益生菌酸奶有益肠道健康？研究发现：没有多大作用

★专业/深度/睿见资讯尽在医疗旅游

益生菌无论是放入酸奶中，还是装在胶囊中在药房出售，在注重健康的人们中都很流行，全世界数百万人都在使用益生菌！

但美国胃肠病学协会（AGA）的一份新报告说：这些所谓的好细菌对肠道健康没有多大作用，包括克罗恩病，溃疡性结肠炎或肠易激综合症等消化系统疾病。

“对于我们研究的大多数消化系统疾病，目前没有足够的证据推荐使用益生菌，”德克萨斯医学中心儿科胃肠病学家，AGA发言人Geoffrey Preidis博士说。

不同的地方，益生菌可以通过柜台或处方出售-但这些补充剂可能价格昂贵，而且配方差异很大。

密歇根大学安医学教授兼胃肠科主任格雷斯·L·苏博士（Dr.Grace L.Su）在声明中说：“虽然我们的指南确实强调了益生菌的一些使用案例，但更重要的是，它强调了公众对益生菌益处的假设是没有充分根据的”。她是发布新指导意见的小组主席。

细菌和酵母

益生菌是微小的活生物体，包括某些细菌和酵母菌，通常存在于酸奶或膳食补充剂等食物中。

根据世界卫生组织的说法，“益生菌是活的微生物，当以足够的剂量给药时，会对宿主产生健康益处。”

华盛顿大学药物化学副教授Lynne McFarland表示，对现有研究和研究回顾的一个优势在于，它独立地考虑了益生菌的每一个单一菌株或多菌株配方的影响，而不是将它们归为一组。

McFarland说：“选择有效的益生菌意味着将特定的益生菌菌株与需要治疗的疾病类型相匹配。在大多数情况下，益生菌产品上的标签是没有帮助的。”

随着研究人员对肠道细菌或微生物群对胃肠道健康的作用了解得更多，益生菌已变得越来越流行，益生菌有望成为改变微生物群的一种有效途径，从而使我们受益。

Su博士说：“我们希望，随着我们对微生物群有了更好了解，我们将能够更有效地选择在某些情况下可能有益的益生菌。”

但是，由于益生菌在美国或欧洲不被认为是药物，因此它们没有像药品那样受到监管，Preidis 博士说，这让消费者得到误导性的信息，并成为科学研究益生菌如何帮助治疗疾病的障碍。

新准则说：“该行业基本上不受监管，产品营销通常直接针对消费者，而没有提供直接和一致的有效性证明。” “这导致了益生菌的广泛使用，混淆了临床疗效的证据”。

该报告估计，有390万美国成年人使用了某种形式的益生菌或益生元（促进微生物生长或有益微生物功能的营养素），是的四倍。该行业正在蓬勃发展，预计今年在美国的销售额将超过60亿美元。

患者通常会询问临床医生是否应该服用益生菌，如果是，应该服用哪些产品。这些问题提出了一个两难的境地，因为目前正在研究的益生菌制剂都不是作为药物生产的，其目的是减轻或预防疾病。

Preidis博士说，益生菌可能在某些情况下造成伤害，特别是在免疫系统受损的人中。他敦促任何想开始益生菌治疗的人与他们的医生交谈。

他说：“最严重的副作用是感染。作为活的微生物，益生菌可以离开肠道进入血液，引起败血症。”

McFarland也说，不应将益生菌视为一种健康时尚。

她说：“并不是所有的益生菌都是一样的。一些益生菌菌株和混合物对某些类型的疾病非常有效，不应被忽视，因为研究将所有益生菌作为一个整体。”

益生菌可以在哪里提供帮助

研究确实发现益生菌在某些情况下有帮助。

特定的益生菌可以帮助出生时体重低的早产儿减少全量喂养所需的天数，并缩短住院时间。

同样，应考虑使用某些益生菌来预防服用抗生素C的成人和儿童引起的的艰难大肠杆菌感染。大肠杆菌是引起腹泻和结肠发炎的细菌。

该研究还发现，益生菌可以考虑用于治疗囊袋炎，这是通过手术治疗的溃疡性结肠炎的并发症。

但是，该研究发现，关于使用益生菌治疗艰难大肠杆菌感染，克罗恩病，溃疡性结肠炎或IBS的证据不足。实际上，AGA建议患有这些疾病的人考虑停止服用益生菌，因为“相关的费用不低以及没有足够的证据表明没有危害”。

该研究还得出结论，益生菌对北美患有急性胃肠炎的儿童没有益处，并建议对腹泻儿童不应常规使用益生菌。

但是，McFarland说，这项审查没有考虑到美国以外的研究，这些研究表明，某些益生菌可以有效缩短儿童急性腹泻的持续时间，特别是在发展中国家。＊

Probiotics don do much for most peoples gut health despite the hype, review finds

Whether contained in yogurt or stuffed into capsules and sold on pharmacy shelves, probiotics are popular among the health conscious, with millions of people around the world thought to use them.

But a new report from the American Gastroenterological Association said that these so-called good bacteria don do much for gut health — including digestive conditions like Crohns disease, ulcerative colitis or irritable bowel syndrome.

"For the majority of the digestive diseases we studied, currently there is not enough evidence to recommend using probiotics," said Dr. Geoffrey Preidis, a pediatric gastroenterologist at the Texas Medical Center and spokesperson for the AGA.

Depending on where you live, probiotics are sold over the counter or by prescription -- but the supplements can be costly and their formulation varies widely.

"While our guideline does highlight a few use cases for probiotics, it more importantly underscores that the publics assumptions about the benefits of probiotics are not well-founded," said Dr. Grace L. Su, a professor of medicine and chief of gastroenterology at the University of Michigan, Ann Arbor, in a news statement. She was the chair of the panel that issued the new guidance.

Bacteria and yeasts

Probiotics are tiny living organisms, including certain bacteria and yeasts, that are usually found in foods like yogurt or dietary supplements.

"Probiotics are live microorganisms which when administered in an adequate dose confer a health benefit on the host," according to the World Health Organization.

One strength of the reviewof existing research and studieswas that it considered the effect of each single-strain or multi-strain formulation of probiotics independently, instead of lumping them together as one group, said Lynne McFarland, an associate professor of medicinal chemistry at the University of Washington.

"Selecting an effective probiotic means matching the specific probiotic strain to the type of disease that needs treatment. Most of the time, the labels on the probiotic products are not helpful," said McFarland, who was not involved in the review.

Probiotics have become more popular as researchers have learned more about the role of our gut bacteria, or microbiome, on our gastrointestinal health, with probiotics promising an effective way of altering the microbiome for our benefit.

"Our hope would be that as we understand the microbiome better, we will be able to more effectively select the probiotics that may be beneficial in certain circumstances," said Dr Su.

However, because probiotics aren considered drugs in the United States or Europe, they aren regulated like a pharmaceutical product, which Dr. Preidis said allowed consumers to be given misleading information and acted as a barrier to scientific research on how probiotics may help treat a disease.

"The industry is largely unregulated and marketing of product is often geared directly at consumers without providing direct and consistent proof of effectiveness," said the new guidelines. "This has led to widespread use of probiotics with confusing evidence for clinical efficacy," it said.

The report estimated that 3.9 million American adults used some form of probiotics or prebiotics (nutrients which promote growth or beneficial functions of microbes) in , four times more than in . The industry is booming, with sales in the United States expected to exceed $6 billion this year, according to the report.

"Patients routinely ask clinicians whether they should be taking probiotics — and if so, which products. These questions present a dilemma, given that none of the probiotic preparations being studied are currently manufactured as drugs — with the intent of treating, mitigating or preventing disease," said the technical review that accompanied the new guidelines.

Probiotics can cause harm in some circumstances, particularly in people with compromised immune systems, said Dr. Preidis, who urged anyone thinking of starting a probiotic regimen to speak to their doctor.

"Among the more serious side effects is infection. As living microbes, probiotics can leave the intestines and enter the bloodstream, causing sepsis," he said

McFarland, however, said that probiotics shouldn be dismissed as a health fad.

"Not all probiotics are created equal. Some probiotic strains and mixtures are very effective for some types of diseases and should not be overlooked due to studies that lump all probiotics together as one," she said.

Where probiotics can help

The review did find that probiotics can help in certain circumstances.

Specific probiotics can help pre-term babies born with a low birthweight reduce the number of days they need to take full feedsand shorten the time they spent in hospital.

Likewise, certain probiotics should be considered for the prevention of Clostridium difficile infections in adults and children who take antibiotics. C. difficile is a bacteria that cases diarrhea and inflammation of the colon.

The review also found that probiotics could be considered for the management of pouchitis, a complication of ulcerative colitis that has been treated surgically.

However, the review found there wasn enough evidence regarding the use of probiotics to treat C. difficile infection, Crohns disease, ulcerative colitis or IBS. In fact, the AGA suggested people with these conditions consider stopping probiotics because of "the associated costs and not enough evidence to suggest lack of harm."

It also concluded that probiotics weren beneficial for children in North America who have acute gastroenteritis and advised that they should not be given routinely in ER to children with diarrhea.

However, McFarland said the review had not taken in account research done outside the US, which had shown that certainprobiotics were effective in shortening the duration of acute diarrhea in children, particularly in developing countries.