Why do you get ‘morning breath’ and can you stop it?

“…how can you get such bad breath even if you brush your teeth really well, floss, and use high-strength mouthwash before you sleep?”

002 of 365 by Yogesh Mhatre, on FlickrThe malodorous criminals here are the several million bacteria that grow in your mouth during the night. First off, there are hundreds of different types of bacteria in our mouths, all of which produce a multitude of by-products, including gases. These gases are mostly sulphur based and, as anyone can say after cracking a bad egg, sulphur is not a pleasant smell. These vapours are produced by the bacteria breaking down proteins and amino acids found in the perfectly suitable Petri dishes that is our mouth (in other words the microbes eat, grow and excrete by-products such as gas). The “morning breath” gases have delightful names such as methanethiol (faecal odour) and isovaleric acid (sweaty odour), cadaverine and putrescine, all of which combine into a fragrant blend we associate with bad breath.

But if we get rid of all these bacteria at night, why does it reek so badly in the morning? This is where the growth cycles of the microbes are important – mouth bacteria are constantly growing and dying. Brushing, flossing and gargling mouth wash kills many bacteria and creates an environment unfriendly towards them, but the effects do not last very long. Dental hygiene does not kill all of them and the few that survive multiply and grow through the night (if you think it’s unlikely that bacteria can grow that fast, consider that Escherichia coli can double its numbers in 17 minutes). Furthermore, most people don’t brush their tongue, the roof of their mouth, or the back of their throat, which is where bacteria thrive. The pong of sulphur is also made worse by a dry mouth. Saliva curbs bacterial growth but when you sleep you don’t move the saliva around your mouth as much as you do when you’re awake which allows for increased bacterial growth (dehydration is also worsened by alcohol consumption). The bad breath smell is also aided by stomach and intestinal gases bubbling up to the mouth and mixing with the already present sulphur gases. Isn’t the body a wonderful thing?

The best advice for banishing bad breath is to visit your dentist regularly to eliminate tartar build up, brush and scrape your tongue (with an often cleaned tongue scraper) and drink plenty of water. And brush your teeth before kissing your loved one.

Answer by Janske Nel

Question from Zoe B via website

Image source: Yogesh Mhatre on Flickr

Article by Janske Nel

February 11, 2014

Janske Nel is currently busy with her second year of a Master’s in Nanotechnology, centred specifically on nano-oncology, at the University of the Western Cape, South Africa. She shows no fear in the face of spiders, snakes or long hours in the laboratory, but shudders at the thought of books left face down.


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