Background: Both pleiotropic and ubiquitous, microRNAs (miRNAs) exert control over a wide range of cellular functions. They have been detected in virtually every extracellular fluid in the mammalian body, and many circulate substantial anatomical distances in plasma. Thus, secreted miRNAs are valuable not only as diagnostic tools but also may serve as novel biological effectors that can be transmitted between source and recipient tissue. Design: This review will discuss the possibility of delivering functional miRNAs from exogenously derived dietary sources. We will examine prior research interrogating the existence and relevance of such a mechanism. Findings: Recent findings have reported cross-kingdom transfer of specific plant-derived miRNAs to mammalian tissue following consumption of plant-based foods. These exogenous miRNAs were reported to be active in the recipient organisms, directing changes in gene expression at distant organ sites. In spite of this, subsequent studies have been unable to find evidence of substantial exogenous diet-derived miRNAs in mammalian circulation or tissues, regardless of diet. Conclusion: Further examination of diet-derived miRNA uptake is ongoing, but it does not appear that horizontal delivery of miRNAs via normal dietary intake is a generalizable or frequent process to maintain robust expression of these miRNAs in most higher-order animal organisms.