When it comes to bugs like bacteria and parasites, we've been trained to think that less is better. But there are some good guys in the microbial world — bugs that do the unglamorous work of keeping us regular and helping to relieve a range of disorders from diarrhea to irritable bowel syndrome (IBS). Now, a new study suggests that the same microbes may even help us stay slim.

    In the Proceedings of the National Academy of Science, researchers at the University of Arizona and the Mayo Clinic in Arizona report a very small study of nine individuals — three of normal weight, three who were morbidly obese and three who underwent gastric bypass surgery. The team found that each group harbored a different intestinal zoo of microbes, and that following their surgery, the gastric bypass patients' gut bugs ended up looking much more similar to those of the normal weight patients.

    While these results are only preliminary, they do point to an entirely new way that doctors and patients might be able to tackle the growing obesity epidemic in the U.S. "This study suggests that the differences in the organisms may play at least some role in why people lose the weight they do," says Dr. John DiBaise, a gastroenterologist at Mayo Clinic and one of study's authors. "Ultimately, we may not only be able to manipulate the microbes of obese individuals to look like those of normal weight people, but we might also potentially be able to predict a person's susceptibility to obesity."

    What might be happening, suspects DiBaise, is that each person's ability to extract energy and store fat from food changes depending on which combination of bugs are living in the gut. Those who are morbidly obese, it seems, tend to nurture bugs that promote the fat storage process, which might be a factor in their excessive weight gain. The bypass patients appeared to follow a similar pattern but in the opposite direction, eating less first and then developing bugs appropriate to that diet. It's not clear how the physical act of reducing food intake drives that change, nor how long-lasting the possible slimming effects of the new bug population will be.

    But none of this means that downing the latest probiotic yogurts, which contain certain strains of good gut bacteria, should be the next weight loss craze. For one, says DiBaise, the strains that were dominant in the normal weight people are not the same as those promoted in the popular probiotic yogurts. Second, there is no evidence that probiotic products can do anything about weight loss; the latest scientific studies have shown only that probiotics can relieve antibiotic-related diarrhea, as well as alleviating IBS and aiding regularity. "It is interesting to look at microbial flora," says Lynne McFarland, an epidemiologist at the Puget Sound Veterans Administration Medical Center, who was not affiliated with the study. "But I would not run out and eat a lot of yogurt because of this."

    At least, not yet. More studies are needed to follow the same people as they lose weight through diet and exercise, to see if the composition of their gut flora changes — as it did with the gastric bypass patients. What's more, notwithstanding the seemingly cause-and-effect link between gut flora and weight, that relationship can be deceiving; a third factor entirely may be causing both — a diet of highly processed foods, for instance, suggests Dr. David Katz, director of the Yale Prevention Research Center. What's more, says Katz: "Regardless of the variation of gut flora in the population, the entire population is getting heavy. So probiotics might tweak one's personal vulnerability to obesity, but they would not much move the big dial [on the obesity epidemic]," he says. Still, as anyone fighting the numbers on the scale knows, every little bit helps — even something a little as a bacterium.

    當談到細菌和寄生蟲的時候，我們習慣性的都認為越少越好。 實際上在微生物界中有一些好蟲子的，它們做著枯燥無聊的工作來維持我們的身體正常運轉，還能預防從腹瀉到腸道紊亂綜合癥的病癥。 現在新的研究發現這些微生物甚至幫助我們保持苗條。

    在一項美國國家科學院亞利桑那州大學和馬奧診所的研究者們進行的小范圍試驗中，有9個被觀測者，三個正常體重，三個肥胖癥，還有三個要做胃旁路手術的病人。 研究團隊發現不同組的人體腸道中的菌群是完全不同的。在手術后，那三個有胃病的人最后的腸道菌群變的和正常體重的病人相近了。

    雖然這些結論只是初級的，但它確實為醫生和病人降低美國日益增長的肥胖癥比率打開了一扇新的大門。作為這項研究的主要研究員，馬奧診所的胃腸病學家約翰.迪拜瑟醫生說:“這項研究說明這些微生物肯定在在人們的減肥過程中扮演了什么角色。如果弄得好，我們可能不僅讓胖子們的腸道菌群和正常人的一樣，還可以預測一個人會不會變胖。”

    拜瑟醫生懷疑，每個人吸收營養、存儲脂肪的能力和自己的腸道菌群的種類組合息息相關。胖子們的似乎在腸道內飼養了一群會提高脂肪存儲的微生物才造成了他們的肥胖。而那些胃旁路患者也走了相同的路，不過方向剛好相反，吃的少，也就養成了適合節食的菌群。對于運動和減少食物攝入如何影響這種變化和這些減肥效果能減肥的新菌群能堅持多久還不是很清楚。

    但是這些結果不意味著喝含有一些良性菌的最新酸牛乳會成為下一個減肥風潮。拜瑟醫生說，首先，人體腸道中的菌群和算牛乳的菌群是不一樣的。其次，這些產品和能不能減肥基本沒啥關系。最新的研究也只是發現這些飲料可以緩解抗生素相關的腹瀉，減輕腸道綜合癥和穩定腸道。沒有參與本研究的皮熱老兵健康管理醫療中心的流行病學家林恩.馬克弗蘭說：“觀察微生物菌從是很有意思的，那我也不能因此跑出去吃一大堆酸乳酪啊！”

    至少，現在還不行。還需要做更多的試驗。觀察同一些人在節食和鍛煉后他們的腸道菌群組合變化是否和那些胃旁路手術的病人的一樣。 還有，盡管腸道菌群和減肥之間看似有因果關系，但這種關系也許具有欺騙性。耶魯預防研究中心的大衛.卡茨說，可能有第三種因素同時導致了前二者，比如一份對都是高殺菌處理食物的食譜。他還說，“無視人們腸道菌群的種類變化，人們還是在變重，就算它們能減弱人對肥胖趨勢，還是改變不了大趨勢。”但那些和秤上表針戰斗的胖子們還是要抓緊最后的稻草-哪怕這稻草只有細菌那么小。