Regulation of Intracellular Lipid Droplets by Tea: Mechanistic Insights and Food Applications

Lipid droplets (LDs) are central organelles governing lipid metabolism, and their dynamics (including formation, expansion, and degradation) are closely linked to systemic lipid homeostasis. Tea has been demonstrated to alleviate lipid metabolic disorders, potentially through its regulatory on LDs. Tea enhances the abundance of Lachnoclostridium, promoting the production of lysophosphatidylethanolamine (LPE), lysophosphatidylcholine (LPC), and phosphatidylinositol (PtdIns). Concurrently, tea elevates the levels of butyric acid by enriching Blautia, Allobaculum, and Bifidobacterium, thereby contributing to elevated phosphatidylcholine (PC) synthesis. Tea-derived tryptophan is metabolized by Clostridiaceae, Bacteroidales S24-7 group, and Lactobacillaceae into indole-3-propionic acid, which activates the aryl hydrocarbon receptor and upregulates Pemt via the insulin/protein kinase B signaling pathway, facilitating phosphatidylethanolamine (PE)-to-PC conversion. In parallel, tea promotes Prevotella, Bacteroides, and Muribaculaceae, while suppressing Desulfovibrio, favoring a reduction in PE levels. Collectively, these alterations reshape the phospholipid composition of the LD monolayer, characterized by increased proportions of LPE, LPC, PtdIns, and PC and reduced PE. This shift elevates the Γ²/γ (Γ, line tension; γ, surface tension) ratio, limits LD fusion, and increases LD-specific surface area, thereby enhancing lipolytic enzyme access to stored triglycerides. The primary aim of this review is to systematically clarify the molecular mechanisms by which tea regulates LD dynamics and to examine its translational potential in the food sector. We summarize the molecular basis of LD dynamics, how tea modulates the gut microbiota and LD phospholipid composition, the signaling pathways involved in LD homeostasis, and applications of these mechanisms in food, including optimizing nanoemulsions and achieving targeted LD regulation through enhanced tea bioactivity.