CHILDREN have a lot to contend with these days, not least a tendency for their pushy parents to force-feed them omega-3 oils at every opportunity. These are supposed to make children brainier, so they are being added to everything from bread, milk and pasta to baby formula and vitamin tablets. But omega-3 is just the tip of the nutritional iceberg; many nutrients have proven cognitive effects, and do so throughout a person’s life, not merely when he is a child. 

    現在的孩子們與父母親的沖突很多，其中之一就是他們性急的父母親不放過任何機會強迫他們吃歐米伽-3。人們認為補充歐米伽-3能使孩子更聰明，因此幾乎所有的食品（面包、牛奶、意大利面、嬰兒奶粉以及維生素）中都添加了這種營養品。但是，歐米伽-3僅僅是營養品冰山的一角，許多其它的營養品也具有益智效果，而且這些營養品能在整個人的一生中都起作用，而不僅僅局限在兒童時期。

    Fernando Gómez-Pinilla, a fish-loving professor of neurosurgery and physiological science at the University of California, Los Angeles, believes that appropriate changes to a person’s diet can enhance his cognitive abilities, protect his brain from damage and counteract the effects of ageing. Dr Gómez-Pinilla has been studying the effects of food on the brain for years, and has now completed a review, just published in Nature Reviews Neuroscience, that has analysed more than 160 studies of food’s effect on the brain. Some foods, he concludes, are like pharmaceutical compounds; their effects are so profound that the mental health of entire countries may be linked to them. 

    費爾南多•戈麥斯-皮尼拉是加利福利亞大學洛杉磯分校的一名神經外科與生理科學教授，這位愛吃魚的教授認為適當改變一個人的飲食習慣能提高他的認知能力、保護他的大腦免收損傷以及延緩衰老。戈麥斯-皮尼拉博士研究食物對大腦的影響已有多年，他最近剛剛寫完一篇研究綜述并發表在《自然評論神經科學》雜志上。在這篇研究綜述中，戈麥斯-皮尼拉博士對160多項有關食物對大腦的影響的研究進行了綜合分析，他認為有些食物就像藥品一樣，它們的影響非常深刻以至于整個國家的心理健康都和這些食物相關。

    Last year, for example, the Lancet published research showing that folic-acid supplements—sometimes taken by pregnant women—can help those between 50 and 70 years old ward off the cognitive decline that accompanies ageing. In a study lasting three years, Jane Durga, of Wageningen University in the Netherlands, and her colleagues found that people taking such supplements did better on measures of memory, information-processing speed and verbal fluency. That, plus evidence that folate deficiency is associated with clinical depression, suggests eating spinach, orange juice and Marmite, which are all rich in folic acid.

    比如去年《柳葉刀》雜志發表的一項研究表明，葉酸（有時候孕婦服用）能幫助50-70歲的人抵抗由于年齡增長帶來的認知能力減退。在一項持續3年的研究中，來自荷蘭瓦格寧根大學的簡•德伽和她的同事發現服用葉酸的人在記憶力、信息處理速度以及語言流暢性方面要表現得更好。另外，有證據表明葉酸缺乏與臨床性抑郁癥有關。綜合上述研究結果，我們應該多吃那些富含葉酸的食物，比如菠菜、橙汁和Marmite（譯者注：一種食品的商標名稱，這種食品一般涂在面包上吃）。

    Another suggestion from Dr Gómez-Pinilla’s review is that people should eat more antioxidants. That idea is not new. Antioxidants are reckoned by many to protect against the general effects of ageing. Vitamin E, for example, which is found in vegetable oils, nuts and green leafy vegetables, has been linked (in mice) with the retention of memory into old age, and also with longer life. 

    戈麥斯-皮尼拉博士研究的另外一個建議就是人們應該吃富含抗氧劑的食物。這個觀點本身并不新，很多人都知道抗氧劑能延緩衰老。比如對老鼠的實驗表明，維生素E（植物油、堅果和綠色葉類蔬菜中含有維生素E）與記憶力的長期保持以及長壽有關。

    Dr Gómez-Pinilla, however, gives the antioxidant story a particular twist. The brain, he observes, is peculiarly susceptible to oxidative damage. It consumes a lot of energy, and the reactions that release this energy also generate oxidising chemicals. Moreover, brain tissue contains a great deal of oxidisable material, particularly in the fatty membranes surrounding nerve cells. 

    但是戈麥斯-皮尼拉博士也指出了抗氧劑的兩面性。他發現大腦非常易于受到氧化性的損傷。大腦所需要的大量能量來源于一些化學反應，這些化學反應釋放大腦需要的能量的同時也產生氧化性化學物質。而且大腦組織含有大量的易氧化物質，尤其存在于環繞神經細胞的脂肪膜里面。

    That suggests, among other things, the value of a diet rich in berries. These have been shown to have strong antioxidant effects, though only a small number of their constituents have been evaluated in detail. One group that has been evaluated, the polyphenols, has been shown in rodents to reduce oxidative damage and to boost the ability to learn and retain memories. In particular, these chemicals affect changes in response to different types of stimulation in the hippocampus (a part of the brain that is crucial to the formation of long-term memories, and which is the region most affected by Alzheimer’s disease). Another polyphenol, curcumin, has also been shown to have protective effects. It reduces memory deficits in animals with brain damage. It may be no coincidence that in India, where a lot of curcumin is consumed (it is the substance that makes turmeric yellow), Alzheimer’s disease is rarer than elsewhere.

    鑒于此以及其它的原因，富含苺類的飲食就顯得有益。苺類水果具有強的抗氧化效果，但是人們僅對其少數成分進行了詳細分析。多酚是其中被分析的一組成分，從嚙齒類動物來看，多酚能降低氧化性損傷以及提高它們學習和保持記憶的能力。尤其特別的是，在海馬體中（海馬體是大腦的一部分，它對長期記憶的形成起關鍵作用，老年癡呆癥對海馬體的影響最大）不同的刺激帶來相應的變化，多酚就能影響這些變化。另外一種名叫姜黃素的多酚也具有保護作用。對于大腦受損的動物，姜黃素能降低這些動物的記憶缺失。印度人吃很多的姜黃素（姜黃素就是用來做姜黃的物質），印度人患老年癡呆癥的人比其它地方的人少得多，這或許不是一個巧合。

    Though the way antioxidants work in the brain is not well known, Dr Gómez-Pinilla says it is likely they protect the synaptic membranes. Synapses are the junctions between nerve cells, and their action is central to learning and memory. But they are also, he says, the most fragile parts of the brain. And many of the nutrients associated with brain function are known to affect transmission at the synapses.

    雖然人們對抗氧劑在大腦內的作用機理還不是很清楚，但是戈麥斯-皮尼拉博士認為它們可能起到保護神經節膜的作用。神經節是神經細胞之間的結合點，它們對學習和記憶起至關重要的作用。但是它們也是大腦中最脆弱的部分。人們知道，許多與腦功能有關的營養成分能影響神經節之間的信號傳輸。

    An omega-3 fatty acid called docosahexaenoic acid (DHA), for example, provides membranes at synaptic regions with “fluidity”—the capacity to transport signals. It also provides “plasticity”—a synapse’s capacity to change. Such changes are the basis of memory. Since 30% of the fatty constituents of nerve-cell membranes are DHA molecules, keeping your DHA levels topped up is part of having a healthy brain. Indeed, according to the studies reviewed by Dr Gómez-Pinilla, the benefits of omega-3s include improved learning and memory, and resistance to depression and bipolar disorder, schizophrenia, dementia, attention-deficit disorder and dyslexia. 

    例如一種叫做二十二碳六烯酸（DHA）的歐米伽-3脂肪酸，提供給神經節膜“流動性”（神經節傳輸信號的能力）。它也提供給神經節膜“彈性”（神經節變化的能力）。這些變化是記憶的基礎。因為神經細胞膜的脂肪成分30%都是DHA分子，因此保持高水平DHA有利于獲得一個健康的大腦。根據戈麥斯-皮尼拉博士綜述中的研究，歐米伽-3的益處包括提高學習和記憶能力，抵抗抑郁癥、雙極性情感疾病、精神分裂癥、精神病、注意力缺乏癥以及閱讀障礙。

    Omega-3s are found in oily fish such as salmon, as well as in walnuts and kiwi fruit, and there is a strong negative correlation between the extent to which a country consumes fish and its levels of clinical depression. On the Japanese island of Okinawa, for example, people have a strikingly low rate of mental disorder—and Okinawans are notable fish eaters, even by the standards of a piscivorous country like Japan. In contrast, many studies suggest that diets which are rich in trans- and saturated fatty acids, such as those containing a lot of deep-fried foods and butter, have bad effects on cognition. Rodents put on such diets show declines in cognitive performance within weeks. 

    含油豐富的魚類中含有歐米茄-3，比如三文魚、核桃，獼猴桃中也含有歐米茄-3，而且在一個國家中，人們吃魚越多，這個國家的臨床抑郁癥發病率越低。例如在日本的沖繩島，這里的人們心理疾病發病率非常低，而沖繩島的居民以吃魚聞名，就是按照日本這個以吃魚著稱的國家的標準來看，沖繩島居民的嗜魚也是格外有名的。相反，許多研究表明含大量順式以及飽和脂肪酸的飲食（比如那些含有大量深度油炸食品和黃油的飲食）對認知能力產生壞的影響。嚙齒類動物食用這樣的飲食后，幾周內便表現出認知能力下降。

    In the past few years, several studies have looked at the effect of adding omega-3s to people’s diets—particularly those of children. One such, carried out in the British city of Durham, was controversial in that it was funded by a maker of children’s omega-3 supplements and did not include a control group being given a placebo. Despite the publicity this study has received, Ben Goldacre, author of a book called “Bad Science” that includes an investigation of it, says the results will not be released. 

    在過去幾年里，人們對飲食中添加歐米茄-3的影響進行了幾項研究——尤其是研究在兒童的飲食中添加歐米茄-3產生的影響。 其中一項研究在英國的達勒姆市進行，不過這項研究因為兩個原因導致了爭議：首先這項研究的資助來自于一家生產供兒童食用的歐米茄-3的制造商，其次這項研究沒有引入控制組（控制組服用安慰劑）。盡管這項研究引起了公眾的關注，本•高德卡說這項研究的結果不會被公布出來。本•高德卡是“《壞科學》”的作者，在這本書中記載了有關對這項研究的調查。

    Work by other researchers, however, has suggested such supplements do improve the performance and behaviour of school-age children with specific diagnoses such as dyslexia, attention-deficit disorder and developmental co-ordination disorder. Moreover, although more work is needed to elucidate the effects of omega-3s on healthy school-age children, Dr Gómez-Pinilla says that younger children whose mothers took fish-oil supplements (which contain omega-3s) when they were pregnant and while they were breast-feeding do show better cognitive performance than their unsupplemented contemporaries.

    但是，其他研究者的工作表明，對于那些患有諸如閱讀障礙、注意力缺乏癥以及發展性協調障礙的學齡兒童來說，歐米茄-3確實能提高他們的學習成績以及改善他們的行為方式。雖然，歐米茄-3對于健康學齡兒童的影響還有待研究，但是，戈麥斯-皮尼拉博士說，母親在懷孕和哺乳期間服用含歐米茄-3的魚油營養品的孩子們，確實在認知能力上要比那些母親在懷孕和哺乳期間不服用含歐米茄-3的魚油營養品的孩子們表現得更好。

    Eating well, then, is one key to a healthy brain. But a word of warning—do not overeat. This puts oxidative stress on the brain and risks undoing all the good work those antioxidants have been up to. For those who would like a little practical guidance, The Economist has some suggestions for dinner (see menu). So why not put the Nintendo brain trainer away tonight, and eat your way to intelligence instead? 

    所以，吃得好是擁有健康大腦的關鍵之一。但是請記住一句忠告：過猶不及。過度飲食會導致大腦處于氧化性壓力之下，這樣的話那些抗氧劑能帶來的好處很可能就被這種壓力抵消了。如果你想要一些實際的指導，《經濟學人》可以給你的晚餐一些建議（請看菜單）。所以今天晚上何不停下手里的任天堂游戲，而是享受一頓益智的晚餐？