Tryptophan-Niacin Relationships in Pregnancy

Wertz, Anne W.; Lojkin, Mary E.; Bouchard, Beryl S.; Derby, Marilyn B.

doi:10.1093/jn/64.3.339

Cited by 47 publications

(11 citation statements)

References 17 publications

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“…dence that This suggests that the increased efficiency of conrespect to version found in pregnancy is not due to pyridoxdata sug-ine deficiency as such, but is probably related to se activity the endocrine changes associated with pregnancy. hormonal Similar results were reported by Wertz, Lojkin, te of pyri-Bouchard and Derby (34), who found that pregnant subjects excreted increased levels of niacin of kynure-metabolites. Various reports in the literature have renic acid indicated the influence of endocrine organs on onding in-tryptophan metabolism.…”

Section: Discussionsupporting

confidence: 89%

The Effect of Vitamin Supplementation on the Urinary Excretion of Tryptophan Metabolites by Pregnant Women*

Brown¹,

Thornton²,

Price³

1961

J. Clin. Invest.

110

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Section: Discussionsupporting

confidence: 89%

The Effect of Vitamin Supplementation on the Urinary Excretion of Tryptophan Metabolites by Pregnant Women*

Brown¹,

Thornton²,

Price³

1961

J. Clin. Invest.

110

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“…Inter-individual differences (about 30 %) in the conversion efficiency of tryptophan to niacin have been reported (Patterson et al, 1980;Horwitt et al, 1981). The conversion of tryptophan to niacin is more efficient in pregnant women than in other adults (Wertz et al, 1958); this is supported by data collected during pregnancy in animals (Ftukijwatari et al, 2004). However, the tryptophan to niacin conversion ratio would need to be confirmed by other studies in pregnant women.…”

Section: Transport In Blood and Distribution To Tissuesmentioning

confidence: 90%

“…UK COMA (DH, 1991) concluded that it was unnecessary to increase niacin intake during pregnancy as the additional requirement would be met by changes in the metabolism of tryptophan (Wertz et al, 1958). Based on a preformed niacin concentration of 2.7 mg/L in mature human milk, UK COMA recommended an increment of 2.3 mg NE/day in addition to the PRI for non-pregnant women.…”

Section: Pregnancy and Lactationmentioning

confidence: 99%

Scientific Opinion on Dietary Reference Values for niacin

Products¹

2014

EFSA Journal

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Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for niacin. Niacin is a generic term for nicotinic acid and nicotinamide. Niacin can be synthesised in the human body from the indispensable amino acid tryptophan. Approximately 60 mg of tryptophan yields 1 mg of niacin defined as 1 mg niacin equivalent (NE). Long-term inadequate intake of tryptophan and niacin can lead to the development of pellagra. In the absence of new scientific data, the Panel endorses the Average Requirement (AR) for adults of 1.3 mg NE/MJ (5.5 mg NE/1 000 kcal) adopted by the Scientific Committee for Food (1993), based on data on urinary excretion of niacin metabolites as an endpoint. The Population Reference Intake (PRI) of 1.6 mg NE/MJ (6.6 mg NE/1 000 kcal) is derived from the AR assuming a coefficient of variation of 10 %. For infants aged 7-11 months, children and adolescents, as well as for pregnant and lactating women, the Panel considers that there is no evidence that the relationship between niacin requirement and energy requirement differs from that of adults; therefore, the AR and PRI for adults are also applied to these age and life stage groups. Niacin is a generic term for nicotinic acid and nicotinamide, soluble organic compounds that belong to the group of B vitamins. Niacin is found in a wide range of foods. Main food groups contributing to niacin intakes of adults include meat and meat products, grains and grain-based products and milk and milk products. Depending on the foodstuff, the mean absorption of niacin is from about 23 % to about 70 %; it is lowest from cereals and highest from animal products. Niacin can be synthesised in the human body from the indispensable amino acid tryptophan. Approximately 60 mg of tryptophan yields 1 mg of niacin defined as 1 mg niacin equivalent (NE). Inadequate iron, riboflavin or vitamin B6 status decreases the conversion of tryptophan to niacin.In vivo nicotinic acid is converted to nicotinamide, which is a precursor for nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which are essential to cells and involved in many biochemical reactions. Niacin circulates in the plasma as nicotinamide and nicotinic acid. Both forms are transported to cells and tissues, which they enter by diffusion to perform the intracellular functions of niacin. Niacin is trapped within the cell as NAD or NADP.The major pathway of catabolism of nicotinic acid and nicotinamide is by methylation in the liver to N-methyl-nicotinamide (NMN) and subsequent oxidation to N-methyl-2-pyridone-carboxamide (2-Pyr) and N-methyl-4-pyridone-carboxamide (4-Pyr). In humans, the two major excretion products are NMN and 2-Pyr, which under normal conditions represent about 20-35 % and 45-60 % of niacin metabolites, respectively. The amount of niacin metabolites excreted depends on the niacin and tryptophan intake. Long-term inadequate intake of tryptophan and niacin results in...

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“…Price et al in 1967, 12) Toseland and Price in 1969, 13) and Luhby et al 14) in 1971 reported a similar finding. On the contrary, Wertz et al 15) and Lojkin 16) reported that the urinary excretion of N 1 -methylnicotinamide (MNA) was higher in pregnant women and rats than in non-pregnant women and rats. We also clarified that the conversion of L-Trp to Nam was higher in the pregnant state than in nonpregnant state in women and female rats.…”

mentioning

confidence: 99%

Urine 3-hydroxykynurenine is higher during the postovulatory phase than in the preovulatory phase indicating a higher vitamin B6 requirement

Shibata

2014

Bioscience, Biotechnology, and Biochemistry

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The relationship between l-tryptophan to nicotinamide metabolism and the menstrual cycle of Japanese women was investigated. Nine metabolism intermediates from urine samples collected during the preovulatory and postovulatory phases were measured. Only urine 3-hydroxykynurenine was higher in the postovulatory phase than in the preovulatory phase. This increase in 3-hydroxykynurenine suggests a decreased reaction of 3-hydroxykynurenine → 3-hydroxyanthranilic acid catalyzed by kynureninase, a vitamin B6 enzyme.

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Tryptophan-Niacin Relationships in Pregnancy

Cited by 47 publications

References 17 publications

The Effect of Vitamin Supplementation on the Urinary Excretion of Tryptophan Metabolites by Pregnant Women*

The Effect of Vitamin Supplementation on the Urinary Excretion of Tryptophan Metabolites by Pregnant Women*

Scientific Opinion on Dietary Reference Values for niacin

Urine 3-hydroxykynurenine is higher during the postovulatory phase than in the preovulatory phase indicating a higher vitamin B6 requirement

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