Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998) / Chapter Skim
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6 Niacin
6 Niacin
Pages 123-149
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From page 123... ...
for niacin is the urinary excretion of niacin metabolites. No adjustment is made for bioavailability, but the requirement is expressed in niacin equivalents (NEs)
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From page 124... ...
repair and calcium mobilization (Kim et al., 1994; Lautier et al., 1993; Lee et al., 1989~. The amino acid tryptophan is converted in part to nicotinamicle and thus can contribute to meeting the requirement ~ · .
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From page 125... ...
The bocly's niacin requirement is met not only by nicotinic acid and nicotinamincle present in the cliet, but also by conversion from the clietary protein containing tryptophan. The relative contribution of tryptophan is estimated as follows: 60 mg of tryptophan = 1 mg of niacin = 1 mg of niacin equivalents (Horwitt et al., 1981~.
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From page 126... ...
The ratio of the 2-pyridone to Ni-methyl-nicotinamide, although independent of age and creatinine excretion, is a measure of protein acloquacy rather than niacin status (Shibata and Matsuo, 1989~. It is relatively insensitive to a marginal niacin intake of 10 mg/ciay of niacin equivalents (NEs)
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From page 127... ...
Plasma concentrations of other niacin metabolites and of niacin are not useful markers of niacin status. Erythro~te Pyr~dine Nucleotides Analysis of erythrocyte NAD concentration promises to be a sensitive indicator of niacin clepletion.
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From page 128... ...
Conversion efficiency may increase with some clietary restrictions because of changes in activities of pathway enzymes including tryptophan oxygenase, quinolinate phosphoribosyltransferase, and picolinate carboxylase. The requirement for preformed niacin as a proportion of the total niacin requirement tends to be lower with higher tryptophan intakes (a greater proportion of tryptophan is available for conversion to NAD once protein synthesis needs are met)
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From page 129... ...
Studies of niacin requirements are consistently presented in relation to energy intake on the basis of the known biochemical function of niacin, as have been past recommenciations for niacin intake (NRC, 1989~.* fit is recognized that studies of individuals in forced starvation situations have reported that individuals with the greatest initial body weights (and thus the greatest energy expenditure)
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From page 130... ...
FINDINGS BY LIFE STAGE AND GENDER GROUP Infants Ages O through I2 Months Method Used to Set the Adequate Intake As for other nutrients, the Acloquate Intake (AI) level for niacin is set for infants baseci on the observed mean intake of infants feci principally with human milk.
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From page 131... ...
Thus the AI for niacin given in NEs is 4 mg/ciay for infants ages 7 through 12 months the value extrapolated from estimates of adult requirements. Niacin Al Summary, Ages O through I2 Months AI for Infants 0-6 months 2 mg/day of preformed niacin 7-12 months 4 mg/day of niacin equivalents ~0.2 mg/kg ~0.4 mg/kg Children and Adolescents Ages ~ through IS Years Method Used to Estimate the Average Requirement No ciata were found on which to base the EAR for niacin for children or adolescents.
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From page 132... ...
Excretion of Ni-methyl-nicotinamide rather than the 2-pyridone derivative is preferred as the target measure for estimating the niacin requirement because this metabolite better differentiates marginal from acloquate niacin intakes Jacob et al., 1989) , interpretive guidelines exist for this metabolite (ICNND, 1963)
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From page 133... ...
Urinary Ni-methyl-nicotinamicle excretion was found to be 0.6 mg/ciay in three females on corn-baseci, niacin-cleficient cliets that resulted in clinical signs and symptoms of pellagra Goldsmith et al., 1952, 1955~. A urinary excretion value for Ni-methylnicotinamicle of 1.0 mg/ciay has been chosen as an interpolated level of niacin excretion; it reflects a niacin intake that is above the intake that results in clinical niacin deficiency and thus is minimal or barely acloquate.
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From page 135... ...
A for Women 19-30 years 14 mg/day of niacin equivalents 31-50 years 14 mg/day of niacin equivalents 51-70 years 14 mg/day of niacin equivalents > 70 years 14 mg/day of niacin equivalents Pregnancy Method Used to Estimate the Average Requirement There is no direct evidence that would suggest a change in the niacin requirement cluring pregnancy. To derive the EAR for pregnant women, it is estimated that the neeci for niacin increases by 3 mg/day of NEs to cover increased energy utilization and growth in
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From page 136... ...
RI) A for Pregnancy 14-18 years 19-30 years 31-50 years 18 mg/day of niacin equivalents 18 mg/day of niacin equivalents 18 mg/day of niacin equivalents Lactation Method Used to Estimate the Average Requirement An estimated 1.4 mg of preformed niacin is secreted tinily cluring lactation.
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From page 137... ...
As for other B vitamins, extra niacin may be required by persons treated with hemoclialysis or peritoneal dialysis, those with malabsorption syndrome, pregnant women bearing multiple fetuses, and women breastLeecling more than one infant. INTAKE OF NIACIN Food Sources Data obtained from the 1995 Continuing Survey of Food Intakes by Individuals indicate that the greatest contribution to the niacin intake of the U.S.
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From page 138... ...
indicates that this relatively acivantageci group of people over age 60 has a meclian niacin intake of 21 mg/day for men and 17 mg/day for women, again, significantly above the EARs for adult men and women. Intake from Supplements Information from the Boston Nutritional Status Survey on the use of niacin supplements by a free-living elderly population is given in Appendix F
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From page 139... ...
Foods Within the Group that Provide at Least 4 mg of Niacind per Serving Food Group Men Women 4-8 mg > 8 mg Food groups providing at least 5 % of total niacin intake Mixed foodse 14.7 12.4 NAf NA Poultry 10.8 11.9 Turkey light Chicken breast meat, duck, and Cornish and chicken game hen light and dark meat Bread and bread 10.7 11.5 products Ready-to-eat cereals 8.3 10.9 Moderately Highly fortified fortified Mixed foods, main 8.0 7.1 NA NA ingredient is grain Beef 6.5 4.7 Processed meats" 4.7 3.5 Niacin from other food groups Pork 2.8 2.5 Pork and ham Finfish 1.7 2.7 Salmon, Tuna, swordfish, mackerel, sturgeon, and mullet, trout croaker, and Lamb, veal, game 0.4 0.4 Organ meats 0.2 0.3 porgy Lamb, venison, Veal rabbit, and other game Liver a Preformed niacin only, not niacin equivalents. b CSFII = Continuing Survey of Food Intakes by Individuals.
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From page 140... ...
The term flushing covers a burning, tingling, and itching sensation as well as a reddened flush primarily on the face, arms, and chest. Flushing occurs in many patients treateci with nicotinic acid therapeutically.
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From page 141... ...
of nicotinic acid used to treat patients with hypercholesterolemia have procluceci impaired glucose tolerance in otherwise apparently healthy inclivicluals (Miettinen et al., 1969~. The adverse effects on glucose tolerance have been observed cluring short- and long-term administration of the drug (Schwartz, 1993~.
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From page 142... ...
Summary Flushing is the adverse effect first observed after excess niacin intake and is generally observed at lower closes than are other effects. Flushing that results in patients clecicling to change the pattern of niacin intake (i.e., recluce the amount taken at a time or withdraw from treatment)
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From page 143... ...
No data were found to suggest that other life stage groups have increased susceptibility to flushing effects from excess niacin intake. Therefore, the UL of 35 mg/ciay is also set for pregnant and lactating adult women.
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From page 144... ...
Intake Assessment On the basis of ciata from the Third National Health and Nutrition Survey, the highest mean intake of niacin from cliet and supplements for any life stage and gentler group was 39 mg/ciay. This intake was being consumed by men age ci 31 through 50 years, women over age 70, and pregnant women age ci 14 through 55 years.
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From page 145... ...
for children, adolescents, pregnant women, and lactating women are scanty, but evidence suggests that niacin intake in the United States and Canada is generous relative to neeci. Priority should be given to studies in two areas: · the niacin requirement to satisfy nicotinamicle aclenine clinucleoticle (NAD)
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From page 146... ...
1989. Biochemical markers for assessment of niacin status in young men: Levels of erythrocyte niacin coenzymes and plasma tryptophan.
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From page 147... ...
1989. Biochemical markers for assessment of niacin status in young men: Urinary and blood levels of niacin metabolizes.
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From page 148... ...
1997. Effect of niacin status on gastrointestinal function and serum lipids.
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From page 149... ...
. Nitrogen balances, blood pyridine nucleotides, and urinary excretion of N-methylnicotinamide and N-methyl-2-pyridone-5carboxamide on a low-niacin diet.
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