Vitamins, continued water-soluble

The B group of vitamins covers water-soluble vitamins, all of which serve as precursors for coenzymes. Their numbering sequence is not continuous, as many substances that were originally regarded as vitamins were not later confirmed as having vitamin characteristics. 

This product is an aqueous solution of water-soluble vitamins with oily vitamin A palmitate and cholecalceferol solubilized in water using the surfactant system of Tween 80 and Cetomacrogol. This syrup is a solubilized oil surfactant system and is liable to heat and rate of mixing. The temperature of solution must not exceed 30°C at the time of final mixing. The final mixing must be in continuous manner without any interruption. For the preparation of oily phase, the container must be dry. 

Vitamin C continues to be the water-soluble vitamin upon which the bulk of the method development attention is focused. The HPLC methods published from 1992 to 1997 for total vitamin C... 

During the course of the symposium, several dietary factors that can influence xenobiotic metabolism were discussed in detail. Here we will attempt t summarize in the broadest terms how various classic nutrient groups might exert an influence on xenobiotic metabolism. For convenience, the dietary groups have been broken into carbohydrates, lipids, proteins, water-soluble vitamins, fat-soluble vitamins and trace elements. It is difficult to take any one group individually, and it must be kept in mind that the interactions are continuous and extremely complicated. 

Biotin is a water-soluble vitamin. It is a cofactor for four ATP-dependent carboxylases acetyl-CoA carboxylase, pyruvate carboxylase, propionyl-CoA carboxylase, and p-methylcrotonyl-CoA carboxylase. Biotin occurs covalently bound to the enzymes via the terminal amino group of a lysine residue. With the normal and continual turnover of these enzymes in the body, the biotin is released, but then utilized again as a cofactor when the enzymes are re-synthesized. The structure of biotin is shown in Figure 9.32,... 

Water-soluble vitamins are absorbed in water in the small intestine and excreted in urine, except for folic acid. They are not stored in the body therefore, the body requires a continuous supply of water-soluble vitamins. 

Fig. 4.19 Continuous solid-liquid extraction assembly for the determination of water-soluble vitamins in pharmaceuticals as a preliminary step to their introduction into a liquid chromatograph. (Reproduced from [15] with permission of Francis 4 Taylor Ltd.).

The diffusion studies described in the above sections pertain to water-continuous and bicontinuous microemulsions. Chen and Georges [34] were the first to study diffusion in oil-continuous microemulsions using steady-state microelectrode voltammetry. Ferrocene was used to probe diffusion in an SDS-dodecane-1-heptanol-water system. The diffusion coefficient of the hydrophobic probe indicated the microviscosity of the oil rather than the bulk viscosity of the microemulsion. Owlia et al. [36] reported diffusion coefficient measurements of water droplets in an Aerosol OT [AOT, bis(2-ethylhexyl)sulfosuccinate] microemulsion using a microelectrode. Water-soluble cobalt(II) corrin complex (vitamin Bi2r) was used in an oil-continuous microemulsion containing 0.2 M AOT, 4 M water buffered at pH 3, and isooctane. The apparent diffusion coefficient decreased with the probe concentration in accordance with Eq. (13) as shown in Fig. 6 [36]. The water droplet size was... 

Proponents of this vitamin therapy often understand the risks of vitamin overdose. The scientific literature reports several well documented cases, sometimes with fatal consequences. Fat-soluble vitamins are of the Itighest concern in this respect, both acute (a single extremely large dose) or chrotuc (from continuous large doses) toxicity is known for them. It is not an accident that three of the four fat-soluble vitamins have widely accepted UL values, whereas water-soluble vitamins rarely have rehably known upper hmits. Studies of both hypo- and hyper-vitantin-osis contain enough scientific literature to fill libraries, and this short stoiy carmot even scratch the surface. Table 3.4 displays a few vitamins with reliable UL values and lists the symptoms of overdose. Care must be taken, as the toxic dose is usually lower for children than for adults, and the symptoms in kids may be more serious. 

As discussed before (2), multiple emulsions (w/o/w or o/w/o) are ideal systems for application in personal care products for the following reasons. First, one can dissolve ingredients in three different compartments. For example with w/o/w multiple emulsions, one can incorporate two different water-soluble additives (proteins, enzymes, and vitamins) and an insoluble ingredient (e.g., perfume). Second, they can be applied for sustained release by control of the breakdown process that occurs on application. Third, they allow one to produce the same cream consistency required for many cosmetics, e.g., by incorporation of a thickener or gelling agent in the outer continuous phase. 

Vitamin B12 (cobalamine) is needed to metabolize fatty adds and amino acids and to synthesize DNA in cells. Vitamin C also has several functions. It is needed to synthesize collagen, the most abundant protein in the body, but it also acts as an antioxidant, helping to reduce the risk of developing chronic diseases like heart disease and cancer. Water-soluble vitamins are not stored in the body. Because they are eliminated in urine, a continuous daily support through diet is required. However, even foods that contain the necessary vitamins can have reduced vitamin content after storage, processing, or cooking. Therefore, many people take a multivitamin tablet to supplement their diet. To ensure that these tablets contain the labeled amounts of vitamins, there must be a quality control assay for these tablets. 

Assay of B Vitamins and other Water-soluble Vitamins in Honey Table 13.2 Continued)... 

Organic nutrients also include vitamins. Inorganic chemical compounds, such as dietary minerals, water (and oxygen), may also be considered nutrients. Vitamins and dietary minerals are collectively known as accessory (additive) nutrients and are often referred to as essential nutritional factors. With the exception of some vitamins that humans cannot synthesise, these accessory nutrients must be obtained from foods. They are therefore known as exogenous factors. Another essential nutrient is water, which is obtained in small amounts by oxidation of primary nutrients, but in much larger quantities from foods, and especially from beverages. Most foods contain a mixture of some or aU of the nutrient classes, together with many other substances. Some nutrients can be stored internally (such as the fat soluble vitamins), while others are required more or less continuously. Poor health maybe caused by a lack of required nutrients or, in extreme cases, too much of a required nutrient. 

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