Background

Short-chain fatty acids (SCFAs) play important physiological roles in human health. Adverse effects on health are known with a low or excessive concentration of SCFAs although the optimal level of SCFAs in the body is unknown yet. The level of endogenous SCFAs is affected by many factors of which gut bacteria are the most important one. However, how gut bacteria and a dietary intervention affect SCFA balance in the gut still needs to be clarified.

Scope and approach

In addition to addressing the importance of a dynamic balance of SCFAs for health, we discuss the factors affecting the dynamic balance of SCFAs, especially the gut SCFA-producing bacteria, including the classification of the bacteria, their response to diet, the SCFAs metabolic pathways and the catalytic mechanisms of the main rate-limiting enzymes.

Key findings and conclusions

SCFAs levels can be regulated endogenously and exogenously. Exogenous regulation delivers SCFAs to gut by esterification with dietary fibres. Endogenous regulation like diet, directly or indirectly affect gut microbiota, including their abundance, fitness and SCFAs production. Until now, 74 bacterial species are reported to produce SCFAs, the metabolic pathways are classified into 4 categories, and the 4 rate-limiting enzymes in the metabolic pathways are summarized. We also propose methods for long-lasting endogenous SCFAs balancing, including identifying the minimum sets of SCFA-producing bacterial group, and possible dietary intervention to form a minimum group of gut microbiota for SCFAs synthesis. An integrated approach will help realize the rational regulation of balanced SCFAs levels to benefit human health.

中文翻译：

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肠道短链脂肪酸的动态平衡：细菌代谢的关键作用

背景

短链脂肪酸（SCFA）在人类健康中起着重要的生理作用。众所周知，SCFA浓度过低或过高都会对健康产生不利影响，尽管目前尚不清楚体内SCFA的最佳水平。内源性SCFA的水平受多种因素影响，其中肠道细菌是最重要的因素。但是，肠道细菌和饮食干预如何影响肠道中的SCFA平衡仍需要弄清楚。

范围和方法

除了解决SCFA动态平衡对健康的重要性外，我们还讨论了影响SCFA动态平衡的因素，尤其是肠道SCFA产生细菌，包括细菌的分类，它们对饮食的反应，SCFA代谢途径。以及主要的限速酶的催化机理。

主要发现和结论

SCFA水平可以内源性和外源性调节。外源调节通过用膳食纤维酯化将SCFA输送到肠道。饮食等内源性调节直接或间接影响肠道菌群，包括其丰富度，适应性和SCFA的产生。迄今为止，据报道有74种细菌产生SCFA，其代谢途径分为4类，总结了代谢途径中的4种限速酶。我们还提出了用于持久内源性SCFA平衡的方法，包括确定产生SCFA的细菌组的最小集，以及可能的饮食干预以形成用于SCFA合成的肠道菌群的最小组。一种综合方法将有助于实现合理平衡SCFA含量的合理调节，从而有益于人类健康。