Vitamin A fortification: Recent advances in encapsulation technologies

Vitamin A is an essential micronutrient whose deficiency is still a major health concern in many regions of the world. It plays an essential role in human growth and development, immunity, and vision, but may also help prevent several other chronic diseases. The total amount of vitamin A in the human diet often falls below the recommended dietary allowance of approximately 900-1000 μ $ \umu $ g/day for a healthy adult. Moreover, a significant proportion of vitamin A may be degraded during food processing, storage, and distribution, thereby reducing its bioactivity. Finally, the vitamin A in some foods has a relatively low bioavailability, which further reduces its efficacy. The World Health Organization has recommended fortification of foods and beverages as a safe and cost-effective means of addressing vitamin A deficiency. However, there are several factors that must be overcome before effective fortified foods can be developed, including the low solubility, chemical stability, and bioavailability of this oil-soluble vitamin. Consequently, strategies are required to evenly disperse the vitamin throughout food matrices, to inhibit its chemical degradation, to avoid any adverse interactions with any other food components, to ensure the food is palatable, and to increase its bioavailability. In this review article, we discuss the chemical, physical, and nutritional attributes of vitamin A, its main dietary sources, the factors contributing to its current deficiency, and various strategies to address these deficiencies, including diet diversification, biofortification, and food fortification.

The Effect of Cholesterol in the Liposome Bilayer on the Stabilization of Incorporated Retinol

The effect of cholesterol in the liposome bilayer on the stability of incorporated retinol was studied. Retinol was incorporated into liposomes containing soybean phosphatidylcholine (PC) and cholesterol (CH) at various ratios, and the liposomes were prepared as multilamellar vesicles by the dehydration-rehydration method. Retinol readily incorporated into liposomes at a ratio of 0.01:1 (w/w) retinol:lipid, with over 94.52% being incorporated in all conditions studied. The incorporation efficiency of retinol increased slightly with increasing CH content in the liposome and with increasing pH of the hydration buffer. Average particle size increased as the CH content increased, and mean particle sizes at pH 5, 7, and 9 were 30.27, 89.53, and 41.42 microm, respectively. The time course of retinol degradation in aqueous solution in liposomes with various ratios of PC to CH was determined under a variety of pH conditions (pH 5, 7, and 9), and temperatures (4, 25, 37, and 50 degrees C). The stability of incorporated retinol was enhanced by increasing the CH content. At pH 7.0 and 4 degrees C, for example, 90.17% of the retinol in liposomes containing 50:50 (PC:CH) remained after 10 days of storage, whereas 51.46% remained at 100:0 (PC:CH). These results indicate that CH in liposomes greatly increases the incorporation efficiency of retinol and the stability of incorporated retinol.