Butyrate, a four‐carbon short‐chain fatty acid (SCFA), is a metabolite of anaerobic bacteria. Butyrate has primarily been described as an energy substance in the studies on the digestive tract. The multiple mechanisms of its protective function in the gut and on underlying diseases (including metabolic diseases, diseases of the nervous system, and osteoporosis) via interaction with intestinal epithelial cells and immune cells have been well documented. There are many butyrogenic bacteria in the oral cavity as well. As essential components of the oral microbiome, periodontal pathogens are also able to generate butyrate when undergoing metabolism. Considerable evidence has indicated that butyrate plays an essential role in the initiation and perpetuation of periodontitis. However, butyrate is considered to participate in the pro‐inflammatory activities in periodontal tissue and the reactivation of latent viruses. In this review, we focused on the production and biological impact of butyrate in both intestine and oral cavity and explained the possible pathway of various diseases that were engaged by butyrate. Finally, we suggested two hypotheses, which may give a better understanding of the significantly different functions of butyrate in different organs (i.e., the expanded butyrate paradox).

中文翻译：

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一把双刃剑：丁酸酯在口腔和肠道中的作用

丁酸盐是一种四碳短链脂肪酸（SCFA），是厌氧细菌的代谢产物。丁酸盐在消化道研究中主要被描述为一种能量物质。通过与肠上皮细胞和免疫细胞相互作用，其在肠道和基础疾病（包括代谢性疾病，神经系统疾病和骨质疏松症）中具有多种保护功能的机制已得到充分证明。口腔中还有许多产热细菌。作为口腔微生物组的重要组成部分，牙周病原体在进行新陈代谢时也能够生成丁酸。大量证据表明，丁酸酯在牙周炎的引发和永存中起着至关重要的作用。然而，丁酸酯被认为参与牙周组织的促炎活性和潜伏病毒的重新激活。在这篇综述中，我们重点研究了丁酸盐在肠道和口腔中的产生及其生物学影响，并解释了丁酸盐参与的各种疾病的可能途径。最后，我们提出了两个假设，它们可以更好地理解丁酸酯在不同器官中的显着不同的功能（即，扩展的丁酸酯悖论）。