雅思阅读材料之口臭是怎么回事？

It's not your fault if you have bad breath.

 

In fact, most people with halitosis are so concerned about it that they tend to have far better oral hygiene practices than the average person.

 

According to the most current research, over 90 percent of all cases of chronic bad breath originate in the mouth, NOT in the stomach, sinuses, or lungs. Virtually all cases of bad breath are caused by Volatile Sulfur Compounds (VSCs). One compound is hydrogen sulfide (the rotten egg smell) and another is methyl mercaptan (the essence of skunk oil).

 

The source of these compounds is bacteria in the mouth breaking down the cell wall of dead cells. These anaerobic bacteria collect and multiply mainly on the tongue. They thrive in a dry, dark environment such as under the gums, the spaces between the teeth, and the crevices of the tongue.

 

A person's diet can cause bad breath, because certain foods can trigger a substantial increase of anaerobic bacteria that produce VSCs. Coffee, an integral part of our society, contains acids that decrease oxygenation of the mouth, which, in turn, increases bacteria production. Dairy products, the focus of a recent media blitz promoting healthy eating habits, are high in proteins that the bacteria break down to create the VSCs. Sugar containing mints and chewing gum also produce VSCs, when the anaerobic bacteria break them down. Spicy foods and onions contain sulfur byproducts that are absorbed into the blood stream, and are expelled by the lungs. Additionally, alcohol-containing mouth rinses dry the mouth, causing a condition by the name of xerostomia, or "Dry Mouth Syndrome."

 

Dieting can cause bad breath in the form of a hunger odor, a.k.a. "morning breath," which goes along with the sensation of hunger. Some evidence leads to the conclusion that this odor is a product of the decomposition and rotting of pancreatic juices, which passes into the stomach while the body fasts. The odor worsens if one skips breakfast.

 

Gum disease, most certainly, can cause bad breath, because food trapped in gum pockets can rot and ferment, which releases sulfur products, and increases tartar buildup on the teeth, which also traps bacteria that release sulfur products. Most know that smoking causes bad breath, and that heart problems eventually result from the habit, but few realize that smoking causes gum disease, and that gum disease can cause heart problems.

 

Certain medications, for example blood pressure medication, antidepressant medication, antihistamine medication, and cold medication, just to mention a few, cause "Dry Mouth Syndrome." This syndrome decreases saliva production, leaving the mouth without a lubricant to cleanse itself and to remove food particles.

 

Distinctive odors are often associated with certain medical conditions, and can play a critical role in detecting and diagnosing potential life-threatening illnesses. Common medical conditions associated with halitosis include respiratory infections, such as infections of the nose, windpipe, or lungs, chronic bronchitis, postnasal drip, and sinusitis. Other conditions include, but are not limited to, diabetes, gastrointestinal disorders, liver or kidney disorders, and metabolic disorders.

 

halitosis: 口臭

 

sinuses: 鼻窦

 

anaerobic: 厌氧的

 

rinse: 清洗

 

pancreatic: 胰腺的

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