Bad Breath

Do you fear your breath is strong enough to scare small children? You might be mistaken. People are notoriously inept at assessing the odor of their own exhalations. A breath-mint addict who constantly worries about his breath may never have had a problem. At the same time, a person with truly noxious breath may be baffled when friends start offering mints or backing away during a conversation.

If you’re worried about your breath, get a second opinion: Ask a close friend or loved one if your breath is up to par, and urge them to be honest. If the news isn’t good, don’t panic. Bad breath doesn’t have to be permanent. By taking a few simple steps, you can freshen your breath and win back your confidence.

Bacteria: The chief cause of bad breath

Bad breath, also known as halitosis, may go far beyond a tinge of garlic or onions. Like other types of body odor (the aroma of sweaty feet, for instance), many forms of halitosis are the handiwork of bacteria. When the germs that live in the mouth break down food particles and other debris, they often foul the air with highly pungent chemicals.

For example, some types of oral bacteria produce hydrogen sulfide, the compound that lends the distinctive aroma to rotten eggs. Others produce methyl mercaptan, the chemical that makes feces smell like feces. Still others release putrescine, the aroma of rotten meat. As for the bacteria that produce cadaverine … well, the name says it all.

Hydrogen sulfide, methyl mercaptan, and other compounds most often associated with bad breath are known in the dental trade as volatile sulfur compounds, or VSCs. (“Volatile” means “vaporous” and “effervescent,” in this case.) These odor-causing compounds are produced by microbes that often live on bits of food that cling to the back of the tongue or get stuck between teeth. They can also thrive in the pockets between the gum and tooth, particularly if you have serious or even mild gum disease.

Bacteria also tend to do extremely well in mouths that don’t produce enough saliva to rinse away food particles. And if you have postnasal drip from chronic allergies or sinusitis, mucus can collect on the back of your tongue and provide rations for an army of bacteria.

Garlic, cigarettes, and other culprits

Of course, strong-smelling foods can ruin breath without the help of bacteria. According to a report from the Academy of General Dentistry, onions and garlic can stay on the breath for 72 hours after a meal. Coffee and cigarettes are also notorious for their lingering odors.

With the recent popularity of high-protein diets, some people have experienced another diet-related cause of bad breath. High-protein diets often limit the amount of carbohydrates you may eat. When your body doesn’t receive enough carbohydrates to use as an immediate source of energy, it begins to break down fat and other tissues. This releases by-products called ketones into your system. Elevated ketones can cause “keto breath,” which some have described as smelling like a combination of nail polish and overripe pineapples! (Ketones are also sometimes on the breath of people who are on very low calorie diets, and patients with poorly controlled diabetes.)

Other causes of bad breath include periodontal disease, respiratory infections, sinusitis, bronchitis, and diabetes. Contrary to common belief (and the advertising claims of some products), bad breath rarely comes from the stomach.

I’ve been reading about “halitosis clinics.” How would doctors there analyze my breath?

Some clinics use gas chromatography, which analyzes the gases you’re breathing out, while others use a portable monitor that detects VSC levels. High-tech methods aside, at least one researcher has recommended the “sniff test” — having a professional smell the air expelled from a patient’s mouth — as the most reliable method.

What’s the link between gum disease and bad breath?

Studies conducted over the last 50 years have confirmed the link between gum disease and offensive odor, according to a research review published in a leading dental journal. “A more disagreeable odor” emanated from the mouths of people with gum disease because their saliva putrefied more rapidly that that of healthy individuals, according to the review.

Several clinical studies also showed elevated levels of VSCs in the pockets of inflamed gums, and the more diseased the gums, the higher the levels, the review reported. People with chronic gum disease also have more “tongue coating” — and four times the production of odor-producing VSCs — than individuals without gum disease. Finally, dental plaque, composed of bacteria as well as proteins, contributes to an unpleasant smell. All this adds up to what dentists refer to as “oral malodor,” otherwise known as bad breath.

How do I get rid of bad breath?

A clean mouth is the best defense against bad breath. See a dentist regularly, floss between your teeth every day, and brush with a fluoride toothpaste two to three times each day. (One study also found that toothpastes with a high concentration of baking soda reduced bad breath.)

And don’t neglect your tongue, especially the back section. By brushing it gently with a toothbrush or using a plastic tongue scraper (also gently!), you can deprive bacteria of a prime breeding ground. Go slowly and you’ll learn to avoid the gag reflex. According to one study published in the Journal of Clinical Periodontology, after dental and tongue cleaning, concentrations of key odor-causing bacteria dropped from 75 to 25 percent.

Finally, have your teeth cleaned professionally by a dental hygienist every six months.

For extra protection, you can kill odor-causing germs by gargling a mouthwash right before bedtime. Only a few kinds appear to work well, however — avoid brands that contain alcohol, since such a mouthwash has a drying effect and can accelerate the development of bad breath.

Some dental researchers have found mouthwashes containing zinc chloride, hydrogen peroxide, chlorine dioxide, or other oxidizing chemicals to be effective in reducing or eliminating bad breath. According to Dr. Harold Katz, founder of California Breath Clinics, the only effective mouthwashes are those that “oxidize” volatile sulfur compounds and turn them into non-odorous organic salts.

What else can I do to eliminate bad breath?

In addition to good oral hygiene, regular meals (especially a good breakfast) can help keep your mouth moist and fresh. Avoiding cigarettes should be a top priority for anyone who cares about breath odor. And, of course, it’s wise to go easy on the garlic and onions before a big date. If you have coffee breath, you might want to cut back on coffee, too.

Don’t count on mints and gums to save your breath. Although they may make your mouth feel temporarily fresh and clean, they do little to fix the root cause of bad breath. And even though sugarless gum is recommended to help stimulate the production of saliva in people with dry mouths, at least one study has linked it to increased levels of methyl mercaptan, one of the principal components of bad breath.

Several recent studies have also found that taking certain probiotics, or beneficial bacteria, may help ward off bad breath.

When should I see my dentist about bad breath?

If daily flossing along with tooth and tongue brushing doesn’t seem to help, schedule an appointment with your dentist. You may have gum disease, stubborn plaque, or another condition that requires treatment. If you’re taking a prescription medicine and have persistent dry mouth, you may need to talk with your doctor about whether it’s possible to switch to another drug. Hundreds of medications have the potential to dry out the mouth, and a different type or smaller dose could solve the problem.

In the best-case scenario, you may be one of the lucky ones whose breath gets rave reviews. If so, that doesn’t mean you should ignore oral hygiene. Keep your mouth clean and moist, and you have a good chance of avoiding putrescine, cadaverine, and those other unwanted bacterial guests. Your breath will stay fresh, sighs of relief included.


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Karen Ensle, Kathleen Shimomura Fad Diets: Healthy or Hazardous? Rutgers Cooperative Extension Fact Sheet.

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