Breath only smells when certain aromatic chemicals are found dissolved within it. These include methyl mercaptan, hydrogen sulphide and putrescine. Some of these may be absorbed from the bowel into the bloodstream and then circulated around the body until they are excreted via the lungs in the breath. In the same way, garlic rubbed into the soles of the feet can later be detected in trace amounts in the breath.

Morning breath

Practically everyone has a degree of halitosis first thing in the morning. There is a physiological reason for this. During sleep, the flow of saliva is drastically reduced and the tongue and cheeks move very little. This allows food residues to stagnate in the mouth and dead cells that are normally shed from the surface of the tongue and gums and from the inside of the cheeks to accumulate. As bacteria start to work on them and digest them, an unpleasant smell is generated, the result, if you like, of a process known in biological terms as putrefaction. Although normal, anyone suffering from nasal congestion that mouth-breathes is more likely to suffer from these actions to a greater extent. Luckily, this morning breath generally disappears after breakfast and after brushing the teeth because saliva starts to flow again and any left over residues are washed away and swallowed.

Occasional bad breath

The commonest causes of occasional halitosis include smoking cigarettes or cigars, drinking alcohol or eating certain foods. Culprits that are often blamed include onions, garlic, curries, and cured foods like salamis and cooked foods such as kippers. In addition to making the breath smell like an ashtray, smoking also reduces the flow of saliva in its own right and therefore further exacerbates the problem.

Medical causes of bad breath

Most reasons for halitosis are sited in the mouth. Gum disease is the commonest reason of all, as any reputable dentist will confirm. Plaque is a mixture of bacteria, food residues and dead gum cells that forms between the gum and the tooth. The bacteria here create the unpleasant odor and contribute as part of the plaque to bleeding gums and loosening of the teeth in the future. Often the reason is simply down to bad oral hygiene. If you do not regularly brush your teeth you will experience bad breath. And a coated furry tongue is often a sign of indigestion, smoking or dehydration, all of which can produce the problems of malodorous breath.

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