The science of happiness has turned up evidence that food can make you happy. However, a lack of certain foods or at least some of their essential ingredients can actually make you sad.
A fatty acid called docosahexaenoic acid(DHA)is the most plentiful fat found in the brain.It’s an essential ingredient for brain structure. It’s also easy to get; two major sources of DHA are fish and shellfish. A study by the National Institutes of Health(NIH)uncovered a link between lack of DHA and an increase in the prevalence(患病率) of depression in the United States.
Other studies support the link the NIH found. One study turned up the fact that North American and European countries that don’t eat a lot of fish have 10 times the prevalence of depression in their populations than does Taiwan, where fish is a main course of the popular diet.
Strangely, while some foods have been shown to improve mood in the human brain, researchers have found that putting a limit on food intake can have an even more obvious effect on happiness. A hormone called ghrelin within the stomach heads over to the brain and tells it that it’s time to eat. When ghrelin is produced, you feel hungry. After you take food into the body, ghrelin production stops. When you don’t eat, however, ghrelin production continues and the hormone builds up in the brain. While the increased ghrelin will make your hunger last longer, researchers have found that the hormone also acts as a natural antidepressant(抗抑郁剂)．
Whether it’s psychological or physiological, it’s clear that foods have a powerful effect on our moods. It would appear that eating only nutrientpacked(富含营养的) foods that affect brain chemistry might be the best way to achieve happiness. But the occasional indulgence(放纵) should make you just as happy. Perhaps a healthy balance of nutritious foods and snacks can help keep the balance in a person’s mood best of all.
【解题导语】 本文是一篇说明文。让我们一起“吃”出快乐来！科学研究表明，饮食与人的情绪和心理有非常密切的关系。
1．What can we infer from the NIH’s finding?
A．Fish is rich in DHA.
B．Children who often eat fish tend to be smarter.
C．Enough intake of DHA helps prevent depression.
D．The number of Americans with depression is rising rapidly.
C 解析：推理判断题。由第二段可知，NIH的一项研究发现，DHA的不足与美国忧郁症的发病率上升之间存在联系，再结合第三段的支撑例证可推知：摄入充足的DHA有助于预防忧郁症。
2．What will happen if we limit food intake for a long time?
A．The feeling of hunger disappears.
B．We are likely to feel happy.
C．Ghrelin production stops.
D．Unhappiness will appear.
B 解析：推理判断题。由第四段第一句可知，尽管一些食物能够改善情绪，但是研究者发现控制食量对快乐的影响更大。结合本段最后一句While the increased ghrelin will make your hunger last longer, researchers have found that the hormone also acts as a natural antidepressant(抗抑郁剂). 可推知，长期控制食量可能会让我们快乐。
3．According to the author, what’s the best eating style to keep happy?
A．Eating DHArich foods.
B．Including fish in your daily meals.
C．Consuming nutrientpacked foods each day.
D．Combining nutritious foods and favorite snacks.
D 解析：细节理解题。由最后一段可知，a healthy balance of nutritious foods and snacks最有助于人们保持情绪的平衡。
4．Where does the text probably come from?
A．A science magazine.
B．A business report.
C．A research plan.
D．A news story.
A 解析：文章出处题。本文以研究结果为证，介绍了饮食对人的情绪的影响，属于健康类话题，最有可能出现在科学杂志上。
