抹茶拿铁真的比红茶更健康吗?【考研英语经济学人双语精读】

Is a matcha latte better for you than a builder’s brew?

AFTER WATER, tea is the world’s most popular beverage. Some drinkers may be attracted by its warmth on a cold day, others by the cobweb-clearing promise of its caffeine. But tea possesses health benefits, too. For one, it contains L-theanine, an amino acid thought to boost dopamine and serotonin, brain chemicals that lift mood. Tea is also rich in antioxidants that researchers have linked to reduced risks of developing cardiovascular disease and dementia.

除水之外，茶是全球最受欢迎的饮品。有人喜欢它在寒冷天气里带来的温暖，有人则被咖啡因“扫清脑中迷雾”的提神效果所吸引。但茶的好处不止于此。首先，它含有 L-茶氨酸——一种被认为能促进多巴胺和血清素分泌的氨基酸，而这两种大脑化学物质有助于改善情绪。此外，茶还富含抗氧化物，研究人员已将其与心血管疾病和痴呆风险的降低联系起来。

Black teas (such as Assam and Darjeeling) account for more than two-thirds of consumption. Worldwide sales of green teas (such as matcha), however, have been steadily climbing in recent years, buoyed in part by reports that these may be healthier. But what does the science say?

在茶的消费中，红茶（如阿萨姆茶和达尔杰林茶）占据了三分之二以上。然而，近年来绿茶（如抹茶）的全球销量持续增长，部分原因是人们普遍认为它们更健康。那么，科学研究给出的答案是什么？

One striking paper was published in Molecules in 2019. Its authors analysed data on 3,349 individuals aged 50 and up. After adjusting for smoking, coffee consumption and other variables, they found that those who drank green tea scored higher than black-tea drinkers on a “successful ageing” health index that assigned scores for such things as body weight, health and levels of physical and social activity.

2019年发表在《Molecules》上的一项研究颇为引人注目。研究人员分析了3349名50岁及以上人群的数据。在控制了吸烟、咖啡摄入等因素后，他们发现，与喝红茶的人相比，喝绿茶的人在“成功老龄化”健康指数上的得分更高。该指数涵盖了体重、总体健康状况，以及身体和社会活动水平等指标。

One reason for this might be their respective L-theanine content. Green tea contains nearly 28% more per cup than black tea does, a study found in 2016. In addition to promoting soothing brain chemicals, L-theanine has been shown by recordings of brain activity to amplify alpha brain waves—electrical oscillations that seem to sharpen mental focus without causing jitters. When consumed regularly, L-theanine seems to reduce stress and improve sleep. The benefits appear to increase with the daily dose, at least up to about 200mg, roughly the amount in eight cups of green tea.

这种差异的一个原因，可能在于L-茶氨酸含量的不同。2016年的一项研究发现，绿茶每杯所含的L-茶氨酸比红茶高出近28%。除了促进令人放松的大脑化学物质外，脑电活动记录还显示，L-茶氨酸能够增强 α脑波——这类电活动似乎可以在不引起紧张不安的情况下，提高专注力。规律摄入L-茶氨酸似乎还能减轻压力、改善睡眠，其益处会随着每日摄入量增加而增强，至少在 200毫克/天以内如此——这大约相当于 8杯绿茶的含量。

Two studies bear this out. In one, published in Nutrients in 2019, 30 Japanese adults of all ages took 200mg of L-theanine daily for four weeks. They also spent another four weeks on a placebo. In addition to increasing verbal fluency and cognitive function, the supplements “significantly” improved sleep and reduced symptoms of anxiety and depression compared to placebo, the researchers wrote. In another trial, reported in the Journal of Medicinal Food in 2021, 26 Japanese volunteers aged 50 to 69 were given a supplement with only half as much L-theanine. After a single dose, they performed notably better on tests of memory and reaction speeds than participants who had popped a placebo.

两项研究印证了这一点。第一项发表于2019年的《Nutrients》，研究对象为30名不同年龄段的日本成年人。他们连续四周每天服用200毫克L-茶氨酸，另有四周服用安慰剂。研究人员写道，与安慰剂相比，L-茶氨酸补充剂不仅提高了语言流畅性和认知功能，还“显著”改善了睡眠，并减轻了焦虑和抑郁症状。第二项试验发表于2021年的《Journal of Medicinal Food》，26名50至69岁的日本志愿者服用了剂量仅为前者一半的L-茶氨酸补充剂。仅一次服用后，他们在记忆力和反应速度测试中的表现就明显优于服用安慰剂的人。

Green teas have also been shown to contain roughly a fifth more antioxidants than black ones. Although both are made from the leaves of the same plant, Camellia sinensis, black tea leaves are dried, crushed and left to darken as their compounds slowly react with oxygen. This oxidation converts many of tea’s antioxidants into new molecules. According to a paper in the International Journal of Molecular Sciences in 2020, one antioxidant left behind in green tea eases inflammation, and helps kill off damaged cells, possibly reducing risks of cardiovascular disease and cancers of the respiratory and digestive systems.

研究还显示，绿茶中的抗氧化物含量大约比红茶高出五分之一。尽管两者都来自同一种植物——茶树（Camellia sinensis），但红茶叶在加工过程中会被干燥、揉碎，并暴露在空气中逐渐变深色，其化合物与氧气缓慢反应，发生氧化。这一过程会将茶中的许多抗氧化物转化为新的分子。2020年发表于《International Journal of Molecular Sciences》的一篇论文指出，绿茶中保留下来的一种抗氧化物可以缓解炎症、清除受损细胞，从而可能降低心血管疾病以及呼吸系统和消化系统癌症的风险。

Black tea is not without its own benefits. It is richer than green tea in beneficial compounds such as theaflavins and thearubigins. Theaflavins reduce the body’s absorption of cholesterol, a fatty molecule that can contribute to arterial plaque, while both theaflavins and thearubigins protect cells from oxidative and inflammatory damage. By all means make your next order a matcha, but do not chuck those black-tea bags just yet.

当然，红茶也有自身的健康优势。它比绿茶更富含茶黄素（theaflavins）和茶红素（thearubigins）等有益化合物。茶黄素能减少人体对胆固醇这种脂肪分子的吸收，而茶黄素和茶红素都能保护细胞免受氧化和炎症损伤。所以，尽管下次点一杯抹茶完全没问题，但也别急着把那些红茶包扔掉。