Background/Objective: Plant-derived vesicular preparations are a heterogeneous class of products being studied for their potential applications in cancer, inflammatory bowel disease, and metabolic disorders. This review focuses primarily on oncology as a case study while also exploring findings in other non-oncological fields, evaluating the source of the preparations, the causal relationships of their constituents, and the evidence for their translational applications. Methods: On 29 September 2026, we updated the authors’ compiled reference list through a PubMed search of the literature and verified the preparation type, dosage, and mechanism of action in the cited original studies. Results: The existing evidence still primarily stems from preclinical studies. Three tissue-destructive formulations validated by intervention studies provide more informative oncological mechanisms than studies involving only the ingestion process; however, none met the criteria for comprehensive evidence regarding secreted plant-derived vesicles (PDEVs). Across different models, ginger formulations modulate intestinal inflammation and insulin response, while lemon and orange formulations are associated with hepatic redox or metabolic outcomes. These products and their endpoints cannot be consolidated into a single mechanism of action or efficacy assessment. Conclusions: Across various indications, product identity, active dose, target cell exposure, causal intervention, comparators, and the safety of repeated dosing remain essential before clinical claims can be made. Unless new therapeutic uses can be demonstrated, reformulation of existing drugs constitutes merely a formulation improvement.