英国新闻听力 Omega-3脂肪酸与学习能力的关系（在线收听）

HOST: In 2005, Physiologist Alex Richardson set up a detective hypothesis that the low level of omega-3 were detrimental. She devised a clinical trial amongst a group of school children suffering mood and behavioral disorders. She believed they might benefit from food supplements. The trial, the Oxford Durum study would chart that progress.

ALEX RICHARDSON: What we did was to take almost 120 children from British primary schools that they range of 5, or 6 up to 11, and we gave them either a fatty acid supplement or a placebo demi-pill. And while we found with in three months there was a significant improvement in the behavior, but also in the reading and the spelling progress, the literacy skills of the children who got the fatty acid supplements.

HOST: Were these children just regular normal, healthy children? Or were these kids who have been struggling at school for whatever reason?

ALEX RICHARDSON: In fact, they all might try criterion for a condition called developmental coordination disorder, dyspepsia as it's sometimes known, it also overlaps very strongly with birth dyspepsia, and a tension-deficit hypo-activity type problems.

HOST: Are you saying that after three months on supplement of the two key omega-3 fatty acid, you said the group who were taking them; there were improvements in their abilities, but by how much?

ALEX RICHARDSON: Well, their reading progress of those who got the active supplements improved by nine months in a three-month period. In the controlled group, they just made normal progress, their reading improved three month in three months, which is exactly what you expected from these age-norm tests. In spelling, the children who got the supplements made six-month progress in three, so two or three times the normal rate of progress from perfectly healthy normally performing children was what we saw.

HOST: This fact, this is because the children weren't having enough omega-3 of these particular types in their diet to starve at all. Did the extra omega-3 they were given, you know, help leave it the effects of different causes on their learning abilities?

ALEX RICHARDSON: We won't able in the study that had taken our blood samples to measure omega-3 in blood as has been done with some mental health patients, nor were we able to get a dairy record. We don't yet know that this is what we need to know, what intake is optimal for the brain.

HOST: But might it not be the case that nutrients other than the omega-3 are equally important? If scientists don't know the optimal level of this central fatty acid, how could they be so sure that their proof is so critical? They can't, but neurophysiologist professor John Stein of Oxford University believes they have good reason to feel confident.

JOHN STEIN: You have to start off with a theoretical basis, with the reason that I've got from chart derives from the importance of the fissions in your nerve membranes and it makes very plausible, physiological sense. Now you've got to have that sort of prior evidence in order to really make in worthwhile to go for a trial, in my opinion. I mean, you could just work your way through thousands of things doing trials and cost a fortune and it would be extremely uneconomic. 

主持人：2005年，生理学者亚力克斯·理查森提出了一个试探性的假设，她认为缺少omega-3脂肪酸是对人体有害的。她设计了一个临床试验，实验对象是一群深受行为和情绪混乱折磨的在校学生。她相信食品补给品对这种疾病有积极作用。牛津硬质小麦研究小组会将此项试验的进展绘制成图表。

亚力克斯·理查森：我们从英国的一所小学里挑选了大约120个学生。这些小孩的年龄分布在5岁，6岁到11岁不等。我们将他们分成两组，给其中一组服用了脂肪酸，另一组是镇静剂。我们发现，在接下来的三个月里，服用脂肪酸补给品的学生不仅在行为有了显著的变化，他们的阅读能力，拼写能力以及读写能力都有很大的提高。

主持人：这些孩子本身是正常，健康的？还是他们因为别的什么原因才在学校表现失常呢？

亚力克斯·理查森：事实上，他们的症状被称为在一定条件下的发展性协调障碍。比如我们知道的消化不良，它通常与先天性的消化不良有很多共同点，与紧张多动症类似。

主持人：你是说在三个月后，那组服用含有两组关键omega-3脂肪酸成分的脂肪酸的学生行为都有所提高，提高程度都有多少呢？

亚力克斯·理查森：服用活性补给品组的学生，阅读水平在三个月内提高的程度相当于正常过程中九个月才能到达的程度。服用安慰剂组的学生，只达到了正常的程度，阅读水平在三个月内就只达到三个月的水平。这就是我们想在这个实验中得到的结果。在拼写方面，服用补给品的学生在三个月内就达到了在常情况下普通学生需要六个月才能取得的进步，也就是提高速度是正常情况的两到三倍。

主持人：事实说明，就算孩子没有摄取足够的这种特别类型的omega-3脂肪酸，他们也不至于饿死。你知道，当他们摄取份外的omega-3脂肪酸时，会对他们的学习能力产生不同的影响吗？

亚力克斯·理查森：我们不能在这项研究中采集血液样品去测量omega-3脂肪酸在血液中的含量，像以前我们曾经对精神状况正常的人这样试验过的那样，而且我们也无法每天做记录。因此，我们现在还无法得知，但是我们需要弄清楚，大脑要摄入多少omega-3脂肪酸才能达到最佳状态。

主持人：但是，在这个案例里，有没有可能起作用的是那些营养元素而不是omega-3脂肪酸，如果科学家不知道这种中枢脂肪酸的最佳状态，他们如何能确定他们的证据是关键的呢？他们是无法做到，但牛津大学的神经生理学教授约翰·斯坦相信他们有足够的证据支撑他们的论点。

约翰·斯坦：你必须从理论依据开始，因为我从由神经膜裂变的意义得出的图表显示，人的神经膜会带来似是而非的生理感觉。我认为，现在你已经得到了那种为做一次真正有价值的试验的重要证据。我是说，你可以通过其它成百上千种方式来做试验碰碰运气，但没有理论基础的试验花费甚大，很不经济。