Dentists are more and more concerned about dental erosion, which is the loss of enamel (the hard tissue at the surface of your teeth) due to acids. As soon as the pH in your mouth reaches 5.5 the enamel starts to dissolve, which makes your teeth discolour, become more sensitive and finally erode away. The acidity can come from food or drinks, or from reflux of gastric contents. Bacteria can also produce acids, but this leads to caries.
To protect your teeth, you need not only good hygiene, but also abundant saliva with a high pH and good buffering capacity to wash food rests away and neutralise the acidity. Unfortunately exercise reduces the salivary flow rate, and scientists think this could be one of the reasons –or even the main reason- why athletes suffer more from tooth decay and erosion than other people.
Mai Tanabe and her colleagues have just published a study about the effects of drinks and food during exercise on the salivary flow rate, pH and buffering capacity. Ten volunteers exercised on bicycle ergometers for 20 minutes at 80% of their maximal heart rate, rested for five minutes and cycled again for 20 minutes. Each of them performed the test five times: 1) without any drinks or food, 2) using mineral water, 3) using mineral water with jellies, 4) using sport drinks and 5) using sport drinks with jellies. The researchers collected samples of their saliva before, during and after each exercise bout.
As expected, the salivary flow rate decreased significantly when the volunteers did not drink or eat anything during the workout. Drinking or eating restored it. The pH decreased when they used sport drinks, but remained unchanged when they had mineral water. The buffering capacity always declined, except when mineral water was used.
You can see the results here: http://www.jissn.com/content/10/1/49/figure/F1
The researchers therefore concluded that, from a purely dentist point of view, using mineral water with or without food was best. They admitted however, that you might have more important reasons to prefer sport drinks. If so, they advised to rinse your mouth as quickly as possible after your workout.
If the volunteers had to drink during a 2 x 20 minutes workout to keep their salivary flow and buffering capacity, I get the impression that we, distance runners, are a hopeless case! Drinking that often during a long run might put you at risk of overhydration and therefore hyponatremia, which can be fatal. I guess my best option is to keep visiting my dentist on a regular basis…
Disclaimer: this article is for general information only, and does not replace medical advice. It cannot be used to diagnose or guide treatment. If you have any concerns or questions, you should talk to a qualified health provider.
Aida Mulic, Anne Bjorg Tveit, Dag Songe et al. Dental erosive wear and salivary flow rate in physically active young adults. BMC Oral Health 2012; 12:8 doi: 10.1186/1472-6831-12-8.
Yan-Fang Ren. Dental erosion: etiology, diagnosis and prevention. Accessed on 25/02/2014
Mai Tanabe, Toshiyuki Takahashi, Kazuhiro Shimoyama et al. Effects of rehydration and food consumption on salivary flow, pH, and buffering capacity in young adult volunteers during ergometer exercise. J Int Soc Sports Nutr. 2013; 10:49 doi: 10.1186/1550-2783-10-49.