改變你的腸道菌群，吃什么很重要

If you’re making resolutions for a healthier new year, consider a gut makeover. Refashioning the community of bacteria and other microbes living in your intestinal tract, collectively known as the gut microbiome, could be a good long-term investment in your health.

如果你的新年決心是這一年過得更健康，可以考慮一下清理腸道。更新你腸道里的細菌及其微生物——被統(tǒng)稱為腸道菌群——對你的健康而言，是一項長期的投資。

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.

人體內(nèi)寄居著數(shù)萬億微生物細胞，根據(jù)一些估計，其數(shù)量是人體細胞的十倍。有越來越多的證據(jù)顯示，豐富的腸道菌群有助于我們處理食物中的營養(yǎng)物，增強免疫系統(tǒng)，還會做各種有益整體健康的零散工作。另一方面，微生物生態(tài)系統(tǒng)減弱所造成的后果則遠不僅限于腸道，會影響方方面面，從過敏與炎癥，到糖尿病和肥胖癥等新陳代謝疾病，甚至影響抑郁和焦慮等心理健康狀況。

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.

腸道菌群的大部分組成在生命的早期就建立了，其決定因素包括你的遺傳基因，以及你是由母乳還是配方奶喂養(yǎng)。微生物的多樣性可能會被包括大量糖、肉類和加工食品的典型高熱量美國飲食進一步破壞。但一項以人和小鼠為實驗對象的最新研究進一步驗證，你可以采取一些措施來豐富自己的腸道菌群。新研究顯示，將你的飲食改為以各色植物為主，對于獲得更健康的菌群或許是至關(guān)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，要改變你的腸道菌群可能并不容易，沒人知道這需要花多久時間。那是因為你的腸道里已經(jīng)確立了生態(tài)系統(tǒng)，決定了它會如何吸收和處理營養(yǎng)物質(zhì)。所以，如果你腸道里的微生物群落是由奶酪漢堡和帕帕羅尼披薩組成的日常飲食塑造而成，它產(chǎn)生反應(yīng)的速度就不會像一個由蔬菜和水果塑造的腸道那么快，因為后者一開始就擁有更多樣的微生物群。

“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.”

“食物的營養(yǎng)價值一定程度上會被其遇到的微生物群落影響，”這篇新論文的第一作者、華盛頓大學圣路易斯醫(yī)學院(Washington University School of Medicine in St. Louis)基因科學與系統(tǒng)生物學中心(Center for Genome Science and Systems Biology)主任杰弗里·戈登(Jeffrey Gordon)博士說。健康飲食的營養(yǎng)成分必須“從內(nèi)而外”考量，他說，“而不只是由外而內(nèi)”。

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.

這項研究著手回答的問題之一是，飲食不同的個人在試圖改善自己飲食習慣時，分別會有什么樣反應(yīng)。科學家們從人體內(nèi)提取腸道細菌，將它們移植到在無菌環(huán)境下養(yǎng)殖的小鼠體內(nèi)，然后給小鼠提供美式飲食或植物為主的飲食。之后，科學家們再對小鼠體內(nèi)微生物群落的變化進行分析。

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.

值得關(guān)注的是，科學家們是從飲食習慣極為不同的兩組人群里提取腸道細菌。其中一組是典型的美國日常飲食，每天攝入約含3000卡路里的食物，有大量動物蛋白，水果和蔬菜非常少。他們最喜歡的食物包括經(jīng)過加工的奶酪、帕帕羅尼腸和午餐肉。

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.

另一組由熱衷于控制熱量攝入的人組成。他們每天吃的食物熱量少于1800卡路里，在過去至少兩年內(nèi)一直細致地監(jiān)測自己的飲食，嚴格堅持大體以植物為主的飲食。與另一組相比，他們攝入的動物蛋白要少得多，攝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.

研究人員發(fā)現(xiàn)，相比于遵循典型美國飲食的組，限制熱量攝入組的腸道微生物群落數(shù)量要多得多，種類也多得多。他們還攜帶好幾種被認為能增進健康的“有益”菌，那是他們以植物為主的飲食所特有的。“他們在成人階段的選擇，極大地改變了自己的腸道菌群，”這篇論文的主要作者、華盛頓大學的尼古拉斯·W·格里芬(Nicholas W. Griffin)說。

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.

與這項研究沒有關(guān)聯(lián)的斯坦福大學(Stanford)醫(yī)學、微生物學和免疫學教授大衛(wèi)·A·瑞爾曼(David A. Relman)表示，發(fā)表在《細胞宿主與微生物》(Cell Host & Microbe)雜志上的這項研究，不是第一篇提出轉(zhuǎn)變飲食習慣能給腸道菌群帶來持續(xù)改變的論文。他指出，其他一些研究甚至發(fā)現(xiàn)了更深刻的影響。

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實驗鼠體內(nèi)后，這些鼠要么吃類似典型美國飲食的食物，要么是類似限制熱量攝入人群的飲食。

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.

由典型美國飲食喂養(yǎng)的鼠，其腸道菌群對植物為主的飲食反應(yīng)更弱。它們的微生物群落的數(shù)量和種類沒有同等程度的增長。“它們都是朝著可預見的方向反應(yīng)，但程度沒有另一組那么大，”格里芬說。

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，這項研究也顯示，你的同伴也會豐富你的腸道菌群——至少在小鼠中是如此。一開始，這些小鼠被關(guān)在單獨的籠子里。然后，當它們被養(yǎng)在一起時，由植物類飲食產(chǎn)生的菌群便進入了由美式飲食塑造的菌群內(nèi)。

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.

目前還不清楚在人體中會有怎樣的表現(xiàn)：小鼠養(yǎng)在一起的時候會吃彼此的糞便，所以很容易交換菌群。不過，格里芬表示，人類有可能通過其他方式交換菌群。“根據(jù)之前的工作和研究，我們知道生活在一起的夫妻會發(fā)展出彼此類似的菌群，”他說。

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.

注冊營養(yǎng)師梅根·賈丁(Meghan Jardine)表示，培育更健康菌群的最佳方式，或許是通過吃更多水果、蔬菜、全谷物、豆類、堅果或植物種子來攝入更多纖維。梅根與這項研究沒有關(guān)聯(lián)，但她發(fā)表過一些倡導健康菌群的文章。(她還是推薦植物性飲食的負責任醫(yī)療醫(yī)師委員會[Physicians Committee for Responsible Medicine]的成員。)她極力主張人們努力做到每天攝入40至50克纖維，高于大多數(shù)飲食指南建議的水平。

“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.

“你觀察一下吃真正的食物，也就是堅持高纖維、更多以植物為主飲食的人群，就會發(fā)現(xiàn)他們腸道內(nèi)的菌群更有活力，有更強的遺傳多樣性，種類更健康，致病菌更少，”她說。