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肠脑轴

你可能听说过内脏-大脑轴,但它是什么意思呢?

众所周知,极端的情绪或压力会引起肠道紊乱. 表达式的撕心裂肺的痛苦, “担心生病”和“胃里的蝴蝶”是常见的说法. The connection between our gut and our feelings is widely accepted but it might also influence our cognition as well. 肠道被称为“第二大脑”,但这是怎么回事呢?

不可思议的肠道

肠是一个复杂的感觉器官有着巨大的表面积, 就像皮肤, 面对外部环境. 它有很多方法来检测肠道内容物:神经元, 内分泌细胞和免疫细胞, 这些检测系统比身体其他任何器官都要广泛. The enteric nervous, an enteric division of the autonomic nervous system, contains 108 神经元. 肠道内分泌系统使用20多种已确认的激素, 肠道中有70-80%的人体免疫细胞. All these enable absorption of nutrients but also protect against intrusion of harmful toxins and bacteria that may come along with food. (Furness 1999)

肠道微生物群

The human intestinal microbiota is one of the most densely populated microbial communities on earth. 它包含的基因大约是人类基因组的150倍. 这可能受到基因的影响, 寄主生理和寄主环境因素,如生活方式, 药物,当然还有, 饮食. Dietary fibre and whole grains are associated with increased microbial diversity and shifts can occur in as little as 24 hours after a dramatic change in 饮食ary fibre intake. (Holscher 2017)

什么是肠脑轴?

本质上, 肠脑轴描述了肠脑之间的交流, 由中枢和肠道神经系统促进. Gpk电子游戏现在知道肠道微生物群会影响这些相互作用, 最终影响Gpk电子游戏思考和感受的方式. 肠道细菌可以与肠道细胞和肠道神经系统相互作用, but also on the central nervous system through both neuroendocrine and 代谢 pathways. 现在,肠-脑轴通常被称为微生物群-肠-脑轴.

肠道微生物群是如何影响大脑的?

箭头了

神经递质的产生、表达和转换
保护肠道屏障
肠道感觉神经元的调节
细菌代谢产物
粘膜免疫调节

对大鼠的研究已经证实了微生物群对应激反应的明显影响, 焦虑和抑郁行为, 记忆和学习. 益生菌和益生元已被成功地用于使这些行为正常化. (Zagorska 2020)

大脑是如何影响肠道菌群的?

向下箭头

黏液和生物膜产生的反复
变更的能动性
肠道通透性改变
免疫功能改变

The brain influences the gut in several ways, using both neural and hormonal pathways. 肠道微生物群也影响同样的肠道细胞. 心理压力可以在短短两个小时内影响微生物群. 压力有许多不利影响,包括改变粘膜层, 影响肠蠕动和肠通透性, 和免疫反应. “担心自己不舒服”似乎有一定的生理基础.

当微生物-肠道-大脑轴出现问题时

Adverse composition and diversity of microbiota have been associated with several chronic diseases including colorectal cancer, 代谢, 自身免疫性疾病和过敏性疾病以及神经障碍(Dorelli 2021年). 微生物群失调, 或者肠道菌群失调, 是否与焦虑、抑郁甚至自闭症等神经紊乱有关, 哪些微生物群具有特定变化的特征.

Functional Gastrointestinal Disorders (FGID) with no known cause such as Irritable Bowel Syndrome (IBS), 腹胀, 便秘和腹泻与情绪障碍密切相关. Irritable Bowel Syndrome is now proposed as a disorder of the microbiota-gut-brain axis, 特别是脑-肠-脑功能(而不是肠-脑功能)(Carabotti, 2015).

肥胖中的肠脑轴

越来越多的证据表明,肠道菌群与肥胖有关. People with obesity have different and more adverse microbiota profiles compared to those who are not. 微生物群可能导致肥胖的机制有很多, 包括通过影响胰岛素抵抗, 炎症, 脂肪沉积, 代谢调节, 肥胖, 能量平衡, 食欲和食物奖励信号. The potential for 饮食ary interventions and faecal microbiota transplantation are being investigated as promising 代谢 therapies for healthy weight (Torres-Fuentes, 2017).

The microbiome (the microbiota and their genes) may also help or hinder weight loss. 在一个小型的生活方式干预研究中, researchers identified 31 metagenomic functional features associated with weight loss responses, including the major finding that the ability of the microbiome to break down starches was increased in people who did not lose weight (making more energy available). 在那些减重更多的人身上, 有更多的基因帮助细菌生长得更快, 乘, 复制和组装细胞壁(Diener 2021年).

饮食和微生物群

There is a lack of consensus about what a healthy microbiota should be and there are a multitude of factors at play. Individuals vary in their responses to 饮食ary interventions and effects are hard to disentangle from broader lifestyle, 饮食和环境因素. A review of the effects of 饮食 on the microbiota found good support for probiotics and prebiotics, 多酚也有很好的效果. 嗜酒者体内的微生物群受到不利影响, but studies with alcohol in healthy people are mixed and may involve synergy between polyphenols, 纤维和乙醇——需要更多的研究(Redondo-Useros 2020).

糖,甜味剂和微生物群

There is scarce evidence from human studies evaluating effects of added sugars on the microbiota. Most describe lower bacteria diversity from 饮食s that are generally characterised by energy-dense, 营养物, 含有添加剂的高度加工食品. There are adverse effects on the microbiota of large doses of alternative sweeteners in animal studies, but scant research in humans using realistic amounts within a habitual 饮食 (Redondo-Useros 2020).

益生菌

益生菌, 或者在对宿主有益的食物或补品中存活有益的细菌, 是改善微生物-肠道-大脑轴的关键治疗工具吗. There is potential for specific strains of bacteria to help with different conditions. 例如,有强有力的证据表明存在乳酸菌 这种 用于治疗小儿绞痛,并有乳酸菌的证据 喂食 治疗肠易激综合征(Hojsak 2019). 益生菌 have been investigated for the treatment of psychiatric disorders and a new term ‘psychobiotics’ coined. 在抑郁症状方面已经发现了有希望的结果, 尽管还需要进一步的证据来确定菌株, 剂量, 治疗时间和相互作用(Zagórska, 2020).

益生元

益生元 are the term given to the different types of 饮食ary fibre that can enhance the activity of beneficial microbes, 从而给主人带来好处. Not all 饮食ary fibres are prebiotic- as they need to be fermentable by gut bacteria. Bacteria then produce short chain fatty acids (SCFA) that not only feed the microbiota but are also transported through the bloodstream to affect distant organs. Plant food rich 饮食s can provide a variety of fibre types that support a diverse microbiota. (Holscher 2017).

发酵食品

A review of 19 human intervention studies found promising results that fermented foods (such as kimchi, kefir) can positively modify gut microbiota however more studies are needed to confirm benefit (Stiesma, 2020).

锻炼

锻炼被认为对肠道菌群-肠道-大脑轴有积极的影响. Microbes that produce Short Chain Fatty Acids (SCFA) may have a role in reducing neuro炎症 and mental fatigue, thus offering a mechanistic explanation for the protective benefit of exercise on mental wellbeing. A systematic review identified ten studies and most reported higher variability and prevalence of phylum 厚壁菌门 (健康细菌),特别是运动员(Dorelli 2021).

结论

A healthy and diverse microbiota appears to have many and broad benefits for both physical and mental wellbeing. A balanced and varied plant-based 饮食 with plenty of 饮食ary fibre types along with physical activity and psychological fitness are prudent for beneficial interplay between the gut and the brain.


 参考文献

  • 李晓东,李晓东,李晓东. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. 安杂志. 2015 Apr-Jun; 28 (2): 203 - 209. PMID: 25830558; PMCID: PMC4367209.
  • Diener C, Qin S, Zhou Y et ..al. Baseline Gut Metagenomic Functional Gene Signature Associated with Variable Weight Loss Responses following a Healthy Lifestyle Intervention in Humans. mSystems, 2021; DOI: 10.1128 / mSystems.00964 - 21(开放)
  • 多雷利B, Gallè F, De Vito C, Duranti G等.al. Can Physical Activity Influence Human Gut Microbiota Composition Independently of Diet? 系统回顾. 营养物质. 2021年5月31日,13 (6):1890. doi: 10.3390/nu13061890. PMID: 34072834; PMCID: PMC8228232.
  • 傅瑞斯·杰比,孔兹·瓦a,职员N. 肠道营养物质品尝和信号传导机制II. 肠作为一个感觉器官:神经、内分泌和免疫反应. Am J Physiology 1999; 277: G922-G928. doi / pdf / 10.1152 / ajpgi.1999.277.5.g922
  • Hojsak我. 益生菌在功能性胃肠疾病中的应用. 医学生物学进展. 2019;1125:121-137. doi: 10.1007/5584_2018_321. PMID: 30578460.
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  • Redondo-Useros N, Nova E, González-Zancada N, Díaz LE, Gómez-Martínez S, Marcos A. 微生物群和生活方式:特别关注饮食. 营养物质. 2020年6月15日,12 (6):1776. doi: 10.3390/nu12061776. PMID: 32549225; PMCID: PMC7353459.
  • 王志强,王志强,王志强,王志强. 食用发酵食品会改变人体肠道菌群吗? J减轻. 2020年7月1日,150 (7):1680 - 1692. doi: 10.1093 /约/ nxaa077. PMID: 32232406; PMCID: PMC7330458.
  • Torres-Fuentes C, Schellekens H, Dinan TG, Cryan JF. 肥胖中的微生物-肠道-大脑轴. 《Gpk电子游戏平台》杂志. 2017年10月;2 (10):747 - 756. doi: 10.1016/S2468-1253(17)30147-4. 2017年8月24日. PMID: 28844808.
  • Zagórska A, Marcinkowska M, Jamrozik M, Wiśniowska B, Paśko P. 从益生菌到精神益生菌——精神疾病中的肠脑轴. Benef微生物. 2020年12月2日,11 (8):717 - 732. doi: 10.3920/BM2020.0063. Epub 2020年11月16日. PMID: 33191776.

 

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