高纖、低脂的飲食讓 你養出好的腸道細菌

高纖、低脂的飲食讓 你養出好的腸道細菌

 

我們並不孤單！除了自身的細胞構築出來的肉體，這軀體上其實還住有各式各樣的客人，皮膚上、口腔裡，在消化系統裡面也有，它們是一群名為腸道細菌的寄宿者，先前的研究讓我們漸漸知道它們跟人體的健康有關，而新研究發現它們還可能會幫我們減個幾斤幾兩的體重。

研究由一群跨國科學家所組成的團隊主導，他們發現一個富含纖維的飲食會改變腸道菌叢的組成，而這樣的變化或許能幫助人們減少一些體重。雖然這些年來我們大多有腸道細菌會影響人們的健康與肥胖，只是箇中確切的原因科學家們還不是很清楚。

研究發現體重最重的人們腸內會缺乏某系列的細菌或是族群量很少。從這點來看，未來我們或許能以此發展出對抗肥胖的細菌療法。

專家們認為腸道是體重增加或是減少的關鍵。目前腸道細菌對整體健康是有益的概念已經廣為人知，而它們的重要性可能跟我們自身的免疫反應以及適當的營養一樣。也就是說，如果因為濫用抗生素或是吃只利某種細菌生長的飲食而打亂了腸道菌叢的構成的話，就可能會因此而影響身體的健康。

首先，一篇去年三月發表在 Science Translational Medicine 期刊上的研究對老鼠進行胃繞道手術，結果使牠們體重下降，而這個手術改變了牠們腸內的細菌組成。一般我們認為胃繞道手術能減重的原因是減少胃容積而讓人少吃，然而這個研究則帶來另外一個可能的原因——腸道細菌改變了。

體重越重，腸內細菌分佈越單調

新研究發表在 2013.8.29 的 Nature 期刊上，第一個研究分析 169 位肥胖與 123 位體重正常的丹麥人腸道內的細菌。

與體重正常的人相比，肥胖者的腸道細菌比較不多樣化，而在代謝上也有異常的情形。此外，細菌分布越是單調的肥胖者，體重增加得越多。科學家目前還不清楚為何細菌的組成與肥胖有關。不過研究者們認為細菌本身的代謝會與宿主的代謝連結。

高纖低脂飲食有助腸內細菌多樣化

第二個研究以 49 位體重過重或肥胖的人為對象，他們試著以飲食控制的方式減重，在這期間研究者們會觀察他們腸道菌像的變化。他們的飲食設計是低脂、低熱量並含豐富的蛋白質與纖維的飲食，纖維主要來自蔬菜與水果等食物。結果發現這樣的飲食確實能改變這群人們的腸道細菌的組成。

儘管現在針對這個主題的研究數量與規模都相對較小，但它們確實告訴我們一種可能性：藉由飲食的管理能改善腸道菌叢的豐富度，並降低變胖。不過這不代表結果對每個人都能發揮作用，或是以為只要腸道菌相豐富就不會胖，而卯起來吃。

Studies also found that high-fiber, low-fat diet can change bacteria makeup for the better

WebMD News from HealthDay

By Randy Dotinga

HealthDay Reporter

WEDNESDAY, Aug. 28 (HealthDay News) -- Bacteria in people's digestive systems -- gut germs -- seem to affect whether they become overweight or obese, and new research sheds more light on why that might be.

The findings, from an international team of scientists, also suggest that a diet heavy in fiber could change the makeup of these germs, possibly making it easier for people to shed pounds.

"We know gut bacteria affect health and obesity, but we don't know exactly how," said Dusko Ehrlich, a co-author of the two new studies and coordinator of the International Human Microbiome Standards project.

The research finds that "people who put on the most weight lack certain bacterial species or have them at very low levels. This opens ways to develop bacterial therapies to fight weight gain," he said.

Experts believe the gut, where the body processes food, is crucial to weight gain and weight loss.

"It is now well known that bacteria in our gut play an important role in our health and well-being, possibly as important as our own immune response and proper nutrition," said Jeffrey Cirillo, a professor at Texas A&M Health Science Center's department of microbial pathogenesis and immunology. "This means that disruption of the bacteria in our gut by use of antibiotics or eating foods that help only particular bacteria grow can have effects upon our entire bodies."

A study released last March in the journal Science Translational Medicine suggested that gastric bypass surgery led to weight loss -- in mice -- because it changed the makeup of the bacteria in their intestines.

In one of the new studies, which are both published in the Aug. 29 issue of the journal Nature, researchers analyzed the gut bacteria of 169 obese Danish people and 123 Danish people who were not obese.

The gut germs in the obese people were less diverse than in the others, and had more abnormalities in terms of metabolism. Also, obese people with a less diverse supply of germs gained more weight.

It's not clear how the bacteria and obesity are related. But the research suggests that the metabolisms of the germs themselves are connected to the overall metabolism in the humans where they live, Cirillo said.

The finding could also have a practical application, the researchers said.

"The study lays ground for a simple test, which should tell people what their risk for developing obesity-linked diseases is," study co-author Ehrlich said. If they are, he said, diet changes may be necessary.

In a second study, researchers monitored gut bacteria as 49 overweight and obese people tried to lose weight with diets that were low-fat and low-calorie but high in protein plus fiber-rich foods like vegetables and fruits. The diet appeared to actually change the bacterial makeup in the guts of the participants.

"Although these are relatively early and small studies on the topic, they suggest that management of our own diets can improve the richness of the flora within our guts and decrease our chances of becoming obese," said Cirillo. "This does not mean that changes in diet will be effective for all people or that they can prevent obesity no matter how much someone eats, but that they can help the situation."