Niacin vitamin essentiality

Niacin— An essential B vitamin needed to prevent pellagra. 

The antipellagra vitamin, essential to many animals for growth and health. In humans, niacin is believed necessary, along with other vitamins, for the prevention and cure of pellagra. It functions in protein and carbohydrate metabolism. As a component of two important enzymes, coenzymes I and II, it functions in glycolysis and tissue respiration. 

Niacin (vitamin B3) refers to both nicotinic acid and nicotinamide. Nicotinamide is an essential precursor for the coenzyme nicotinamide adenine dinucleotide (NAD+). 

Pyridine and alkylpyridines are found in coal tar. The monomethyl pyridines (called picolines) undergo side-chain oxidation to carboxylic acids (review Sec. 10.7.b). For example, 3-picoline gives nicotinic acid (or niacin), a vitamin essential in the human diet to prevent the disease pellagra. 

Vitamins are a well-known group of compounds that are essential for human health. Water-soluble vitamins include folate (vitamin B9) to create DNA. Folate also plays an important role in preventing birth defects during early pregnancy. Thiamine is the first vitamin of the B-complex (vitamin Bl) that researchers discovered. It allows the body to break down alcohol and metabolize carbohydrates and amino acids. Like many other B vitamins, riboflavin (vitamin B2) helps the body to metabolize carbohydrates, proteins, and fat. Niacin (vitamin B3) protects the health of skin cells and keeps the digestive system functioning properly. Pantothenic acid (vitamin B5) and biotin allow the body to obtain energy from macronutrients such as carbohydrates, proteins, and fats. Vitamin B6 (pyridoxine) acts as a coenzyme, which means it helps chemical reactions to take place. It also plays a vital role in the creation of nonessential amino acids. 

There are 13 vitamins known to be Important In human nutrition. Included In this class of essential nutrients are vitamin A, B-complex (actually composed of a group of 8 vitamins), vitamin C, vitamin D, vitamin E, and vitamin K. We can subdivide vitamins Into 1) the lipid (fat)-soluble compounds (vitamins A, D, E, and K), meaning they dissolve readily In fat and 2) the water-soluble compounds, vitamin B-complex (thiamin, riboflavin, niacin, vitamin B, panthothenlc acid, vitamin B] 2> biotin, and folic acid) and vitamin C, which dissolves readily In aqueous solutions. It has been three decades since the last vitamin (B] 2) discovered In 1948 and as stated by Herbert (1980), It Is probable that no new vitamins will be found. There are substances which are growth factors for other forms of life, such as bacteria, but not for humans. Para-amlnobenzolc acid (PABA), bioflavonoids (vitamin P), choline. Inositol, llpolc acid, and ubiquinone are just a few of these examples. 

The FCC is to food-additive chemicals what the USP—NF is to dmgs. In fact, many chemicals that are used in dmgs also are food additives (qv) and thus may have monographs in both the USP—NF and in the FCC. Examples of food-additive chemicals are ascorbic acid [50-81-7] (see Vitamins), butylated hydroxytoluene [128-37-0] (BHT) (see Antioxidants), calcium chloride [10043-52-4] (see Calcium compounds), ethyl vanillin [121-32-4] (see Vanillin), ferrous fumarate [7705-12-6] and ferrous sulfate [7720-78-7] (see Iron compounds), niacin [59-67-6] sodium chloride [7647-14-5] sodium hydroxide [1310-73-2] (see lkaliand cm ORiNE products), sodium phosphate dibasic [7558-79-4] (see Phosphoric acids and phosphates), spearmint oil [8008-79-5] (see Oils, essential), tartaric acid [133-37-9] (see Hydroxy dicarboxylic acids), tragacanth [9000-65-1] (see Gums), and vitamin A [11103-57-4]. 

In terms of amino acids bacterial protein is similar to fish protein. The yeast s protein is almost identical to soya protein fungal protein is lower than yeast protein. In addition, SCP is deficient in amino acids with a sulphur bridge, such as cystine, cysteine and methionine. SCP as a food may require supplements of cysteine and methionine whereas they have high levels of lysine vitamins and other amino acids. The vitamins of microorganisms are primarily of the B type. Vitamin B12 occurs mostly hi bacteria, whereas algae are usually rich in vitamin A. The most common vitamins in SCP are thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, choline, folic acid, inositol, biotin, B12 and P-aminobenzoic acid. Table 14.4 shows the essential amino acid analysis of SCP compared with several sources of protein. 

Four of the B vitamins are essential in the citric acid cycle and therefore in energy-yielding metabolism (1) riboflavin, in the form of flavin adenine dinucleotide (FAD), a cofactor in the a-ketoglutarate dehydrogenase complex and in succinate dehydrogenase (2) niacin, in the form of nicotinamide adenine dinucleotide (NAD),... 

A vitamin is defined as an organic compound that is required in the diet in small amounts for the maintenance of normal metabofic integrity. Deficiency causes a specific disease, which is cured or prevented only by restoring the vitamin to the diet (Table 45-1). However, vitamin D, which can be made in the skin after exposure to sunhght, and niacin, which can be formed from the essential amino acid tryptophan, do not stricdy conform to this definition. 

Niacin was discovered as a nutrient during studies of pellagra. It is not strictly a vitamin since it can be synthesized in the body from the essential amino acid tryptophan. Two compounds, nicotinic acid and nicotinamide, have the biologic activity of niacin its metabolic function is as the nicotinamide ring of the coenzymes NAD and NADP in oxidation-reduction reactions (Figure 45-11). About 60 mg of tryptophan is equivalent to 1 mg of dietary niacin. The niacin content of foods is expressed as mg niacin equivalents = mg preformed niacin + 1/60 X mg tryptophan. Because most of the niacin in cereals is biologically unavailable, this is discounted. 

Niacin is also known as vitamin PP or vitamin Bj. The term niacin describes two related compounds, nicotinic acid and nicotinamide (Figure 19.18), both with biological activity. Niacin is formed from the metabolism of tryptophan, and therefore it is not strictly a vitamin. It is a precursor of two cofactors nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are essential for the functioning of a wide range of enzymes involved in redox reactions. 

Riboflavin (vitamin Bj) is chemically specified as a 7,8-dimethyl-10-(T-D-ribityl) isoalloxazine (Eignre 19.22). It is a precnrsor of certain essential coenzymes, such as flavin mononucleotide (FMN) and flavin-adenine dinucleotide (FAD) in these forms vitamin Bj is involved in redox reactions, such as hydroxylations, oxidative carboxylations, dioxygenations, and the reduction of oxygen to hydrogen peroxide. It is also involved in the biosynthesis of niacin-containing coenzymes from tryptophan. 

N.A. Rorippa nasturtium-aquaticum (L.) Hayek. Raphanolide, raphanol, diastase, ferment, gluconasturin, bitters, essential oils, phenyl ethyl, vitamins, niacin.303 A blood builder, antidyskratic diuretic activities, lymphatic and digestive cleansing, treat prostate irritation, vaginal pruritis, chronic skin irritations. 

Several of the B vitamins function as coenzymes or as precursors of coenzymes some of these have been mentioned previously. Nicotinamide adenine dinucleotide (NAD) which, in conjunction with the enzyme alcohol dehydrogenase, oxidizes ethanol to ethanal (Section 15-6C), also is the oxidant in the citric acid cycle (Section 20-10B). The precursor to NAD is the B vitamin, niacin or nicotinic acid (Section 23-2). Riboflavin (vitamin B2) is a precursor of flavin adenine nucleotide FAD, a coenzyme in redox processes rather like NAD (Section 15-6C). Another example of a coenzyme is pyri-doxal (vitamin B6), mentioned in connection with the deamination and decarboxylation of amino acids (Section 25-5C). Yet another is coenzyme A (CoASH), which is essential for metabolism and biosynthesis (Sections 18-8F, 20-10B, and 30-5A). 

Nuts contain minerals such as Mn, Zn, Mg, and K, vitamins including niacin, biotin, and vitamin E, and are also a rich source of essential fatty acids, carbohydrates, and proteins. 

Nicotinic acid (melting point 236°C, density 1.473) and nicotinamide (melting point 129°C, density 1.400) are known as niacin and niacinamide in the food industry. Niacin is the most stable of all vitamins and is essential to humans and animals for growth and health. Niacin and niacinamide are nutritionally equivalent, and compete with one another. 

On the other hand, milk is not only an essential food for infants, but for children and adults as well. Children need sufficient nutrients and energy to meet the demands of growth and development. Demands for nutrients such as protein, Ca, Fe, and Zn are relatively high, and teenagers require quite large amounts of B vitamins - thiamine, riboflavin and niacin. In addition, approximately 45 percent of the adult skeleton is laid down during adolescence. 

The discovery, isolation and final synthesis of a whole group of new compounds essential to health in a balanced diet was another triumph of the chemist. These compounds called vitamins A, Ba or G, C, D, E, K, and several others closely associated with vitamin Ba, such as niacin, pantothenic acid, inositol, para-amino benzoic acid, choline, pyndoxine (Be), biotin (H), folic acid and Bn, prevent deficiency diseases such as xerophthalmia (an eye disease), beriberi, pellagra, scurvy, rickets, sterility (in rats), excessive bleeding and so forth. Professors Elmer V. McCollum and Herbert M. Evans, and Joseph Goldberger were among the early American pioneers in this field of research. Drugs, anaesthetics, and medicines like procaine, cyclopropane, dramamme, ephedrine, aspirin, phenace-tin, urotropin, veronal, quinine, and strychnine have been synthesized to alleviate the pains of mankind. The essential... 

It is not strictly correct to regard niacin as a vitamin. Its metabolic role is as the precursor of the nicotinamide moiety of the nicotinamide nucleotide coenzymes, nicotinamide adenine dinucleotide (NAD) and NADP, and this can also be synthesized in vivo from the essential amino acid tryptophan. At least in developed countries, average intakes of protein provide more than enough tryptophan to meet requirements for NAD synthesis without any need for preformed niacin. It is only when tryptophan metabolism is disturbed, or intake of the amino acid is inadequate, that niacin becomes a dietary essential. 

More than two decades ago I began my search for ways to lower my own cholesterol levels and prevent an early death from heart disease. Certainly, the essential foundation of sueh a program had to include increased physical activity and a heart-healthy diet. But knowing that other factors entered into the cholesterol picture—notably, that the body makes 80 percent of all the cholesterol in the bloodstream—I realized that I needed something more than diet and exercise. My search led me to the soluble fibers in oat bran and other foods that actually flush out cholesterol and the vitamin niacin to stop the body s excessive production of it. Since that time, I ve found additional natural approaches to lowering cholesterol, including the plant sterols known as phytosterols, red yeast rice, and pantethine. 

The organic compounds other than the essential amino acids which are required for health are called vitamins. Man is known to require at least thirteen vitamins Vitamin A, (thiamine), Bo (riboflavin), Bg (pyridoxin), B.o, C (ascorbic acid), D, K, niacin, pantothenic acid, inositol, para-aminobenzoic acid, and biotin. 

Niacin (=nicotinic acid). Just in case you re not convinced that vitamins are everywhere, niacin is part of the NADH and NADPH molecules and thus is vital to numerous reactions in Biocheraistryland. Niacin can be produced from the essential amino acid tryptophan (1-7). 

Red raspberries are one of the plant worlds richest sources of vitamins C and K, the essential mineral manganese, and dietary fiber. Contents of vitamin A (from seed carotenoids), B vitamins 1 through 3 (thiamin, riboflavin, niacin, respectively), iron, calcium, and potassium are also at good levels. 

Small amounts of a vitamin, nicotinic acid, which is often called niacin, occur in all living cells, and it is essential in the nutrition of mammals. It is used in the prevention and treatment of pellagra. 

One of the substances commonly treated as a vitamin is niacin, which is synthesized from the essential amino acid tryptophan. The ratio is approximately 60 mg of tryptophan being required to produce 1 mg of niacin (1). This has led to niacin requirements being expressed as niacin equivalents (NE), based on the amount of tryptophan in the diet. It must be kept in mind that tryptophan is essential and is the precursor to the neurotransmitter serotonin in addition to being part of protein structure. Therefore, niacin can be thought of as tryptophan sparing. 

These compounds are derived from the vitamin niacin (nicotinic acid, nicotinamide) and require it for their synthesis. Small amounts of niacin are derived from the essential amino acid tryptophan. 

Several compounds, e.g., vitamin D and niacin, are apparently required in the diet even though pathways for their synthesis occur in the body. Such a situation may arise if a pathway does not provide an adequate supply for the body s needs or if the material cannot be readily transported from the site of synthesis to the place of action. The compounds discussed below are essential dietary nutrients in one or more nonhuman species, but such a status in humans is not supported by evidence. 

---