美国新闻和世界报道资深记者 Megan Johnson

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你是否有亲朋好友礼貌地提示你呼吸的味道不好？（许多口臭患者可言其中之苦）。勤刷洗和牙线清理牙齿可能赶走口臭，但专家认为多清理牙齿并非总是奏效，下列导致口臭的八个原因可能你不知道：

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药物

唾液可以把导致口臭的细菌冲洗掉，但某些药物，比如抗抑郁药、利尿剂甚至阿斯匹林都可使唾液减少而口干，细菌繁殖而致口臭。

细菌

发臭味的细菌菌株多在舌头上繁衍，当它们吞食食物残渣和唾液分解出的物质时就会洋洋得意地释放出臭气。在夜间唾液腺分泌减缓时，细菌繁殖旺盛，因此早晨往往口臭严重。某些人比别人的口中含更多的发臭的细菌菌群，因此某些人就更易发生口臭。本月在《微生物医学杂志》的研究提示胃幽门螺旋杆菌（H.pylori），即那些可以导致胃溃疡的细菌，如果在口腔中落户的话，也可以导致口臭和牙龈疾病。

呼吸道感染

牙齿和牙龈的感染是已知导致口臭的根源。但气管炎、鼻窦炎甚至感冒也可导致口臭。上呼吸道感染使组织脱离，坏死细胞和分泌物增多喂养了细菌而致口臭。

不吃早餐

吃好早餐对身心的益处已经被充分证实，除此之外吃早餐还可以通过刺激唾液的产生和摩擦掉舌头上的细菌而减除口臭（但吃沙丁鱼元葱三明治除外）

饮食

吃富含蛋白质食物和奶制品都会产生大量的氨基酸，成为细菌的养料。饮食中的碳水化合物减少时就会燃烧脂肪，从而产生毒性气味的酮体。去年研究者还发现口臭与肥胖有关，尽管证据尚显不足。

口腔呼吸

能使口腔组织干燥的任何情况都会阻止唾液对细菌的冲刷清除而导致口臭。迫使病人用口腔呼吸而不用鼻腔呼吸的疾病有睡眠呼吸暂停、打鼾以及哮喘病。

所罹患的疾病

呼吸气味难闻预示着特殊的疾病，比如，肾功能衰竭可产生臭鱼味的口臭，控制不利的糖尿病口里可产生水果的腐烂气味。

酗酒

大量饮酒可使口干燥细菌滋生而导致口臭。

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8 Surprising Causes of Bad Breath

By Megan Johnson

Posted December 2, 2008

Has a friend or significant other gently hinted that your breath is, um, pungent? (Many halitosis sufferers can't tell.) Brushing and flossing more diligently may do the trick, But a few more minutes at the sink won't always help, say experts. Here are eight causes of bad breath that may surprise you: 

Medications. Saliva rinses away bacteria that foul the breath, and many drugs, among them antidepressants, diuretics, and even aspirin, can dry the mouth.

Bacteria. The stink-creating kind mostly hang out on the tongue, happily churning out gases as they munch on food particles and substances broken down from saliva, and multiply at night, when the salivary glands slow down (hence morning breath). Some people harbor more species of malodorous bacteria than others do, which may be why certain individuals are especially halitosis-prone. This month, a study in the Journal of Medical Microbiology suggests that H. pylori, the same bug that is often responsible for stomach ulcers, can cause bad breath and gum disease if it finds a home in the mouth.

Respiratory tract infections. Tooth and gum infections are recognized sources of bad breath. But so are bronchitis, sinusitis, and even a cold. RTIs break down tissue, starting a flow of cells and mucus that feed bacteria that create foul odors. 

Skipping breakfast. Besides the well-established advantages to body and mind of having a good breakfast, it helps quell morning breath by stimulating saliva production and scrubbing bacteria from the tongue. (But lay off the sardine-onion sandwich.)

Diet. Foods high in protein or dairy products generate large amounts of amino acids, which are fodder for bacteria. A diet low in carbs burns stored fat, creating toxic-smelling ketones. And last year, researchers linked bad breath with obesity, although the basis is unclear.

Mouth breathing. Any condition that dries the tissues of the mouth, preventing saliva from washing away bacteria, encourages bad breath. Candidates include sleep apnea, snoring, and asthma.

Ongoing illnesses. A potent breath can signal particular diseases. Kidney failure produces a fishy smell and uncontrolled diabetes generates fruity fumes, for instance.

Alcohol. Heavy alcohol consumption also can dry out the mouth.