MicroRNAs (miRNAs) are short, non-coding, single-strand RNA molecules that act as regulators of gene expression in plants and animals. In 2012, the first evidence was found that plant miRNAs could enter the bloodstream through the digestive tract. Since then, there has been an ongoing discussion about whether miRNAs from the diet are transferred to blood, accumulate in tissues, and regulate gene expression. Different research groups have tried to replicate these findings, using both plant and animal sources. Here, we review the evidence for and against the transfer of diet-derived miRNAs from plants, meat, milk and exosome and their assimilation and putative molecular regulation role in the consuming organism. Some groups using both miRNAs from plant and animal sources have claimed success, whereas others have not shown transfer. In spite of the biological barriers that may limit miRNA transference, several diet-derived miRNAs can transfer into the circulating system and targets genes for transcription regulation, which adds arguments that miRNAs can be absorbed from the diet and target specific genes by regulating their expression. However, many other studies show that cross-kingdom transfer of exogenous miRNAs appears to be insignificant and not biologically relevant. The main source of controversy in plant studies is the lack of reproducibility of the findings. For meat-derived miRNAs, studies concluded that the miRNAs can survive the cooking process; nevertheless, our evidence shows that the bovine miRNAs are not transferred to human bloodstream. The most important contributions and promising evidence in this controversial field is the transference of milk miRNAs in exosomes and the finding that plant miRNAs in beebread regulate honeybee caste development, and cause similar changes when fed to Drosophila. MiRNAs encapsulated in exosomes ensure their stability and resistance in the harsh conditions presented in milk, bloodstream, and gastrointestinaltract to reinforce the idea of transference. Regardless of the model organism, the idea of source of miRNAs, or the approach—bioinformatics or in vivo—the issue of transfer of miRNAs from the diet remains in doubt. Our understanding of the cross-kingdom talk of miRNAs needs more research to study the transfer of “xenomiRs” from different food sources to complement and expand what we know so far regarding the interspecies transfer of miRNAs.

中文翻译：

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miRNAs从饮食转移到血液的证据仍然没有定论

MicroRNA (miRNA) 是短的、非编码的单链 RNA 分子，在植物和动物中充当基因表达的调节剂。2012 年，第一个证据表明植物 miRNA 可以通过消化道进入血液。从那时起，关于饮食中的 miRNA 是否会转移到血液中、在组织中积累并调节基因表达的讨论一直在进行。不同的研究小组尝试使用植物和动物来源复制这些发现。在这里，我们回顾了支持和反对饮食来源的 miRNA 从植物、肉类、牛奶和外泌体转移的证据，以及它们在消费生物中的同化和假定的分子调节作用。一些使用来自植物和动物来源的 miRNA 的小组声称取得了成功，而其他小组则没有表现出转移。尽管存在可能限制 miRNA 转移的生物学障碍，但几种饮食来源的 miRNA 可以转移到循环系统中并靶向基因进行转录调控，这增加了 miRNA 可以从饮食中吸收并通过调节其表达来靶向特定基因的论点。然而，许多其他研究表明，外源 miRNA 的跨界转移似乎无关紧要，并且与生物学无关。植物研究中争议的主要来源是研究结果缺乏可重复性。对于肉类衍生的 miRNA，研究得出的结论是 miRNA 可以在烹饪过程中存活；尽管如此，我们的证据表明牛 miRNA 不会转移到人类血液中。在这个有争议的领域，最重要的贡献和最有希望的证据是外泌体中牛奶 miRNA 的转移，以及蜜蜂面包中的植物 miRNA 调节蜜蜂种姓发育，并在喂食果蝇时引起类似变化的发现。封装在外泌体中的 miRNA 确保它们在牛奶、血液和胃肠道中的恶劣条件下的稳定性和抵抗力，以加强转移的想法。无论是模型生物、miRNA 来源的想法，还是方法（生物信息学或体内），从饮食中转移 miRNA 的问题仍然存在疑问。我们对 miRNA 的跨界讨论的理解需要更多的研究来研究“xenomiRs”从不同食物来源的转移，以补充和扩展我们迄今为止对 miRNA 的种间转移的了解。