount of saliva able to protect the teeth. In addition, dehydration can reduce the amount of saliva produced during and after exercise.

Do endurance athletes actually have more dental caries other people?

So all of this is fine in theory, but do athletes actually have higher rates of tooth enamel wear and cavities than non-athletes? While the rate of teeth problems in athletes has been studied extensively (and found to range from 17-75% depending on the study), there are actually very few comparisons to non-athletes. As recently as October 2013, when a large, systematic review was conducted, there was only one study that actually compared the rates of cavities between athletes and a non-athletic control group. And that study looked at wrestlers who don’t actually consume sports drinks during competition, so it’s probably not a great comparison.

Last year, however, a study was published in the Scandinavian Journal of Medicine and Science in Sports, comparing the oral health of 35 German triathletes training at least five hours per week, to 35 non-athletes. They found the number of teeth with cavities was actually the same between athletes and non-athletes, however there was greater tooth erosion in the triathletes, suggesting their risk for future cavities was greater.

Regardless, it’s prudent for cyclists to reduce their risk of cavities by understanding and addressing the factors that increase that risk.

The acidity of on-the-bike nutrition – are they all the same?

While not all research studies agree, the majority suggest pH is an independent contributor to how erosive sports nutrition products are for your teeth. Again, a lower pH means a more acidic substance, and hence a greater erosive potential. With that in mind we decided to test the pH value of common sports foods and drinks. We wanted to know if all products within a category (say drinks or gels) are pretty much the same, if one category is worse than others, or if the pH varied greatly according to the brand.

To achieve this we enlisted the help of Food Technologist Beth Baranda. Beth works in product formulation for Kagome, a company that farms and processes tomatoes and tomato products. Kagome supplies many of the tomatoes that end up in commercial pasta sauces, pizza sauces and tomato pastes in Australia. Beth has a wealth of experience in food product formulation, but has never worked with sports nutrition products before (in fact, she’d never seen a gel before we met).

Just some of the products we tested.

Beth’s work commonly involves testing the pH of tomato products, mainly from a quality and food safety perspective. But with her pH meter and expertise, we were able to test a range of products commonly used by cyclists.

What we tested

We tested 12 commercial sports drinks that were either bottled or made from powder as per packet instructions, as well as Coca-Cola as a reference. We also tested the DIY sports drink included in my previous CT article on DIY sports foods, as well as both plain and flavoured coconut water — all the rage as an “alternative” sports drink a few years ago.

We also tested eight energy gels or chews (i.e. Clif Bloks), the DIY gel from the aforementioned article, and honey which is sometimes used as an alternative.

We also tested an alternative DIY recipe for both the drink and gel, using peppermint tea instead of lemon juice to provide the flavour.

Finally, we tested two solid food options. These take a bit more time and preparation to blend them down with water, and will overestimate the pH slightly. We tested an apple and cinnamon rice cake as per the recipe in The Feedzone Portables, as well as a choc chip Clif Bar.

All products tested were either bought from retail outlets or were leftovers we had lying around at home. No products were solicited from companies for this testing.

Our testing was done in a controlled lab environment, with the pH meter properly calibrated and thoroughly cleaned between each test. Because pH testing gives slightly different results at different temperatures, all our samples were all tested at 20ºC +/- 1.5ºC. All samples were tested twice and the average used. All but two samples varied by less than 2% between tests, with the remaining two varying by less than 2.5%.

The pH-testing setup.

Test results

The graph below shows the test results. If you’ve done high school chemistry you’ll probably remember that pH is a logarithmic scale. That is, a pH of 3 is 10 times more acidic than a pH of 4, and a pH of 2 is 100 times more acidic than a pH of 4. For that reason I’ve graphed pH against acidity (hydrogen ion concentration in mol/L), so you can see the effect of changing pH across the range of products. Remember that erosion of tooth enamel happens at a pH of less than 5.5.

Generally speaking, most commercial sports drinks fell in a pH range of 2.9 to 3.5, which is in line with previous research. Gels were slightly less acidic, mostly falling in a range of 3.5 to 4.1. But there were some notable exceptions:

– The sports drinks marketed as being more “natural”, and made from dehydrated fruit rather than using flavour additives, had a higher pH. Skratch Labs Orange had a pH of 4.62 and Pure Sports Nutrition Superfruits registed as 4.59.

– The Etixx Isotonic drinks had a much higher pH than all the other brands (5.04 for Watermelon, 5.78 for Orange). Beth explains that the orange flavour of Etixx includes sodium citrate instead of sodium chloride, and the citrate helps buffer the acidity from the citric acid. The watermelon flavour actually uses sodium chloride, but watermelon flavouring is actually not particularly acidic in the first place, and less citric acid is usually added to watermelon-flavoured products for taste reasons.

– Torq brand gels (two different flavours tested) had a much lower pH (2.5-2.8).

– The DIY sports drink and gel using lemon juice were the most acidic of all (pH of 2.77 for the drink and 2.32 for the gel). Beth suggested that I simply use sodium citrate instead of salt (sodium chloride) when making it to increase the pH substantially. But given this ingredient is more expensive and less easily available, it arguably defeats the purpose of the DIY options.

– As noted above, we tried making the DIY drink and gel with peppermint tea instead of lemon juice. This dramatically increased the pH to the highest levels of any product tested (drink was a pH of 6.26, gel was 6.07). This result is similar to previously published research that tested a similar recipe.

There were some other notable observations from the testing:

– The bottled Gatorade had a higher pH than when the same flavour was made from powder, but the differences were small and not particularly important. For example, lemon-lime had a pH of 3.13 bottled, and 2.94 when made from powder.

– Honey had a pH right in the middle of the range of gels (3.91).

– The apple and cinnamon rice cake had a pH of 3.90, which reflects the normal pH of apples — the main ingredient in the cake. We would expect the savoury rice cakes from the book to have a much higher pH.

– The Clif Bar had a pH of 6.25, which may be a slight overestimate, as explained above. But generally speaking this was much less acidic than other options.

– The flavoured coconut water had a higher pH than most commercial sports drinks, but was still more acidic than many other products at a pH of 4.24. Even plain, packaged coconut water had a pH of 4.98.

These results prompt the question – why are all these products so acidic? Beth explains that the pH of products is important not only from a shelf life/food safety perspective, but also to make the product palatable. The citric acid used in most commercial soft drinks, cordials, confectionary and sports drinks provides that characteristic “tang” in your mouth. Without it they would taste quite bizarre.

How to reduce the risk to your teeth

If you’re a rider concerned about your teeth, there are a few things you can do to reduce the risk of avoidable erosion of your teeth. Firstly, choosing higher pH products is likely to reduce the erosion to some degree. This will probably mean having more solid foods like bars and bananas (which have a pH around 4.5 to 5) and fewer gels or sports drinks as your carbohydrate source. This is assuming, of course, that you can tolerate the more solid foods on the bike.

Some of the commercial products we tested also had a higher pH and may be a better choice, although this list is by no means extensive.

Finally, the DIY option using peppermint tea or some other herbal infusion may be a good, higher pH alternative to sports drinks if you like the flavour. Beth also mentioned that some fresh fruit or vegetable juices and purees often have a higher pH, but they also tend to have a higher osmolality (the number of particles within a volume of liquid), which has the potential increase the risk of gut issues during exercise.

We also need to address some of the common myths around sports nutrition products and enamel erosion. Firstly, following up a sports drink or gel with a rinse of water has minimal impact. By the time you’ve rinsed, the acid from the product has already done its thing.

Secondly, brushing your teeth immediately after exercise is also not recommended. In the dental health fact sheet by Sports Dietitians Australia and the Australian Dental Association, it is pointed out that the softening of tooth enamel from acidic foods and drinks last for about 60 minutes after contact. Brushing during this time will actually increase the enamel erosion, so it’s best to wait at least an hour after contact with acidic foods before brushing.

The final thing to consider is whether you even need acidic and sugary products on the bike. There are plenty of times when loading up on carbs is completely unnecessary, so saving these products for when you really need them is a wise move. Carbohydrate is of most value on the bike for training when there’s high-intensity efforts involved (and the quality of those efforts is important), during racing of one hour or more, or during very long recreational events where you need the fuel to get through (gran fondos and similar rides that challenge your current level of fitness).

There’s no point gulping down sports drink on an easy social ride with your mates and, as you can see from the test results above, it’s only going to increase your risk of cavities.

Acknowledgement

We are very grateful to Beth and the team at Kagome for allowing us to use their pH meter and test the various products. These meters are very expensive and Kagome allowed us to do this free of charge, expecting nothing in return.

About the author

Alan McCubbin is an Accredited Sports Dietitian, Accredited Practicing Dietitian and past president of Sports Dietitians Australia. He is also the founder of Next Level Nutrition, an online sports nutrition consultancy through which he works with a range of athletes from recreational to Olympians.

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