Niacin dietary

Other Additives. Cats cannot convert tryptophan to niacin (22), or carotene to vitamin A in sufficient amounts to meet thein needs (23). These deviations, as compared with other animals, need not produce problems because added dietary sources of niacin and vitamin A provide the needs of cats. 

The RDA for niacin is based on the concept that niacin coen2ymes participate in respiratory en2yme function and 6.6 niacin equivalents (NE) are needed per intake of 239 kj (1000 kcal). One NE is equivalent to 1 mg of niacin. Signs of niacin deficiency have been observed when less than 4.9 NE/239 kj or less than 8.8 NE per day were consumed. Dietary tryptophan is a rich source of niacin and the average diet in the United States contains 500—1000 mg of tryptophan. In addition, the average diet contains approximately 8—17 mg of niacin. In total, these two quantities total 16—34 NE daily. Table 5 Hsts the RDA and U.S. RDA for niacin (69). 

Niacin is used as adjunctive therapy for the treatment of very high serum triglyceride levels in patients who present a risk of pancreatitis (inflammation of the pancreas) and who do not experience an adequate response to dietary control. 

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. 

Several different niacin formulations are available niacin immediate-release (IR), niacin sustained-release (SR), and niacin extended-release (ER).28,29 These formulations differ in terms of dissolution and absorption rates, metabolism, efficacy, and side effects. Limitations of niacin IR and SR are flushing and hepatotoxicity, respectively. These differences appear related to the dissolution and absorption rates of niacin formulations and its subsequent metabolism. Niacin IR is available by prescription (Niacor ) as well as a dietary supplement which is not regulated by the FDA.28 Currently, there are no FDA-approved niacin SR products, thus, all SR products are available only as dietary supplements. 

Shibata, K. and K. Iwai. 1988. Effect of dietary paraquat on the enzymes involved in tryptophan-niacin metabolism in rats. Agric. Biol. Chem. 52 1857-1858. 

Type V hyperlipoproteinemia requires stringent restriction of dietary fat intake. Drug therapy with fibrates or niacin is indicated if the response to diet alone is inadequate. Medium-chain triglycerides, which are absorbed without chylomicron formation, may be used as a dietary supplement for caloric intake if needed for both types I and V. 

NADP(H) of tryptophan (corn major dietary staple), which supplies a portion of the niacin requirement. 

Parathyroid hormone a peptide hormone that acts to mobilize calcium from bone. Peiiagra a dietary deficiency disease of niacin. 

Oxidation of nicotine with chromic acid led to the isolation of pyridine-3-carboxylic acid, which was given the trivial name nicotinic acid. We now find that nicotinic acid derivatives, especially nicotinamide, are biochemically important. Nicotinic acid (niacin) is termed vitamin B3, though nicotinamide is also included under the umbrella term vitamin B3 and is the preferred material for dietary supplements. It is common practice to enrich many foodstuffs, including bread, flour, corn, and rice products. Deficiency in nicotinamide leads to pellagra, which manifests itself in diarrhoea, dermatitis, and dementia. 

Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin Bg, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington National Academy, 1998. 

Primary chylomicronemia (familial lipoprotein lipase or cofactor deficiency) Chylomicrons, VLDL increased Dietary management (niacin, fibrate) Niacin plus fibrate... 

As described, some persons with familial combined hyperlipoproteinemia have only an elevation in LDL. Serum cholesterol is usually less than 350 mg/dL. Dietary and drug treatment, usually with a reductase inhibitor, is indicated. It may be necessary to add niacin or ezetimibe to normalize LDL. 

Niacin is a generic term which refers to two related chemical compounds, nicotinic acid (6.22) and its amide, nicotinamide (6.23) both are derivatives of pyridine. Nicotinic acid is synthesized chemically and can be easily converted to the amide in which form it is found in the body. Niacin is obtained from food or can be synthesized from tryptophan (60 mg of dietary tryptophan has the same metabolic effect as 1 mg niacin). Niacin forms part of two important co-enzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are co-factors for many enzymes that participate in various metabolic pathways and function in electron transport. 

The classical niacin deficiency disease is pellagra, which is characterized by symptoms including diarrhoea, dermatitis, dementia and eventually death. High-protein diets are rarely deficient in niacin since, in addition to the preformed vitamin, such diets supply sufficient tryptophan to meet dietary requirements. Large doses of niacin can cause the dilation of capillaries, resulting in a painful tingling sensation. 

The RDA for niacin is expressed in terms of energy intake 6.6 mg niacin equivalent (NE, 1 mg niacin or 60 mg tryptophan) per 1000 kcal (4186 kJ) per day is recommended (13NEday-1 minimum). This is approximately equivalent to 19 and 15 mg NE day -1 for men and women, respectively. The UK RNI value for niacin is 6.6 mg NE per 1000 kcal (4186 kJ) per day for adults. The richest dietary sources of niacin are meat, poultry, fish and whole-grain cereals. 

Dietary Deficiency of Niacin, the Vitamin Form of NAD and NADP, Causes Pellagra... 

Vitamins are chemically unrelated organic compounds that cannot be synthesized by humans and, therefore, must must be supplied by the diet. Nine vitamins (folic acid, cobalamin, ascorbic acid, pyridoxine, thiamine, niacin, riboflavin, biotin, and pantothenic acid) are classified as water-soluble, whereas four vitamins (vitamins A, D, K, and E) are termed fat-soluble (Figure 28.1). Vitamins are required to perform specific cellular functions, for example, many of the water-soluble vitamins are precursors of coenzymes for the enzymes of intermediary metabolism. In contrast to the water-soluble vitamins, only one fat soluble vitamin (vitamin K) has a coenzyme function. These vitamins are released, absorbed, and transported with the fat of the diet. They are not readily excreted in the urine, and significant quantities are stored in Die liver and adipose tissue. In fact, consumption of vitamins A and D in exoess of the recommended dietary allowances can lead to accumulation of toxic quantities of these compounds. 

This value includes niacin equivalents from preformed niacin and from tryptophan. A dietary intake of 60 mg tryptophan is considered equivalent to 1 mg niacin. One niacin equivalent is equal to either to those amounts. 

Niacm - piTAMINS - NIACINE,NICOTINAMIDEAND NICOTINIC ACID] (Vol 25) - [FEEDS AND FEED ADDITIVES - PET FOODS] (Vol 10) - [FINECHEMICALS - PRODUCTION] (Vol 10) - [FEEDS AND FEED ADDITIVES - RUMINANT FEEDS] (Vol 10) -m dairy substitutes pAIRY SUBSTITUTES] (Vol 7) -m dairy substitutes pAIRY SUBSTITUTES] (Vol 7) -deficiency of piTAMINS - NIACINE,NICOTINAMIDEAND NICOTINIC ACID] (Vol 25) -dietary requirements piTAMINS - NIACINE, NICOTINAMIDE AND NICOTINIC ACID] (Vol 25) -m nuts PUTS] (Vol 17) -m nuts PUTS] (Vol 17)... 

In food technology, the addition to a foodstuff of various nutrient substances during manufacture to increase the dietary value of the food, e.g.. addition to wheat Hour of vitamins B. By. niacin, and iron. In (his way. the food is brought up to specific nutritional standard. 

The desugaring of cane juice concentrates the heat- and alkali-stable vitamins in the final molasses. Even after this accumulation, only myo-inositol may have reached the level of minimum dietary requirements.109 Niacin, pantothenic acid and riboflavin are also present in significant quantities109 the thiamine, pyridoxin, pantothenic acid, biotin and folic acid contents of molasses have been estimated by bioassay.110 111 The biotin content of Hawaiian and Cuban molasses was 2.1 and 1.7 gammas per gram, respectively.119 The antistiffness factor (closely related to stigmasterol) has been found in cane molasses.88 89 The distillery slop from the yeast fermentation of molasses is marketed as a vitamin concentrate this product also contains vitamins originating in the yeast. 

A number of nutrients of lesser dietary significance are present in orange juice and other citrus juices. Measurable levels of Vitamin A, riboflavin (Vitamin B2), niacin, pyridoxine (Vitamin B5) and pantothenic acid have been reported in orange juice. The levels of these nutrients are generally in the range of 2-3% of their respective U.S. RDA s. For a more extensive review of these nutrients, one should consult Ting (23) and Araujo (33). 

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