Handbook of Vitamin C Research

188Magdalena Stevanović and Dragan Uskoković3.1. Water- Soluble VitaminsWater-soluble vitamins dissolve easily in water, and in general, are readily excreted fromthe body, to the degree that urinary output is a strong predictor of vitamin consumption [38-40].The water-soluble vitamins, excluding vitamin C, popularly are termed the B-complexvitamins. There are eight of them, namely; B1 (thiamine), B2 (riboflavin), B3 (niacin), B6(pyridoxine), B9 (folic acid), B12 (cobalamin), pantothenic acid, and biotin [41-43]. Eachnutrient in the B vitamin complex performs a unique role in maintaining proper metabolicfunctioning and is essential for well-being. Vitamin C (ascorbic acid) is one of the mostimportant water-soluble vitamins in biological systems. Vitamin C is well-known for itssuperior antioxidant power and is the leading vitamin for immune support. Because watersolublevitamins are not readily stored, consistent daily intake is important.4. Vitamin CL-ascorbic acid (C 6 H 8 O 6 ) is the trivial name of vitamin C. The chemical name is 2-oxo-L-threo-hexono-1,4-lactone-2,3-enediol [44,45]. L-ascorbic and dehydroascorbic acid are themajor dietary forms of vitamin C (Figure 1). Ascorbic acid is a six-carbon lactone with amolecular weight of 176.13g/mol (Figure 1). All commercial forms of ascorbic acid exceptascorbyl palmitate are soluble in water [46].L-ascorbic acid and its fatty acid esters are used as food additives, antioxidants,browning inhibitors, reducing agents, stabilizers, etc. Ascorbyl palmitate has been used for itsgreater lipid solubility in antioxidant preparations. pH has a great influence on stability ofascorbic acid [46-48]. Most of the plants and animals synthesize ascorbic acid from D-glucose or D-galactose (Figure 2). A majority of animals produce relatively high levels ofascorbic acid from glucose in liver [46].Figure 1. L-Ascorbic acid.