Supplementing healthy women with up to 5.0 g/d of l-tryptophan has no adverse effects

Chiaki Hiratsuka, Tsutomu Fukuwatari, Mitsue Sano, Kuniaki Saito, Satoshi Sasaki, Katsumi Shibata

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Because of the frequent use of L-tryptophan (L-Trp) in dietary supplements, determination of the no-observed-adverse-effectlevel is desirable for public health purposes. We therefore assessed the no-observed-adverse-effect-level for L-Trp and attempted to identify a surrogate biomarker for excess L-Trp in healthy humans. A randomized, double-blind, placebocontrolled, crossover intervention study was performed in 17 apparently healthy Japanesewomen aged 18-26 ywith a BMI of;20 kg/m2. The participants were randomly assigned to receive placebo (0 g/d) or 1.0, 2.0, 3.0, 4.0, or 5.0 g/d of L-Trp for 21 d each with a 5-wk washout period between trials. Food intake, body weight, general biomarkers in blood and urine, and amino acid composition in blood and urine were not affected by any dose of L-Trp. Administration of up to 5.0 g/d L-Trp had no effect on a profile of mood states category measurement. The urinary excretion of nicotinamide and its catabolites increased in proportion to the ingested amounts of L-Trp, indicating that participants could normally metabolize this amino acid. The urinary excretion of L-tryptophan metabolites, including kynurenine (Kyn), anthranilic acid, kynurenic acid, 3-hydroxykynurenine (3-HK), 3-hydroxyanthranilic acid, and quinolinic acid (QA), all of which are intermediates of the L-Trp/Kyn/QA pathway, was in proportion to L-Trp loading. The response of 3-HK was themost characteristic of these L-Trpmetabolites. This finding suggests that the urinary excretion of 3-HK is a good surrogate biomarker for excess L-Trp ingestion.

Original languageEnglish
Pages (from-to)859-866
Number of pages8
JournalJournal of Nutrition
Volume143
Issue number6
DOIs
Publication statusPublished - 01-06-2013

Fingerprint

Tryptophan
Quinolinic Acid
Kynurenine
Biomarkers
3-Hydroxyanthranilic Acid
Eating
Urine
Kynurenic Acid
Amino Acids
No-Observed-Adverse-Effect Level
Niacinamide
Dietary Supplements
Cross-Over Studies
Public Health
Placebos
Body Weight

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

Hiratsuka, Chiaki ; Fukuwatari, Tsutomu ; Sano, Mitsue ; Saito, Kuniaki ; Sasaki, Satoshi ; Shibata, Katsumi. / Supplementing healthy women with up to 5.0 g/d of l-tryptophan has no adverse effects. In: Journal of Nutrition. 2013 ; Vol. 143, No. 6. pp. 859-866.
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Hiratsuka, C, Fukuwatari, T, Sano, M, Saito, K, Sasaki, S & Shibata, K 2013, 'Supplementing healthy women with up to 5.0 g/d of l-tryptophan has no adverse effects', Journal of Nutrition, vol. 143, no. 6, pp. 859-866. https://doi.org/10.3945/jn.112.173823

Supplementing healthy women with up to 5.0 g/d of l-tryptophan has no adverse effects. / Hiratsuka, Chiaki; Fukuwatari, Tsutomu; Sano, Mitsue; Saito, Kuniaki; Sasaki, Satoshi; Shibata, Katsumi.

In: Journal of Nutrition, Vol. 143, No. 6, 01.06.2013, p. 859-866.

Research output: Contribution to journalArticle

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