改变你的肠道菌群，吃什么很重要
如果你的新年决心是这一年过得更健康，可以考虑一下清理肠道。更新你肠道里的细菌及其微生物——被统称为肠道菌群——对你的健康而言，是一项长期的投资。
Trillions of microbial cells inhabit the human body, outnumbering human cells by 10 to one according to some estimates, and growing evidence suggests that the rich array of intestinal microbiota helps us process nutrients in the foods we eat, bolsters the immune system and does all sorts of odd jobs that promote sound health. A diminished microbial ecosystem, on the other hand, is believed to have consequences that extend far beyond the intestinal tract, affecting everything from allergies and inflammation, metabolic diseases like diabetes and obesity, even mental health conditions like depression and anxiety.
人体内寄居着数万亿微生物细胞，根据一些估计，其数量是人体细胞的十倍。有越来越多的证据显示，丰富的肠道菌群有助于我们处理食物中的营养物，增强免疫系统，还会做各种有益整体健康的零散工作。另一方面，微生物生态系统减弱所造成的后果则远不仅限于肠道，会影响方方面面，从过敏与炎症，到糖尿病和肥胖症等新陈代谢疾病，甚至影响抑郁和焦虑等心理健康状况。
Much of the composition of the microbiome is established early in life, shaped by forces like your genetics and whether you were breast-fed or bottle-fed. Microbial diversity may be further undermined by the typical high-calorie American diet, rich in sugar, meats and processed foods. But a new study in mice and people adds to evidence that suggests you can take steps to enrich your gut microbiota. Changing your diet to one containing a variety of plant-based foods, the new research suggests, may be crucial to achieving a healthier microbiome.
肠道菌群的大部分组成在生命的早期就建立了，其决定因素包括你的遗传基因，以及你是由母乳还是配方奶喂养。微生物的多样性可能会被包括大量糖、肉类和加工食品的典型高热量美国饮食进一步破坏。但一项以人和小鼠为实验对象的最新研究进一步验证，你可以采取一些措施来丰富自己的肠道菌群。新研究显示，将你的饮食改为以各色植物为主，对于获得更健康的菌群或许是至关重要的。
Altering your microbiome, however, may not be easy, and nobody knows how long it might take. That’s because the ecosystem already established in your gut determines how it absorbs and processes nutrients. So if the microbial community in your gut has been shaped by a daily diet of cheeseburgers and pepperoni pizza, for example, it won’t respond as quickly to a healthy diet as a gut shaped by vegetables and fruits that has more varied microbiota to begin with.
然而，要改变你的肠道菌群可能并不容易，没人知道这需要花多久时间。那是因为你的肠道里已经确立了生态系统，决定了它会如何吸收和处理营养物质。所以，如果你肠道里的微生物群落是由奶酪汉堡和帕帕罗尼披萨组成的日常饮食塑造而成，它产生反应的速度就不会像一个由蔬菜和水果塑造的肠道那么快，因为后者一开始就拥有更多样的微生物群。
“The nutritional value of food is influenced in part by the microbial community that encounters that food,” said Dr. Jeffrey Gordon, the senior author of the new paper and director of the Center for Genome Science and Systems Biology at the Washington University School of Medicine in St. Louis. Nutritional components of a healthy diet have to be viewed from “the inside out,” he said, “not just the outside in.”
“食物的营养价值一定程度上会被其遇到的微生物群落影响，”这篇新论文的第一作者、华盛顿大学圣路易斯医学院(Washington University School of Medicine in St. Louis)基因科学与系统生物学中心(Center for Genome Science and Systems Biology)主任杰弗里·戈登(Jeffrey Gordon)博士说。健康饮食的营养成分必须“从内而外”考量，他说，“而不只是由外而内”。
One of the questions the study set out to answer was how individuals with different diets respond when they try to improve their eating habits. The scientists harvested gut bacteria from humans, transplanted them into mice bred under sterile conditions, and then fed the mice either American-style or plant-based diets. The scientists then analyzed changes in the mice’s microbial communities.
这项研究着手回答的问题之一是，饮食不同的个人在试图改善自己饮食习惯时，分别会有什么样反应。科学家们从人体内提取肠道细菌，将它们移植到在无菌环境下养殖的小鼠体内，然后给小鼠提供美式饮食或植物为主的饮食。之后，科学家们再对小鼠体内微生物群落的变化进行分析。
Of interest, the scientists harvested the gut bacteria from people who followed sharply different diets. One group ate a fairly typical American diet, consuming about 3,000 calories a day, high in animal proteins with few fruits and vegetables. Some of their favorite foods were processed cheese, pepperoni and lunch meats.
值得关注的是，科学家们是从饮食习惯极为不同的两组人群里提取肠道细菌。其中一组是典型的美国日常饮食，每天摄入约含3000卡路里的食物，有大量动物蛋白，水果和蔬菜非常少。他们最喜欢的食物包括经过加工的奶酪、帕帕罗尼肠和午餐肉。
The other group consisted of people who were devotees of calorie restriction. They ate less than 1,800 calories a day and had meticulously tracked what they ate for at least two years, sticking to a mostly plant-based diet and consuming far less animal protein than the other group, a third fewer carbohydrates and only half the fat.
另一组由热衷于控制热量摄入的人组成。他们每天吃的食物热量少于1800卡路里，在过去至少两年内一直细致地监测自己的饮食，严格坚持大体以植物为主的饮食。与另一组相比，他们摄入的动物蛋白要少得多，摄入的碳水化合物少三分之一，脂肪也只有一半。
This calorie-restricted group, the researchers found, had a far richer and more diverse microbial community in the gut than those eating a typical American diet. They also carried several strains of “good” bacteria, known to promote health, that are unique to their plant-based diet. “Their choices as adults dramatically influenced their gut community,” said Nicholas W. Griffin of Washington University, the paper’s lead author.
研究人员发现，相比于遵循典型美国饮食的组，限制热量摄入组的肠道微生物群落数量要多得多，种类也多得多。他们还携带好几种被认为能增进健康的“有益”菌，那是他们以植物为主的饮食所特有的。“他们在成人阶段的选择，极大地改变了自己的肠道菌群，”这篇论文的主要作者、华盛顿大学的尼古拉斯·W·格里芬(Nicholas W. Griffin)说。
The study, published in Cell Host & Microbe, is not the first to report findings suggesting dietary shifts can induce persistent changes in a gut microbial community, said Dr. David A. Relman, a professor of medicine, microbiology and immunology at Stanford University, who was not involved in the current research. He noted that other studies had found even more profound effects.
与这项研究没有关联的斯坦福大学(Stanford)医学、微生物学和免疫学教授大卫·A·瑞尔曼(David A. Relman)表示，发表在《细胞宿主与微生物》(Cell Host & Microbe)杂志上的这项研究，不是第一篇提出转变饮食习惯能给肠道菌群带来持续改变的论文。他指出，其他一些研究甚至发现了更深刻的影响。
After the human microbiota was transplanted into the mice, the mice got to eat either like typical Americans or like the calorie restrictors.
在人的菌群被移植到实验鼠体内后，这些鼠要么吃类似典型美国饮食的食物，要么是类似限制热量摄入人群的饮食。
Mice that had a microbiota conditioned by the typical American diet had a weaker response to the plant-based diet. Their microbial communities didn’t increase and diversify as much. “They all responded in a predictable direction, but with not as great a magnitude,” said Dr. Griffin.
由典型美国饮食喂养的鼠，其肠道菌群对植物为主的饮食反应更弱。它们的微生物群落的数量和种类没有同等程度的增长。“它们都是朝着可预见的方向反应，但程度没有另一组那么大，”格里芬说。
Another aspect of the study suggests the company you keep may also enrich your gut microbiota — at least in mice. At first the animals were kept in separate cages. Then, when they were housed together, the microbes from the communities conditioned by plant diets made their way into the American-diet microbiome.
另一方面，这项研究也显示，你的同伴也会丰富你的肠道菌群——至少在小鼠中是如此。一开始，这些小鼠被关在单独的笼子里。然后，当它们被养在一起时，由植物类饮食产生的菌群便进入了由美式饮食塑造的菌群内。
It’s not clear how that translates to humans: Mice eat one another’s droppings when they live together, so they easily share the bacterial wealth. Still, it’s possible humans have other ways of sharing bacteria, Dr. Griffin said. “We know from previous work and other studies that spouses who live together will develop microbial communities that are similar to each other,” he said.
目前还不清楚在人体中会有怎样的表现：小鼠养在一起的时候会吃彼此的粪便，所以很容易交换菌群。不过，格里芬表示，人类有可能通过其他方式交换菌群。“根据之前的工作和研究，我们知道生活在一起的夫妻会发展出彼此类似的菌群，”他说。
Perhaps the best way to cultivate a healthier microbiome is to eat more fiber by consuming more fruit, vegetables, whole grains, legumes, and nuts or seeds, said Meghan Jardine, a registered dietitian who was not involved in the current study but has published articles on promoting a healthy microbiota. (She is also affiliated with the Physicians Committee for Responsible Medicine, which recommends a plant-based diet.) She urges people to aim for 40 to 50 grams of fiber daily, well above levels recommended by most dietary guidelines.
注册营养师梅根·贾丁(Meghan Jardine)表示，培育更健康菌群的最佳方式，或许是通过吃更多水果、蔬菜、全谷物、豆类、坚果或植物种子来摄入更多纤维。梅根与这项研究没有关联，但她发表过一些倡导健康菌群的文章。(她还是推荐植物性饮食的负责任医疗医师委员会[Physicians Committee for Responsible Medicine]的成员。)她极力主张人们努力做到每天摄入40至50克纤维，高于大多数饮食指南建议的水平。
“When you look at populations that eat real food that’s high in fiber, and more plant-based foods, you’re going to see they have a more robust microbiota, with more genetic diversity, healthier species and fewer pathogenic bacteria living in the gut,” she said.
“你观察一下吃真正的食物，也就是坚持高纤维、更多以植物为主饮食的人群，就会发现他们肠道内的菌群更有活力，有更强的遗传多样性，种类更健康，致病菌更少，”她说。
