Encapsulation of Nutraceuticals and Vitamins

Fat-soluble bioactive substances, such as nutraceuticals and vitamins, often have unfavorable properties for use in dietary supplements and cosmetics. Many are unstable to oxygen, ultraviolet light, and heat; as they are hydrophobic, they are less soluble in water, which leads to poor bioavailability. Therefore, systematic studies have been conducted on improving the stability, water solubility, and bioavailability of fat-soluble substances by complexation with cyclodextrin (CD). Molecules of a fat-soluble substance aggregate in water, so they are difficult to dissolve. In addition, when a fat-soluble substance is orally ingested, it is difficult to take up with micelles of bile acid in the intestinal tract, so its bioavailability is extremely low. In contrast, a fat-soluble substance–γ-CD complex incorporates molecules of the fat-soluble substance in the γ-CD cavity one by one, and it disperses well in water. When this complex is taken orally, it replaces the bile acid–γ-CD complex in the intestinal tract, at which time one molecule of the fat-soluble substance is released from the complex. This fat-soluble substance released is taken up rapidly by micelles of bile acid and absorbed in the body. As a result, ingestion of the γ-CD complex enhances the bioavailability of the fat-soluble substance. This innovative encapsulation with γ-CD improves the bioavailability of nutraceuticals and vitamins, and it can be applied to a variety of fat-soluble bioactive substances, such as coenzyme Q10, curcumin and δ-tocotrienol (vitamin E).