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.
考研词汇：
drowsy[ˈdrauzi]
a.昏昏欲睡的, 催眠的, (街、市等)沉寂的
skim[skim]
n.脱脂 v.撇去，去除;浏览，略读
impulse[ ˈimpʌls]
v.推动;n.①推动;②冲动，刺激
[真题例句] 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年阅读5]
[例句精译] 因此，在美国，作为一种健康的冲动，一种应该令人称羡并扎根于青年人心灵的品质的雄心，它所得到的支持也许比以往任何时期都低。
obstacle[ˈɔbstəkl]
n.障碍，妨碍，干扰
[真题例句] 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年阅读2]
[例句精译] 成长过程不是道路本身，而是当遇到新情况或意外困难时所持的态度和情感，是慎重行事还是勇往直前。
relaxation[ri:lækˈseiʃən]
n.放松，松弛，娱乐
[真题例句] (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年翻译]
[例句精译] (72)儿童将与装有个性化芯片的玩具娃娃玩耍，具有个性内置的计算机将被视为工作伙伴而不是工具，人们将在气味电视机前休闲，届时数字化时代就来到了。
enhance[inˈhɑ:ns]
v.提高，增强
[真题例句] 52. In the passage, which of the following is NOT included in the advantages of advertising?[1995年阅读1]
[C] Enhancing living standards.
[例句精译] 52本文中，广告的优点不包括下列哪项?
[C] 提高生活水平。
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