Niacin nutrition

The two methods of assessing niacin nutritional status are measurement of blood nicotinamide nucleotides and the urinary excretion of niacin metabolites, neither of which is wholly satisfactory. 

Measurement of liver and other tissue concentrations of NAD(P) gives a precise estimate of niacin nutritional status and seems to be the most sensitive indicator in experimental animals. Measurement of the whole blood concentration of NAD (P) may serve the same purpose there is a good correlation between blood and liver concentrations of nicotinamide nucleotides in experimental animals. The sensitivity of the method is such that reproducible determinations can be carried out on finger-prick samples of 200 /xL of blood (Bender etal., 1982). 

Erythrocyte NAD falls during niacin depletion and rises during repletion in human subjects. Erythrocyte NADP is unaffected, and the ratio of NADiNADP provides a useful index of niacin nutritional stams, with a ratio <1.0 indicating deficiency (Fu et al., 1989). 

The most widely used method for assessing niacin nutritional status is measurement of the urinary excretion of niacin metabolites. Table 8.1 shows the excretion of A( -methyl nicotinamide and methyl pyridone carboxamide in niacin adequacy and deficiency. 

Bender DA (1996) Tryptophan and niacin nutrition - is there a prohXemI Advances in Experimental Medicine and Biology 398, 565-9. 

Fu CS, Swendseid ME, Jacob RA, and McKee RW (1989) Biochemical markers for assessment of niacin nutritional status in young men levels of erythrocyte niacin coenzymes and plasma tryptophan./owraa/o/JVMtrifton 119,1945-9. 

Indices of Riboflavin Nutritional Status Reference Intakes of Riboflavin Indices of Niacin Nutritional Status Reference Intakes of Niacin... 

The excretion of methyl pyridone carboxamide is more severely reduced in marginal niacin deficiency than is that of -methyl nicotinamide. The excretion of methyl pyridone carboxamide decreases rapidly in subjects fed on a niacin-deficient diet, and virtually ceases several weeks before the appearance of clinical signs of deficiency by contrast, a number of studies have shown continuing excretion of -methyl nicotinamide even in pellagrins. A better estimate of niacin nutritional status can be obtained by determining the ratio of urinary methyl pyridone carboxamide Ai -methyl nicotinamide, which is relatively constant, despite the administration of loading doses of tryptophan or niacin to adequately nourished subjects (between 1.3 to 4.0), and a ratio of less than 1.0 indicates depletion of niacin reserves (de Eange and Joubert, 1964 Dillon et al., 1992). 

Biochemistry of NAD NAD Used for Nonredox Purpose History of Niacin Nutrition Ass sment of Niacin Static Pharmacological Use of Nicotinic Add Thiamin... 

Sandhu JS, Fraser DR. Measurement of niacin metabolites in urine by high pressure liquid chromatography. A simple, sensitive assay of niacin nutritional status. Int J Vitam Nutr Res 1981 51 139-44. 

Olsson, A.G., 2010b. HDL and LDL as therapeutic targets for cardiovascular disease prevention the possible role of niacin. Nutrition, Metabolism Cardiovascular Disease. 20 553-557. 

K Shibata, K Murata. Blood NAD as an index of niacin nutrition. Nutr Int 2 177-181, 1986. 

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