People tend to blame what they eat for having bad breath. However, other elements, including poor oral hygiene or sometimes even an underlying health condition, could be the reason for this common condition, medically known as halitosis.

Bacteria in your mouth are usually to blame for the unwanted odor. And what you eat naturally plays a role too. "Bad breath is often caused by certain foods or poor oral hygiene," points out dentist Dr. Christoph Sliwowski. "When bacteria in your mouth break down food particles, unpleasant-smelling sulfur compounds are produced."

If you don’t brush your teeth and tongue regularly and thoroughly, more food particles remain in your mouth and plaque (a sticky film of bacteria) forms on your teeth, "increasing the foul odor of sulfurous gases," he explains.

To combat bad breath effectively, you need to practice good oral hygiene that goes beyond daily toothbrushing. "This includes using dental floss, for example," says Dr. Christoph Benz, president of the German Dental Association (BZÄK).

"Cleaning your tongue is important too," he adds, because between 60% and 80% of the bacteria that cause bad breath are found on the tongue. "Daily cleaning with a tongue scraper will sharpen your sense of taste, make your mouth feel fresher and reduce bacteria."

Saliva production plays a big role as well. "If too little saliva is present – because you don’t drink enough fluids or have a dry mouth due to anxiety or stress – your breath will have a pungent odor," remarks Benz.

Using chewing gum can help. "It’s a great way to prevent bad breath," he says. "It cleans your teeth and at the same time stimulates saliva production. It’s important that the gum is sugarless though."

Sliwowski also recommends mouthwashes – in moderation. "Mouthwashes provide extra cleaning and freshen your breath," he says, but cautions that they shouldn’t be used constantly, as they can disrupt the normal balance of oral flora.

If you brush your teeth and tongue daily yet still have the smell – or are told by others – that you’ve got chronically bad breath, you should see a dentist, who can determine the cause, Sliwowski says.

The root of the problem could be periodontitis, which is a severe inflammation of the gums, or ill-fitting dentures if you wear them. In rare cases, a disorder of the stomach or oesophagus (food pipe) is responsible.

Short-term bad breath is often the result of the foods we’ve eaten most recently. Garlic is notorious in this regard. A natural constituent of fresh garlic is the amino acid derivative alliin, an odorless sulphoxide. But when garlic is chopped, crushed, cooked or chewed, an enzyme converts alliin into the organosulphur compound allicin, which does smell. Allicin then breaks up into other pungent organosulphur compounds, including ajoene.

These stinky compounds stick to the mucous membrane of the mouth, enter the bloodstream via the digestive tract and exit the body in part through the skin. "Smoking or drinking alcohol intensifies the smell," Sliwowski says. "If you want to tone down the unpleasant effect, you shouldn’t chop or crush the cloves," he advises. Instead, you could cook them whole and then remove them, leaving the food with a garlicky aroma.

"As an alternative," says Sliwowski, "some foods take the edge off bad breath. Chewing parsley, mint or sage, for instance, releases essential oils that counteract bad breath caused by garlic."

Eating a raw apple or drinking lemon juice or green tea can neutralize the offending sulfur compounds as well. And when you eat something spiced with garlic, it’s important to drink plenty of fluids to wash down food particles and stimulate saliva production.

All of this advice is well and good, but you’ve got to realize you have bad breath before you can combat it. This is often a problem.

"It’s like all chronic smells: Once you get used to it, you don’t notice it anymore," says Benz. "That’s why a lot of people aren’t aware of the foul smell in their mouth."

If you think you might be one of them, ask people close to you for a frank assessment. "Studies show that honest questions get honest answers, even when they involve bad breath, which is still a taboo subject," he says.

There’s a way to test your breath yourself: "Put some of your saliva on your inner wrist, let it dry briefly and then sniff it," recommends Benz, noting it must have a very strong foul odor to indicate bad breath.

Some people have an exaggerated self-awareness in this regard, thinking they have bad breath when they don’t, Benz says. You shouldn’t make the mistake of sniffing dental floss after using it, for example, since "it’ll never have a pleasant smell."