Can milk make you happy?
　　 Can fish make you smart?
　　 Imagine yourself lying in bed, your mind in turmoil. You toss and turn, but sleep won't come. Maybe a bedtime snack would help. What should you choose? If you think first of toaster waffles or popcorn, some experts would say you're on the right track. Foods high in complex carbohydrates-such as cereals, potatoes, pasta, crackers, or rice cakes-make many people relaxed and drowsy.
　　 Missed that one? Try again. Suppose the weather's rotten, you forgot your homework, and your best friend's mad at you. What's good medicine when you're feeling low? A sugary cola or candy may give you a quick lift, but you'll crash just as quickly. Better choices may be Brazil nuts (for selenium), skim milk (for calcium), or a spinach salad (for folic acid). In research studies, all three of those nutrients have been shown to lift spirits and battle the blues.
　　 Try one more. You have a math test coming up in the afternoon. You want to be sharp, but you usually feel sleepy after lunch. Is your best choice an energy fix of fries and a shake or a broiled chicken breast and low-fat yogurt? If you pick the high-fat fries and shake, you may feel sluggish and blow that test. The protein-rich chicken and yogurt are better choices. Protein foods energize, some experts say.
　　 How does food affect mood and mind? The answer may lie in the chemistry of the brain and nervous system. Molecules called neurotransmitters are chemical messengers. They carry a nerve impulse across the gap between nerve cells. The release of neurotransmitter molecules from one neuron and their attachment to receptor sites on another keep a nerve impulse moving.
　　 Nerve impulses carry messages from the environment to the brain, for example, the pain you feel when you stub your toe. They also carry messages in the other direction, from the brain to the muscles. That's why you back away from the obstacle that initiated the pain signal and exclaim, "Ouch!"
　　 "Many neurotransmitters are built from the foods we eat," says neuroscientist Eric Chudler of the University of Washington. Too little or too much of a particular nutrient in the diet can affect their production, Chudler says. For example, tryptophan from foods such as yogurt, milk, bananas, and eggs is required for the production of the neurotransmitter serotonin. Phenylalanine from beets, almonds, eggs, meat, and grains goes into making the neurotransmitter dopamine.
　　 Dozens of neurotransmitters are known; hundreds may exist. Their effects depend on their amounts and where they work in the brain. The neurotransmitter serotonin, for example, is thought to produce feelings of calmness, relaxation, and contentment. Drugs that prevent its reuptake (into the neuron that released it) are prescribed to treat depression. In at least some healthy, nondepressed people, carbohydrate foods seem to enhance serotonin production and produce similar effects. "It is the balance between different neurotransmitters that helps regulate mood," Chudler says.
　　 Proper nutrition may also enhance brainpower. Choline is a substance similar to the B vitamins. It's found in egg yolks, whole wheat, peanuts, milk, green peas, liver, beans, seafood, and soybeans. The brain uses it to make the neurotransmitter acetylcholine. To test the effects of choline on memory and learning, researchers at the Massachusetts Institute of Technology gave memory tests to college students before increasing the amount of choline in their subjects diets. Later, they retested. On the average, memories were better, and the students learned a list of unrelated words more easily.
　　 考研詞匯：
　　 drowsy[ˈdrauzi]
　　 a.昏昏欲睡的, 催眠的, (街、市等)沉寂的
　　 skim[skim]
　　 n.脫脂 v.撇去，去除;瀏覽，略讀
　　 impulse[ ˈimpʌls]
　　 v.推動(dòng);n.①推動(dòng);②沖動(dòng)，刺激
　　 [真題例句] As a result, the support for ambition as a healthy impulse (n.②), a quality to be admired and fixed in the mind of the young, is probably lower than it has ever been in the United States.[2000年閱讀5]
　　 [例句精譯] 因此，在美國(guó)，作為一種健康的沖動(dòng)，一種應(yīng)該令人稱(chēng)羨并扎根于青年人心靈的品質(zhì)的雄心，它所得到的支持也許比以往任何時(shí)期都低。
　　 obstacle[ˈɔbstəkl]
　　 n.障礙，妨礙，干擾
　　 [真題例句] The process is not the road itself, but rather the attitudes and feelings people have, their caution or courage, as they encounter new experiences and unexpected obstacles.[1995年閱讀2]
　　 [例句精譯] 成長(zhǎng)過(guò)程不是道路本身，而是當(dāng)遇到新情況或意外困難時(shí)所持的態(tài)度和情感，是慎重行事還是勇往直前。
　　 relaxation[ri:lækˈseiʃən]
　　 n.放松，松弛，娛樂(lè)
　　 [真題例句] (72) Children will play with dolls equipped with personality chips, computers with in-built personalities will be regarded as workmates rather than tools, relaxation will be in front of smell television, and digital age will have arrived.[2001年翻譯]
　　 [例句精譯] (72)兒童將與裝有個(gè)性化芯片的玩具娃娃玩耍，具有個(gè)性內(nèi)置的計(jì)算機(jī)將被視為工作伙伴而不是工具，人們將在氣味電視機(jī)前休閑，屆時(shí)數(shù)字化時(shí)代就來(lái)到了。
　　 enhance[inˈhɑ:ns]
　　 v.提高，增強(qiáng)
　　 [真題例句] 52. In the passage, which of the following is NOT included in the advantages of advertising?[1995年閱讀1]
　　 [C] Enhancing living standards.
　　 [例句精譯] 52�北疚闹�，廣告的優(yōu)點(diǎn)不包括下列哪項(xiàng)?
　　 [C] 提高生活水平。

　　背景常識(shí)介紹： 
　　"醫(yī)學(xué)之父"希波克拉底說(shuō)過(guò)："讓食物變成你的藥，讓藥變成你的食物。"作為一個(gè)生于公元前五世紀(jì)的希臘人，他的智慧遠(yuǎn)遠(yuǎn)超越了他所處的時(shí)代。如今，我們知道低脂肪而富含全麥、水果和蔬菜的飲食結(jié)構(gòu)能增強(qiáng)我們的免疫力，并能減少癌癥、心臟病和中風(fēng)的發(fā)病率。
　　但是，這些還不完全。新的證據(jù)顯示食品可能會(huì)影響健康人的思考和感覺(jué)方式。如果希波克拉底今天還在世的話，他也許會(huì)回顧他吃過(guò)的最后一頓飯，解釋他興奮(或憂傷)的心情。他可能還會(huì)改變自己的飲食習(xí)慣，使自己變得更幸福或更聰明。
　　參考譯文：
　　喝牛奶能讓你快樂(lè)嗎?吃魚(yú)能使你變聰明嗎?
　　設(shè)想一下你躺在床上，腦子里一片混亂。你輾轉(zhuǎn)反側(cè)，但總也睡不著。也許睡覺(jué)時(shí)吃點(diǎn)零食會(huì)有幫助。你應(yīng)當(dāng)吃什么呢?如果你的首選是威化餅或爆米花，那么一些專(zhuān)家就會(huì)說(shuō)你選對(duì)了。麥片、土豆、面食、餅干或米糕這些富含復(fù)合碳水化合物的食品會(huì)使人感到放松和困倦。
　　你選錯(cuò)了嗎?再試一次。假如天氣很糟，你忘了做家庭作業(yè)，而你的好朋友又對(duì)你大發(fā)雷霆。在你情緒低落之時(shí)，對(duì)你來(lái)說(shuō)什么是一劑良藥呢?一杯甜可樂(lè)或一塊糖可能會(huì)使你情緒很快高漲，但你的情緒又會(huì)很快地進(jìn)入低潮。更好的選擇是吃一些巴西胡桃(獲得更多的硒)，脫脂牛奶(獲得更多的鈣)，或菠菜沙拉(獲得更多的葉酸)。研究表明，上述三種營(yíng)養(yǎng)素都會(huì)使人們情緒高漲，擺脫憂慮。
　　再試一次吧。下午你有數(shù)學(xué)測(cè)驗(yàn)。你想要精力充沛，可你總是在午飯后感到昏昏欲睡。能使你精神飽滿地面對(duì)考試的最佳食品是炸薯?xiàng)l和奶昔，還是雞胸肉和低脂酸奶?如果你選中了高脂肪的炸薯?xiàng)l和奶昔，你就會(huì)感到非常懶散，很可能考砸了。高蛋白的雞肉和酸奶是較好的選擇。有些專(zhuān)家說(shuō)蛋白質(zhì)食品給人們提供能量。
　　食物如何影響情緒和思維?答案可能要到大腦和神經(jīng)系統(tǒng)的化學(xué)結(jié)構(gòu)中去找。被稱(chēng)為神經(jīng)遞質(zhì)的分子是化學(xué)信使。它們把神經(jīng)沖動(dòng)帶到神經(jīng)細(xì)胞之間的空隙中。神經(jīng)遞質(zhì)分子從一個(gè)神經(jīng)原釋放后，附著到另一個(gè)接受點(diǎn)，令神經(jīng)沖動(dòng)保持運(yùn)動(dòng)的狀態(tài)。
　　神經(jīng)沖動(dòng)能夠把周邊環(huán)境的信息帶到大腦中--例如，當(dāng)你腳趾被絆了一下時(shí)，你會(huì)感到疼。它們也能從反方向傳遞信息，比如說(shuō)從大腦到肌肉。這就是為什么當(dāng)障礙物產(chǎn)生疼痛的信號(hào)時(shí)，你就會(huì)躲開(kāi)障礙物，并且喊："哎喲!"
　　華盛頓大學(xué)的神經(jīng)科學(xué)家埃里克•查德勒說(shuō)："許多神經(jīng)遞質(zhì)是靠我們所吃的食物形成的。" 查德勒指出過(guò)多或過(guò)少地通過(guò)飲食攝入一種營(yíng)養(yǎng)素可以影響這些神經(jīng)遞質(zhì)的形成。例如，來(lái)自諸如酸奶、牛奶、香蕉和雞蛋的色氨酸會(huì)產(chǎn)生神經(jīng)遞質(zhì)的血清素。來(lái)自甜菜、杏仁、雞蛋、肉和谷物中的苯基丙胺酸會(huì)形成神經(jīng)遞質(zhì)的多巴胺。
　　我們已知的神經(jīng)遞質(zhì)有幾十種，實(shí)際存在的可能有幾百種。它們產(chǎn)生的效果取決于本身的數(shù)量和它們?cè)诖竽X中工作的位置。例如，神經(jīng)遞質(zhì)血清素被認(rèn)為會(huì)產(chǎn)生平靜、放松和滿足的感覺(jué)。治療情緒低落時(shí)，大夫就開(kāi)出一些能夠防止它返回(即進(jìn)入到釋放出它的神經(jīng)元中)的藥。至少在一些健康和情緒不低落的人當(dāng)中，碳水化合物食物似乎能夠促進(jìn)血清素的生成并能產(chǎn)生類(lèi)似效應(yīng)。查德勒說(shuō)："不同神經(jīng)遞質(zhì)之間的平衡幫助調(diào)節(jié)人的情緒。"
　　恰當(dāng)?shù)臓I(yíng)養(yǎng)能提高人的大腦思考能力。膽堿是一種類(lèi)似于維生素B的物質(zhì)。它存在于蛋黃、全麥、花生、牛奶、菜豆、肝、蠶豆、海鮮和黃豆中。大腦利用這種物質(zhì)生成神經(jīng)遞質(zhì)的乙酰膽堿。為了檢測(cè)膽堿對(duì)記憶和學(xué)習(xí)的影響，麻省理工學(xué)院的研究者們對(duì)大學(xué)生進(jìn)行了記憶測(cè)驗(yàn)。隨后，他們?cè)诒辉囼?yàn)者的飲食中增加膽堿的量，重新做了實(shí)驗(yàn)。從總體上來(lái)看，學(xué)生的記憶力有所提高，能夠更加容易地學(xué)會(huì)一系列不相關(guān)的單詞。