One of the more puzzling consequences of old age is a decreasing ability to appreciate the taste of a fine meal. Actually, the problem is not only a matter of taste. It also has to do with smell.

When we eat something, we rely on a combined sense of taste and smell to experience flavor. The next time you're eating fruit-flavored candy, try this. Grab a handful of candy, close your eyes, and pick one. While pinching your nose shut, pop the candy into your mouth.

Chances are you'll taste the tart sweetness of the candy, but you won't recognize a particular flavor. Now let go of your nose. Presto! The savory flavor of banana-grape fills your mouth.

Taste is a limited sense; the taste nerves in the mouth and tongue only detect combinations of sweet, sour, salty and bitter. Flavors, on the other hand, vary widely, numbering in the tens of thousands. When we experience these many flavors, we use our nose as much as our mouth.

For example, when you chew a piece of candy, you inhale the candy's chemicals through your mouth and exhale them through your nose. As they pass through the nose, the chemicals trigger receptors that send smell and flavor signals to the brain.

The body tends to break down in old age, and taste and flavor receptors are no exception. Although taste buds in the mouth tend to lose some sensitivity, it is the decrease in the number of active flavor receptors in the nose that make it more difficult for elderly diners to truly savor an exquisite meal.

【譯文】：

人到老年，一個令人費解的苦惱就是對美味佳肴品鑒能力的降低。事實上，問題不單單出現在味道上，同時還出現在嗅覺上。

當我們吃某樣東西的時候，我們依賴融合了的味覺和嗅覺去體驗味道。下一次你吃水果糖時，不妨試一試。抓一把糖果，閉上眼睛，隨意挑選一顆。捏著鼻子把糖果放進你的嘴里。

你可能嘗到糖果的酸甜的味道，但是你分辨不出獨有的味道。現在讓你的鼻子自由呼吸，轉眼間，香蕉葡萄那可口的味道布滿你的口中。

味覺是被限定的感覺，你口中和舌頭上的味覺神經僅僅能夠分辨出酸，甜，咸，苦。但味道多種多樣，有上萬種之多。當我們品嘗這些味道的時候，鼻子和嘴一樣功不可沒。

舉個例子來說，當你嚼一塊兒糖，你用嘴來吸收它們的化學成分，再用鼻子釋放出來。當她們通過你鼻子的時候，這些化學成分激發(fā)受體，把嗅覺和味道的信號發(fā)送給大腦。

到了老年，身體衰退，當然，味覺和味道受體也不可幸免�？谥械奈独俾�慢失去一些敏感性，鼻子中那些活躍的味道受體的減退讓老年人更加困難地去享受精致佳肴。