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.

【译文】：

人到老年，一个令人费解的苦恼就是对美味佳肴品鉴能力的降低。事实上，问题不单单出现在味道上，同时还出现在嗅觉上。

当我们吃某样东西的时候，我们依赖融合了的味觉和嗅觉去体验味道。下一次你吃水果糖时，不妨试一试。抓一把糖果，闭上眼睛，随意挑选一颗。捏着鼻子把糖果放进你的嘴里。

你可能尝到糖果的酸甜的味道，但是你分辨不出独有的味道。现在让你的鼻子自由呼吸，转眼间，香蕉葡萄那可口的味道布满你的口中。

味觉是被限定的感觉，你口中和舌头上的味觉神经仅仅能够分辨出酸，甜，咸，苦。但味道多种多样，有上万种之多。当我们品尝这些味道的时候，鼻子和嘴一样功不可没。

举个例子来说，当你嚼一块儿糖，你用嘴来吸收它们的化学成分，再用鼻子释放出来。当她们通过你鼻子的时候，这些化学成分激发受体，把嗅觉和味道的信号发送给大脑。

到了老年，身体衰退，当然，味觉和味道受体也不可幸免。口中的味蕾慢慢失去一些敏感性，鼻子中那些活跃的味道受体的减退让老年人更加困难地去享受精致佳肴。