Jefferson Angie, Adolphus Katie
Independent Researcher, Bracknell, United Kingdom.
The Kellogg Company, Manchester, United Kingdom.
Front Nutr. 2019 Mar 29;6:33. doi: 10.3389/fnut.2019.00033. eCollection 2019.
The human microbiota is increasingly recognized as a major factor influencing health and well-being, with potential benefits as diverse as improved immunity, reduced risk of obesity, Type 2 diabetes, and improved cognition and mood. Bacteria inhabiting the gut are dependent on the provision of fermentable dietary substrates making diet a major factor driving the composition of the human gut microbiota. Dietary fiber may modify microbiota abundance, diversity, and metabolism including short-chain fatty acid production. The majority of research to date has explored isolated fibers, and the influence of habitual fiber consumption is less well-established. The aim of the current article was to systematically review evidence from human intervention studies for the effects of intact cereal fibers, and their active sub-fractions, on gut microbiota composition in healthy adults. Studies published in the past 20 years were identified through the PubMed and Cochrane electronic databases. Inclusion criteria were: healthy adult participants (>18 years), inclusion of at least one intact cereal fiber, or its sub-fraction, and measurement of fecal microbiota related outcomes. As every individual has a unique microbiota many trials utilized a cross-over design where individuals acted as their own control. Outcome measures included change to the microbiota, species diversity, or species abundance, or metabolic indicators of microbiota fermentation such as short chain fatty acids or fecal nitrogen. Two hundred and twenty three publications were identified and 40 included in the final review. In discussing the findings, particular attention has been paid to the effects of wheat fiber, bran, and arabinoxylans (AXOS) as this is the dominant source of fiber in many Western countries. Thirty-nine of the forty-two studies demonstrated an increase in microbiota diversity and/or abundance following intact cereal fiber consumption, with effects apparent from 24 h to 52 weeks. Increases in wheat fiber as low as 6-8 g were sufficient to generate significant effects. Study duration ranged from 1 day to 12 weeks, with a single study over 1 year, and exploration of the stability of the microbiota following long-term dietary change is required. Increasing cereal fiber consumption should be encouraged for overall good health and for gut microbiota diversity.
人类微生物群越来越被认为是影响健康和幸福的主要因素，具有多种潜在益处，如增强免疫力、降低肥胖、2型糖尿病风险，以及改善认知和情绪。栖息在肠道中的细菌依赖于可发酵膳食底物的供应，这使得饮食成为驱动人类肠道微生物群组成的主要因素。膳食纤维可能会改变微生物群的丰度、多样性和代谢，包括短链脂肪酸的产生。迄今为止，大多数研究都探索了分离出的纤维，而习惯性纤维摄入的影响尚不明确。本文的目的是系统回顾来自人体干预研究的证据，以了解完整谷物纤维及其活性亚组分对健康成年人肠道微生物群组成的影响。通过PubMed和Cochrane电子数据库检索了过去20年发表的研究。纳入标准为：健康成年参与者（>18岁），纳入至少一种完整谷物纤维或其亚组分，并测量粪便微生物群相关结果。由于每个人都有独特的微生物群，许多试验采用交叉设计，个体作为自己的对照。结果指标包括微生物群的变化、物种多样性或物种丰度，或微生物群发酵的代谢指标，如短链脂肪酸或粪便氮。共识别出223篇出版物，最终纳入综述的有40篇。在讨论研究结果时，特别关注了小麦纤维、麸皮和阿拉伯木聚糖（AXOS）的影响，因为这是许多西方国家纤维的主要来源。42项研究中的39项表明，食用完整谷物纤维后微生物群多样性和/或丰度增加，从24小时到52周都有明显效果。低至6-8克的小麦纤维增加量就足以产生显著效果。研究持续时间从1天到12周不等，只有一项研究超过1年，因此需要探索长期饮食变化后微生物群的稳定性。为了整体健康和肠道微生物群多样性，应鼓励增加谷物纤维的摄入量。
