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减肥必备知识:肠道细菌会让你长胖吗?

更新时间:2019/3/2 10:39:33 来源:纽约时报中文网 作者:佚名

Could gut bacteria microbes make you fat?
减肥必备知识:肠道细菌会让你长胖吗?

Our guts contain around 100 trillion microbes, collectively known as the gut microbiota. No two people’s microbiomes look exactly the same, and they are a product of what we inherit from our mothers during birth, our diets, environment and lifestyle.

我们的肠道含有大约100万亿个微生物,统称为肠道菌群。没有两个人的微生物群是完全相同的,它们和我们出生时从母亲那里的遗传,以及我们的饮食、环境和生活方式有关。

It is well established that the gut plays a role in numerous systems in our body, including digestion, hunger and satiety, through multiple mechanisms, but now researchers are starting to uncover the specific differences between the microbiomes of obese and lean people, and develop personalised weight-management treatments based on their findings.

已经确定的是,肠道在我们的身体的许多系统中通过多重机制发挥作用,包括消化系统,控制饥饿和饱腹的感受系统。但现在,研究人员已经开始发现肥胖和苗条的人的微生物群落之间的具体差异,并根据他们的研究成果开发个性化的减肥疗法。

There are hundreds of differences in the human genome that predispose us to obesity, which increases the risk of developing cardiovascular diseases and type 2 diabetes, and is increasing in most countries around the world.

人类基因组中有几百种的差异使我们容易发胖,肥胖会增加罹患心血管疾病和二型糖尿病的风险,而且肥胖人群在世界上大多数国家都在持续增加。

Studies involving twins have shown that obesity has a heritability rate – how much variation in traits is caused by variation in genes, rather than the environment – of between 40% and 75%, which means there is room for external factors to play a role. But while there are many differences in gut bacteria that could influence weight, scientists don’t yet know why, or even how much of it comes down to our genes.

对双胞胎的研究表明,肥胖是有遗传比率的,约在40%到75%之间。遗传率的高低和基因变化有关,而与环境无关,这意味着有外部因素有发挥作用的空间。但是,尽管肠道细菌中有很多差异会影响体重,科学家们还不知道其中的原因,甚至不知道其中有多少是由我们的基因决定的。

Some dieters struggle more than others to lose weight, despite following sensible advice, and this may come down to the bacteria in our guts. Specifically, the enzymes carried within it.

一些节食者尽管遵循了明智的建议,还是为减不了肥而困扰。无法减肥可能取决于我们肠道中的细菌。具体地说,是其中携带的酶。

“What we eat is available to us, and to the bacteria inside our guts, which digest parts of food we lack the enzymes to do,” says Purna Kashyap, associate professor at the Mayo Clinic and head of its Gut Microbiome Laboratory.

梅奥诊所(Mayo Clinic)副教授、该诊所肠道微生物群实验室(Gut Microbiome Laboratory)负责人卡什亚普(Purna Kashyap)说,“我们吃下肚的东西能被我们身体吸收,也能被我们肠道内的细菌所吸收,这些细菌可以消化掉我们因缺少酶而无法消化的部分食物。”

“This process generates additional calories that the gut microbiota can give back to us, so it’s a mutually beneficial relationship where bacteria give us more bang for our buck from what we eat,” he says.

他说,“这个过程会产生额外的卡路里,肠道微生物群会将这些卡路里返还给我们,所以这是一种互惠互利的关系,细菌会从我们所吃的食物中给我们带来更多的能量。”

Kashyap tested to see if, when switching to a lower-calorie diet, gut bacteria can be more efficient in deriving calories from food, which would be helpful when food isn’t plentiful, but could also hinder weight loss.

卡什亚普进行了一项测试,看看换成低热量饮食时,肠道细菌是否能更有效地从食物中获取热量,这在食物不足的情况下会有助于人体吸收营养,但也可能阻碍减肥。

In a pilot study, 26 participants went on a lower-calorie diet high in fruit and vegetables, and some didn’t lose as much weight as others. Analysis of their gut bacteria found participants had different levels of two particular types of bacteria, and one, Dialister, that hindered weight loss.

在一项测试研究中,26名参与者均采用水果和蔬菜为主的低热量饮食,但其中一些人的减肥效果没有其他人好。对他们肠道细菌的分析发现,参与者体内两种特殊细菌的水平不同,其中一种是小杆菌属(Dialister),是这种细菌阻碍了减肥。

In those unable to lose weight, this bacteria was able to break down carbohydrates and use their energy. more effectively, Kashyap says.

卡什亚普说,这种细菌在那些无法减肥的人体内能分解碳水化合物,更有效地利用食物的能量。

However, Kashyap says that only a fraction of weight loss can be controlled by these microbes.

然而,卡什亚普说,这些微生物只能控制减肥的一小部分。

“It makes biological sense that the bacteria may be hindrance, but they can only play a small role as they produce only a small number of calories needed.”

“从生物学上讲,这种细菌可能会阻碍减肥,但它们只能发挥很小的作用,因为它们只产生少量所需的卡路里。”

While the research couldn’t conclude where Dialister comes from, one study found that some bacteria we get from our diet could indirectly cause weight gain by changing the gut’s behaviour.

虽然这项研究不能找出小杆菌属的来源,但一项研究发现,我们从饮食中获得的一些细菌可以通过改变肠道的行为间接导致体重增加。

Researchers analysed the blood plasma and stool samples of 600 obese and non-obese people, and found 19 different metabolites linked to four types of gut bacteria that could lead to weight gain, including glutamate, linked to obesity, and BCAAs (branched chain amino acids), associated with higher insulin secretion and risk of type 2 diabetes and cardiovascular disease.

研究人员分析了600名肥胖和非肥胖者的血浆和粪便样本,发现了与四种可能导致体重增加的肠道细菌有关的19种不同的代谢物。这些代谢物包括谷氨酸(glutamate)和支链氨基酸(BCAAs,branched chain amino acids)。前者与人肥胖有关,而后者可导致胰岛素分泌较高及患上二型糖尿病和心血管疾病的风险升高。

These metabolites may be partly determined by meat consumption, according to researcher Louise Brunkwall.

据研究员布伦克沃尔(Louise Brunkwall)称,这些代谢物可能部分是由肉类摄入决定的。

“The metabolite pattern that we identified contained a lot of branched chain amino acids, which are found in animal products. This is in line with other research that show that a high protein intake increases the risk for several diseases.”

“我们发现的代谢物模式中含有大量的支链氨基酸,动物制品中可以找到这些成分。其他研究表明,摄入大量蛋白质会增加罹患多种疾病的风险,我们的发现与这些研究一致。”

Brunkall says research needs to focus on how the composition of gut bacteria can be modified to reduce the risk of obesity, as well as understand what a healthy gut looks like, and what factors change its bacterial composition.

布伦克沃尔说,研究需要关注如何改变肠道细菌的组成来降低肥胖的风险,还要了解一个健康的肠道是什么样子,以及是什么因素改变了它的细菌组成。

There is no clear picture yet of the differences in the gut bacteria profile of lean versus obese people, says Oluf Pedersen, professor of Metabolic Genetics at the Novo Nordisk Foundation Center for Basic Metabolic Research at the University of Copenhagen. But what is being established is the importance of having a diverse intestinal microbiota, filled with many different types of bacteria.

哥本哈根大学(University of Copenhagen)诺和诺德斯克基础代谢研究基金中心(Novo Nordisk Foundation Center for Basic metabolism Research)的代谢遗传学教授彼得森(Oluf Pedersen)说,目前还不清楚瘦的人和肥胖的人肠道细菌分布的差异。但目前学术界正在确定的是,拥有一个充满多种不同细菌的多样肠道菌群对人体非常重要。

Pedersen and his team analysed the gut bacteria of 123 non-obese and 169 obese adults, and found that the 23% of those who had a comparatively low diversity were more likely to be obese, have insulin resistance and elevated blood lipids, and increased levels of inflammation markers in the blood, all of which increase the risk of type 2 diabetes and cardiovascular disease. Those who were both obese and had lower bacterial diversity gained much more weight over the previous nine years.

彼得森和他的团队分析了123名非肥胖者和169名肥胖成年人的肠道细菌,发现那些肠道细菌种类多样性相对较低的人中有23%更容易发胖,他们有胰岛素抵抗且血脂升高现象,其血液中的炎症标志物水平也有上升,所有这些症状都提高了患二型糖尿病和心血管疾病的风险。在过去的九年里,那些肥胖且细菌多样性较低的人所增加的体重也较多。

Pedersen says the reasons some people have more gut bacteria diversity than others isn’t yet understood, but scientists do know that having multiple antibiotic treatments can contribute to a major loss of bacteria that never fully recovers.

彼得森说,为什么一些人体内的肠道细菌种类会比另外一些他人多,其原因尚不清楚,但科学家知道,使用多种抗生素治疗会导致人体肠道细菌大量流失,而这些细菌一旦消失则永远无法完全恢复。

It isn’t fully established whether diversity of bacteria is a cause or consequence of weight gain, however, there is evidence that the microbiome can influence metabolism.

肠道细菌种类的多寡是体重增加的原因还是结果,这还不能完全确定,但是有证据表明微生物群可以影响新陈代谢。

One study found that we may be able to achieve higher gut microbiota diversity by increasing our fibre intake. When we consume fibre, our guts break it down into short chain fatty acids, including butyrate, an anti-inflammatory linked to leanness and lower inflammatory diseases, explains Ana Valdes, author of the study and associate professor at the University of Nottingham.

一项研究发现,我们可以通过增加纤维摄入量来获得更高的肠道菌群多样性。这项研究的作者、诺丁汉大学(University of Nottingham)副教授瓦尔德斯(Ana Valdes)解释说,当我们摄入纤维时,我们的肠道会将其分解成短链脂肪酸,其中包括丁酸盐(butyrate),这种抗炎物质与消瘦和炎症疾病较少有关。

“If people with type 2 diabetes go on a high-fibre diet, you can reduce their diabetes status and increase butyrate production,” she says.

她说,“如果二型糖尿病患者采用高纤维饮食,他们的糖尿病水平会下降,丁酸盐的产生会增加。”

“People who have more diverse microbiomes and eat more fibre have less insulinogenic diets (consisting of foods that give us lower spikes in glucose and insulin), and probably have higher energy expenditure.”

“微生物群较多样化、纤维摄入较多的人,胰岛素原性饮食(由葡萄糖和胰岛素峰值较低的食物构成)也较少,这可能会消耗更多的能量。”

“We need to test this properly, but gut bacteria could convert the fibre into substances that modulate insulin sensitivity and energy metabolism.”

“我们需要进行适当的测试,但肠道细菌可以将这些纤维转化为调节胰岛素敏感性和能量代谢的物质。”

Recent, and arguably the most ground-breaking research into the link between weight and gut health so far involves the bacterial species Christensenellaceae. Around 97% of us have detectable levels of the bacteria in our guts, but it has been found to be more present in lean people.

目前为止,最近关于体重和肠道健康之间关系的研究课题中,可论证的最具突破性的成果是有关克里斯滕森菌科(Christensenellaceae)这种细菌种类的研究。我们当中97%的人的肠道中都检测到这种细菌,但研究发现,在身形苗条者体内的这种细菌则较多。

When researchers looked at heritable gut microbes, Christensenellaceae came top of the list, found in gut microbiomes around the world and showing up from a very early age, including in the guts of babies.

当研究人员研究可遗传的多种肠道细菌时,克里斯滕森菌科名列榜首,因为它存在于世界各地人体的肠道微生物群中,而且在人一出生的时候就出现,包括婴儿的肠道中也有。

“We’d never heard of it before, and we pride ourselves on knowing names of things,” says Ruth Ley, lead researcher on the study and director of the Department of Microbiome Science at the Max Planck Institute for Developmental Biology.

这项研究的首席研究员、麦克斯·普朗克发展生物学研究所(Max Planck Institute for Developmental Biology)微生物组科学部(Department of Microbiome Science)主任利(Ruth Ley)说,“我们以前从未听说过这种肠道菌,我们很自豪,竟然能找到了这种细菌的名字。”

“We had to go back and look at where it had been this whole time, but it had only just been named so it wasn’t searchable by name, only by sequence,” she says.

她说,“我们必须从头开始,去研究此菌的历史。因为才刚刚命名,所以我们不是按名字,而是按基因测序才查到这种细菌。”

Researchers transplanted an obese-associated microbiome, amended to include Christensenellaceae, into mice and found that it protected them against weight gain.

研究人员将一种与肥胖相关而且修改过的微生物群移植到老鼠体内,特地将克里斯滕森菌科也增加进去,结果发现,这组微生物群可以防止老鼠体重增加。

“Since host genetics only account for around 40% of relative abundance, we don’t know where 60% of Christensenellaceae is coming from,” says Jillian Waters, who was part of the research team who discovered the bacteria’s ability to protect rats from gaining weight. She has a hunch it comes from our diet and lifestyle, and now, researchers are trying to get to the bottom of what it actually does and where it comes from, to pave the way for future treatment.

“由于宿主基因只占相对含量的40%左右,我们不知道60%的克里斯滕森菌科来自哪里,”沃特斯(Jillian Waters)说。她是研究小组的一员,该小组发现了这种细菌可以防止老鼠体重增加。她有一种预感,认为这种肠道菌来自我们的饮食和生活方式,现在,研究人员正试图弄清其实际作用和来源,为未来的治疗铺平道路。

In the meantime, researchers from the Weizmann Institute in Israel have found a way personalise treatment to benefit gut health and lower the risk of developing diabetes, which is associated with obesity.

与此同时,以色列(Israel)魏茨曼研究所(Weizmann Institute)的研究人员发现了一种个性化治疗的方法,既有利于肠道健康,又能降低与肥胖有关的糖尿病的风险。

Researchers recruited 1,000 participants, and tasked them with measuring their blood sugar every five minutes and recording their diets, how they slept and felt for one week, and found that they reacted differently to different foods.

研究人员招募了1000名参与者,要求他们每5分钟测量一次血糖,记录他们一周的饮食、睡眠和感觉,结果发现他们对不同食物的反应不尽相同。

“Many foods created the reactions we’d expect in people, for example, eating meals without any sugar kept blood sugar constant in most people, and sugary foods made levels spike, but the degree to which this happens varies greatly between people,” says Eran Segal, lead scientist on the project.

该项目的首席科学家西格尔(Eran Segal)说,“许多食物会产生我们所预期的人体反应,例如,不含糖的食物会使大多数人的血糖保持稳定,而含糖食物会使血糖水平飙升,但食物反应的程度对于不同的人差别甚大。”

“Tomatoes are one food that spikes levels quite a lot for some people, so the amount they eat should be controlled, while others may find a single food is bad for them but, when combined with another food, might be better.”

“西红柿会使某些人血糖飙升,所以他们应该控制自己的摄入量,而另一些人可能会发现某种单一的食物对他们有害,但与另一种食物结合起来可能会更好。”

From the data they collected, the researchers developed a computer algorithm that could take a person’s gut bacteria composition and predict how their blood sugar levels will react to different foods. They tasked 25 participants with eating food deemed ‘good’ for their blood sugar for one week, then food deemed ‘bad’. The diets changed their blood sugar reactions and successfully balanced blood sugar levels.

根据收集到的数据,研究人员开发了一种电脑算法,可以提取出一个人肠道细菌的组成,并预测他们的血糖水平对不同食物的反应。他们让25名参与者一周吃被认为对血糖有益的食物,然后让他们一周吃被认为对血糖有害的食物。这些饮食改变了他们的血糖反应,成功地平衡了血糖水平。

Our gut bacteria and individual blood sugar responses to different foods may evolve over time, Segal says, but this would take a long time, and our guts before and after changes would still be more similar than how our guts compare to another person.

西格尔说,我们的肠道细菌和个人血糖对不同食物的反应可能会随着时间的推移而变化,但这需要很长时间,而且我们的肠道变化前后的差异往往要小于我们和他人肠道的差异。

The algorithm has been licensed to start-up Day Two, which offer services in Israel and US, and is planning to expand to the UK in the near future. Segal is now conducting research on people with pre-diabetes and diabetes and is seeing that personalised diets designed through the algorithm, when maintained for a longer period, can reverse both pre-diabetes and diabetes.

初创公司“Day Two”已获准使用该算法在以色列和美国开展服务,并计划在不久的将来扩展到英国。西格尔目前对患糖尿病前趋症和糖尿病的患者正在进行研究,发现通过该算法设计的个性化饮食,如果维持较长时间,可以逆转糖尿病前趋症和糖尿病。

Researchers are hopeful that other personalised treatments will be available in the next five years – but there is a lot of work to do yet.

研究人员希望在未来五年内能有其他个性化的治疗方法,但实现此目标之前还有很多工作要做。

The bacteria in our guts, says Kashyap, are capable of complex biochemical reactions.

卡什亚普说,我们肠道中的细菌能够进行复杂的生化反应。

“We now need to understand how these bacteria influence each of these processes, leading to obesity and diabetes, which are complex, multifactorial diseases.

“肥胖和糖尿病都是复杂的多种因素造成的疾病,我们现在需要了解这些细菌导致这两种疾病的每一个过程。”

“The microbiome is changeable, we can modify it. If we can figure out how gut bacteria is driving it, we should be able to target it at multiple levels, which will each have an impact on treatment of obesity. There’s no doubt the microbiome is a part of that solution.”

“微生物群是可变的,我们可以改变它。如果我们能弄清楚肠道细菌是如何操纵它的,我们应该能够在多个层面上针对它,这将对肥胖的治疗产生影响。毫无疑问,微生物群是解决方案的一部分。”

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