Periodontal disease

Gum disease causes a collection of bacteria to grow and multiply in pockets just under the gumline, where it's protected from the rest of the mouth. These bacteria can damage the gums and supporting structures, causing bleeding and release of smelly Hydrogen Sulphide and Methyl Mercaptans compounds.

Dry mouth

Dry mouth can increase mouth acid and deprive the mouth of oxygen. This in turn will degrade the quality of saliva you produce and then finally cause an increase of the anaerobic bacteria that cause the bad breath.

Genetic predisposition

Clearly there are some people who inherit a predisposition to problem breath which makes it harder to combat.

Low-carb diets

Atkins diets and similar no-carb fad diets cause the body to break down fats and release ketones. This creates a particular type of bad breath called "Hunger Breath".

Medications

Seven out of the top ten prescribed medicines have dry mouth as a side effect of usage. Typically they are the antidepressants, high blood pressure medicines, antihistamines, decongestants, indigestion, hormone replacement medicines and birth control pills.

Smelly foods

Garlic and onions will create bad breath instantly. This is because they already contain the sulphur compounds (known as mercaptans) produced by bacteria.

Smoking

When you smoke, you are effectively starving the mouth of oxygen, thus promoting the overgrowth of anaerobic bacteria that create the smelly sulphur products.

Alcohol

Alcohol is a very good drying agent. It drastically increases the numbers of anaerobic bacteria and is a major cause of dry mouth.

For more details on bad breath, go to Dr Speiser's comprehensive website at www.breezecare.com.au< /a>

Catherine Saxelby is a nutritionist and author of Nutrition for Life. Get more healthy eating tips at www.foodwatch.com.au