The health promotion properties of polyphenols have attracted a lot of attention in recent years because their biological and pharmacological effects including antioxidative, anticancer, and chronic disease prevention properties have been demonstrated in numerous animal, human, and in vitro studies. One of the major challenges of polyphenols is their poor stabilities and low oral bioavailabilities. Nanoemulsions are a class of extremely small emulsion droplets usually in the range of 50-200 nm, much smaller than the sizes (from 1 to 100 μm) of normal emulsions. Nanoemulsions offer advantages of excellent stability to encapsulate active compounds due to their small droplet sizes and high kinetic stability. High- pressure homogenized nanoemulsions formed by various amounts of water, oil, and emulsifiers were prepared, and their microstructure and size were measured using an inverted optical microscope and particle size analyzer, respectively. The pH and long-term stabilities of polyphenols including epigallocatechin gallate (EGCG) and curcumin encapsulated in nanoemulsions were evaluated by HPLC analysis and UV. The antiinflammation and antitumor functions of nanoemulsion- encapsulated polyphenols were tested in mice. The results suggest that nanoemulsions could improve stability and oral bioavailability of EGCG and curcumin.