Abstract: Phytochemicals refer to the bioactive substances present in plants that show specific health-benefiting effects. Due to the poor water solubility, low gastrointestinal stability, low absorption efficiency via intestinal epithelial cells or lymphatic transport, and fast metabolic rate, some phytochemicals exert limited health effects in vivo when orally consumed. Emulsion-based delivery systems can enhance the health effects of phytochemicals in the following ways: 1) by increasing their solubility and stability in the gastrointestinal tract, and preventing them from directly contacting the gastrointestinal environment so as to reduce the degree of degradation; 2) by forming micelles through the oil phase during intestinal digestion to enhance the solubility of lipid-soluble substances in the digestive tract and then improve the absorption efficiency through blood and lymphatic transportation; 3) by regulating the time-delayed release and specific adhesion behavior of phytochemicals in the digestive tract, and changing the structure and function of the intestinal flora or regulating the release and absorption target of phytochemicals to improve their interaction with the intestinal flora. In this paper, the characteristics and advantages of various emulsion systems are reviewed, with special focus on the solubilizing effect of emulsion-based delivery systems on phytochemicals and the effect of emulsion-based delivery systems on their controlled absorption in the digestive tract and interaction with the intestinal flora.

Key words: phytochemicals; delivery systems; digestion and absorption; health-benefiting effects