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. 

    现在的孩子们与父母亲的冲突很多，其中之一就是他们性急的父母亲不放过任何机会强迫他们吃欧米伽-3。人们认为补充欧米伽-3能使孩子更聪明，因此几乎所有的食品（面包、牛奶、意大利面、婴儿奶粉以及维生素）中都添加了这种营养品。但是，欧米伽-3仅仅是营养品冰山的一角，许多其它的营养品也具有益智效果，而且这些营养品能在整个人的一生中都起作用，而不仅仅局限在儿童时期。

    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. 

    费尔南多•戈麦斯-皮尼拉是加利福利亚大学洛杉矶分校的一名神经外科与生理科学教授，这位爱吃鱼的教授认为适当改变一个人的饮食习惯能提高他的认知能力、保护他的大脑免收损伤以及延缓衰老。戈麦斯-皮尼拉博士研究食物对大脑的影响已有多年，他最近刚刚写完一篇研究综述并发表在《自然评论神经科学》杂志上。在这篇研究综述中，戈麦斯-皮尼拉博士对160多项有关食物对大脑的影响的研究进行了综合分析，他认为有些食物就像药品一样，它们的影响非常深刻以至于整个国家的心理健康都和这些食物相关。

    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《柳叶刀》杂志发表的一项研究表明，叶酸（有时候孕妇服用）能帮助50-70岁的人抵抗由于年龄增长带来的认知能力减退。在一项持续3年的研究中，来自荷兰瓦格宁根大学的简•德伽和她的同事发现服用叶酸的人在记忆力、信息处理速度以及语言流畅性方面要表现得更好。另外，有证据表明叶酸缺乏与临床性抑郁症有关。综合上述研究结果，我们应该多吃那些富含叶酸的食物，比如菠菜、橙汁和Marmite（译者注：一种食品的商标名称，这种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. 

    戈麦斯-皮尼拉博士研究的另外一个建议就是人们应该吃富含抗氧剂的食物。这个观点本身并不新，很多人都知道抗氧剂能延缓衰老。比如对老鼠的实验表明，维生素E（植物油、坚果和绿色叶类蔬菜中含有维生素E）与记忆力的长期保持以及长寿有关。

    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. 

    但是戈麦斯-皮尼拉博士也指出了抗氧剂的两面性。他发现大脑非常易于受到氧化性的损伤。大脑所需要的大量能量来源于一些化学反应，这些化学反应释放大脑需要的能量的同时也产生氧化性化学物质。而且大脑组织含有大量的易氧化物质，尤其存在于环绕神经细胞的脂肪膜里面。

    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.

    鉴于此以及其它的原因，富含苺类的饮食就显得有益。苺类水果具有强的抗氧化效果，但是人们仅对其少数成分进行了详细分析。多酚是其中被分析的一组成分，从啮齿类动物来看，多酚能降低氧化性损伤以及提高它们学习和保持记忆的能力。尤其特别的是，在海马体中（海马体是大脑的一部分，它对长期记忆的形成起关键作用，老年痴呆症对海马体的影响最大）不同的刺激带来相应的变化，多酚就能影响这些变化。另外一种名叫姜黄素的多酚也具有保护作用。对于大脑受损的动物，姜黄素能降低这些动物的记忆缺失。印度人吃很多的姜黄素（姜黄素就是用来做姜黄的物质），印度人患老年痴呆症的人比其它地方的人少得多，这或许不是一个巧合。

    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.

    虽然人们对抗氧剂在大脑内的作用机理还不是很清楚，但是戈麦斯-皮尼拉博士认为它们可能起到保护神经节膜的作用。神经节是神经细胞之间的结合点，它们对学习和记忆起至关重要的作用。但是它们也是大脑中最脆弱的部分。人们知道，许多与脑功能有关的营养成分能影响神经节之间的信号传输。

    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. 

    例如一种叫做二十二碳六烯酸（DHA）的欧米伽-3脂肪酸，提供给神经节膜“流动性”（神经节传输信号的能力）。它也提供给神经节膜“弹性”（神经节变化的能力）。这些变化是记忆的基础。因为神经细胞膜的脂肪成分30%都是DHA分子，因此保持高水平DHA有利于获得一个健康的大脑。根据戈麦斯-皮尼拉博士综述中的研究，欧米伽-3的益处包括提高学习和记忆能力，抵抗抑郁症、双极性情感疾病、精神分裂症、精神病、注意力缺乏症以及阅读障碍。

    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. 

    含油丰富的鱼类中含有欧米茄-3，比如三文鱼、核桃，猕猴桃中也含有欧米茄-3，而且在一个国家中，人们吃鱼越多，这个国家的临床抑郁症发病率越低。例如在日本的冲绳岛，这里的人们心理疾病发病率非常低，而冲绳岛的居民以吃鱼闻名，就是按照日本这个以吃鱼著称的国家的标准来看，冲绳岛居民的嗜鱼也是格外有名的。相反，许多研究表明含大量顺式以及饱和脂肪酸的饮食（比如那些含有大量深度油炸食品和黄油的饮食）对认知能力产生坏的影响。啮齿类动物食用这样的饮食后，几周内便表现出认知能力下降。

    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. 

    在过去几年里，人们对饮食中添加欧米茄-3的影响进行了几项研究——尤其是研究在儿童的饮食中添加欧米茄-3产生的影响。 其中一项研究在英国的达勒姆市进行，不过这项研究因为两个原因导致了争议：首先这项研究的资助来自于一家生产供儿童食用的欧米茄-3的制造商，其次这项研究没有引入控制组（控制组服用安慰剂）。尽管这项研究引起了公众的关注，本•高德卡说这项研究的结果不会被公布出来。本•高德卡是“《坏科学》”的作者，在这本书中记载了有关对这项研究的调查。

    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，对于那些患有诸如阅读障碍、注意力缺乏症以及发展性协调障碍的学龄儿童来说，欧米茄-3确实能提高他们的学习成绩以及改善他们的行为方式。虽然，欧米茄-3对于健康学龄儿童的影响还有待研究，但是，戈麦斯-皮尼拉博士说，母亲在怀孕和哺乳期间服用含欧米茄-3的鱼油营养品的孩子们，确实在认知能力上要比那些母亲在怀孕和哺乳期间不服用含欧米茄-3的鱼油营养品的孩子们表现得更好。

    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，吃得好是拥有健康大脑的关键之一。但是请记住一句忠告：过犹不及。过度饮食会导致大脑处于氧化性压力之下，这样的话那些抗氧剂能带来的好处很可能就被这种压力抵消了。如果你想要一些实际的指导，《经济学人》可以给你的晚餐一些建议（请看菜单）。所以今天晚上何不停下手里的任天堂游戏，而是享受一顿益智的晚餐？