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Metabolomics of the tryptophan-kynurenine degradation pathway and risk of atrial fibrillation and heart failure: potential modification effect of Mediterranean diet.
Razquin, C, Ruiz-Canela, M, Toledo, E, Hernández-Alonso, P, Clish, CB, Guasch-Ferré, M, Li, J, Wittenbecher, C, Dennis, C, Alonso-Gómez, A, et al
The American journal of clinical nutrition. 2021;(5):1646-1654
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Abstract
BACKGROUND The tryptophan-kynurenine pathway is linked to inflammation. We hypothesize that metabolites implicated in this pathway may be associated with the risk of heart failure (HF) or atrial fibrillation (AF) in a population at high risk of cardiovascular disease. OBJECTIVES We aimed to prospectively analyze the associations of kynurenine-related metabolites with the risk of HF and AF and to analyze a potential effect modification by the randomized interventions of the PREDIMED (Prevención con Dieta Mediterránea) trial with Mediterranean diet (MedDiet). METHODS Two case-control studies nested within the PREDIMED trial were designed. We selected 324 incident HF cases and 502 incident AF cases individually matched with ≤3 controls. Conditional logistic regression models were fitted. Interactions with the intervention were tested for each of the baseline plasma metabolites measured by LC-tandem MS. RESULTS Higher baseline kynurenine:tryptophan ratio (OR for 1 SD: 1.20; 95% CI: 1.01, 1.43) and higher levels of kynurenic acid (OR: 1.19; 95% CI: 1.01, 1.40) were associated with HF. Quinolinic acid was associated with AF (OR: 1.15; 95% CI: 1.01, 1.32) and HF (OR: 1.25; 95% CI: 1.04, 1.49). The MedDiet intervention modified the positive associations of kynurenine (Pinteraction = 0.006), kynurenic acid (Pinteraction = 0.008), and quinolinic acid (Pinteraction = 0.033) with HF and the association between kynurenic acid and AF (Pinteraction = 0.02). CONCLUSIONS We found that tryptophan-kynurenine pathway metabolites were prospectively associated with higher HF risk and to a lesser extent with AF risk. Moreover, an effect modification by MedDiet was observed for the association between plasma baseline kynurenine-related metabolites and the risk of HF, showing that the positive association of increased levels of these metabolites and HF was restricted to the control group.
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SLC6A4 polymorphisms modulate the efficacy of a tryptophan-enriched diet on age-related depression and social cognition.
Ugartemendia, L, Bravo, R, Reuter, M, Castaño, MY, Plieger, T, Zamoscik, V, Kirsch, P, Rodríguez, AB
Clinical nutrition (Edinburgh, Scotland). 2021;(4):1487-1494
Abstract
BACKGROUND & AIMS In a placebo controlled study we sought to determine if a four-weeks tryptophan-enriched diet is able to improve age-related depression or social cognitive impairment, depending on polymorphisms located in the promoter region of Solute Carrier Family 6 Member 4 (SLC6A4), also known as serotonin transporter (SERT1) gene. METHODS 91 young volunteers (age: 21 ± 2 yrs) and 127 above 50 years old (58 ± 6 yrs) healthy volunteers completed the study. Participants from the placebo and tryptophan group followed the same protocol. Before starting the study blood samples, to measure serotonin-transporter-linked polymorphic region (5-HTTLPR) and rs25531 polymorphisms, were collected. In addition, before and after completing the study urine samples (to measure 5-hydroxyindolacetic acid (5-HIAA) were taken, while psychological questionnaires (to assess depression and social cognition levels), and a one week dietary record (to calculate the tryptophan (TRP) intake) were assessed. RESULTS The triallelic approach of SLC6A4 showed that in S'S´ subjects there was a positive correlation between TRP intake and 5-HIAA levels. Age of participants, SLC6A4 genotype, and experimental condition were important factors contributing to the outcome of depression and social cognition. CONCLUSIONS 5-HTTLPR and rs25531 polymorphisms play a key role in the response to the TRP- based nutritional intervention, improving only age-related depressive symptoms and empathy in S'S´ subjects who have a higher risk to show signs of depression during their lifetime.
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Effects of intragastric administration of L-tryptophan on the glycaemic response to a nutrient drink in men with type 2 diabetes - impacts on gastric emptying, glucoregulatory hormones and glucose absorption.
Hajishafiee, M, Elovaris, RA, Jones, KL, Heilbronn, LK, Horowitz, M, Poppitt, SD, Feinle-Bisset, C
Nutrition & diabetes. 2021;(1):3
Abstract
BACKGROUND The rate of gastric emptying and glucoregulatory hormones are key determinants of postprandial glycaemia. Intragastric administration of L-tryptophan slows gastric emptying and reduces the glycaemic response to a nutrient drink in lean individuals and those with obesity. We investigated whether tryptophan decreases postprandial glycaemia and slows gastric emptying in type 2 diabetes (T2D). METHODS Twelve men with T2D (age: 63 ± 2 years, HbA1c: 49.7 ± 2.5 mmol/mol, BMI: 30 ± 1 kg/m2) received, on three separate occasions, 3 g ('Trp-3') or 1.5 g ('Trp-1.5') tryptophan, or control (0.9% saline), intragastrically, in randomised, double-blind fashion, 30 min before a mixed-nutrient drink (500 kcal, 74 g carbohydrates), containing 3 g 3-O-methyl-D-glucose (3-OMG) to assess glucose absorption. Venous blood samples were obtained at baseline, after tryptophan, and for 2 h post-drink for measurements of plasma glucose, C-peptide, glucagon and 3-OMG. Gastric emptying of the drink was quantified using two-dimensional ultrasound. RESULTS Tryptophan alone stimulated C-peptide (P = 0.002) and glucagon (P = 0.04), but did not affect fasting glucose. In response to the drink, Trp-3 lowered plasma glucose from t = 15-30 min and from t = 30-45 min compared with control and Trp-1.5, respectively (both P < 0.05), with no differences in peak glucose between treatments. Gastric emptying tended to be slower after Trp-3, but not Trp-1.5, than control (P = 0.06). Plasma C-peptide, glucagon and 3-OMG increased on all days, with no major differences between treatments. CONCLUSIONS In people with T2D, intragastric administration of 3 g tryptophan modestly slows gastric emptying, associated with a delayed rise, but not an overall lowering of, postprandial glucose.
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Use of nutritional supplements based on melatonin, tryptophan and vitamin B6 (Melamil Tripto®) in children with primary chronic headache, with or without sleep disorders: a pilot study.
Bravaccio, C, Terrone, G, Rizzo, R, Gulisano, M, Tosi, M, Curatolo, P, Emberti Gialloreti, L
Minerva pediatrica. 2020;(1):30-36
Abstract
BACKGROUND Headache is one of the main complaints in pediatric neurology. Exogenous melatonin has been shown to be useful and safe in improving sleep-wake cycles and sleep quality in children. Tryptophan as well plays a key role in sleep regulation. So far, no studies tried to analyze the effects of a combination of both melatonin and tryptophan in treating chronic headache in children affected also by night-time awakenings. METHODS Thirty-four children with a diagnosis of chronic headache (with or without sleep disorders) have been enrolled. The study was articulated in two steps: 1) each child was observed for one month without any intervention; 2) children have been then randomized into two groups: the "ME-group", which received the nutritional supplement melatonin for two months and the "MET-group", which received the nutritional supplements melatonin, tryptophan, and vitamin B6 for two months. RESULTS In terms of changes in number of headache events, responders in the ME-group were 91.7% and those in the MET-group were 66.7% (P=0.113). In terms of changes in number of night awakenings, in the ME group, mean number at baseline, after 30 days, and after 60 days were 3.6±3.2, 3.2±3.5, and 2.7±3.4 (P=0.495). In the MET group, mean number of night awakenings was 7.4±8.1, 4.0±4.4, and 3.3±2.9 (P=0.041). CONCLUSIONS Using either nutritional supplement for two months can help in decreasing the monthly number of headache episodes and night awakenings. The addition of tryptophan and vitamin B6 appears to have stronger influence on night awakenings reduction than melatonin only.
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The Effects of a Gluten-Free Diet on Immune Markers and Kynurenic Acid Pathway Metabolites in Patients With Schizophrenia Positive for Antigliadin Antibodies Immunoglobulin G.
Friendshuh, CR, Pocivavsek, A, Demyonovich, H, Rodriguez, KM, Cihakova, D, Talor, MV, Richardson, CM, Vyas, G, Adams, HA, Baratta, AB, et al
Journal of clinical psychopharmacology. 2020;(3):317-319
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Tryptophan catabolites as metabolic markers of vitamin B-6 status evaluated in cohorts of healthy adults and cardiovascular patients.
Ulvik, A, Midttun, Ø, McCann, A, Meyer, K, Tell, G, Nygård, O, Ueland, PM
The American journal of clinical nutrition. 2020;(1):178-186
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Abstract
BACKGROUND Vitamin B-6 status is routinely measured as pyridoxal 5'-phosphate (PLP) in plasma. Low concentrations of PLP are associated with rheumatic, cardiovascular, and neoplastic diseases. We have previously shown that vitamin B-6 status affects the kynurenine (Kyn) pathway of tryptophan (Trp) catabolism. OBJECTIVE This study aimed to comprehensively evaluate the use of Kyns as potential markers of functional vitamin B-6 status across 2 large cohorts. METHODS We measured circulating concentrations of the first 6 metabolites in the Trp catabolic pathway by LC-MS-MS in the community-based Hordaland Health Study (HUSK; n = 7017) and cardiovascular patient-based Western Norway Coronary Angiography Cohort (WECAC; n = 4161). Cross-sectional and longitudinal associations of plasma PLP with Kyns were estimated using linear and nonlinear regression-based methods. RESULTS 3'-Hydroxykynurenine (HK), a substrate, and all 4 products formed directly by the PLP-dependent enzymes kynurenine transaminase and kynureninase contributed to the explanation of circulating PLP in multivariable-adjusted regression models. The construct HK:(kynurenic acid + xanthurenic acid + 3'-hydroxyanthranilic acid + anthranilic acid), termed HK ratio (HKr), was related to plasma PLP with standardized regression coefficients (95% CIs) of -0.47 (-0.49, -0.45) and -0.46 (-0.49, -0.43) in HUSK and WECAC, respectively. Across strata of cohort and sex, HKr was 1.3- to 2.7-fold more sensitive, but also 1.7- to 2.9-fold more specific to changes in PLP than a previously proposed marker, HK:xanthurenic acid. Notably, the association was strongest at PLP concentrations < ∼20 nmol/L, a recognized threshold for vitamin B-6 deficiency. Finally, PLP and HKr demonstrated highly sex-specific and corroborating associations with age. CONCLUSIONS The results demonstrate that by combining 5 metabolites in the Kyn pathway into a simple index, HKr, a sensitive and specific indicator of intracellular vitamin B-6 status is obtained. The data also underscore the merit of evaluating alterations in Kyn metabolism when investigating vitamin B-6 and health.
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The effects of a sleep/recovery supplement: 'Night Time Recharge' on sleep parameters in young adults.
Simper, T, Gilmartin, M, Allwood, D, Taylor, L, Chappell, A
Nutrition and health. 2019;(4):265-274
Abstract
BACKGROUND Concentrated cherry juice reportedly contains melatonin which, in turn, has been highlighted as an important regulator in initiating sleep. AIM: The present investigation aims to clarify whether Night Time Recharge (NTR), a marketed sleep aid containing cherry extract, improves key sleep parameters in young, active adults with mildly poor sleep. METHODS A double-blind, randomized, placebo-controlled, cross-over study design was employed. Twenty participants (nine female) consumed either NTR or a placebo for seven days. Accelerometers were used to assess sleep quality and physical activity levels. Urinary levels of 6-sulphatoxymelatonin (6-SMT), a marker of melatonin synthesis, was assessed via enzyme-linked immunosorbent assay. RESULTS 6-SMT levels increased following NTR treatment (28.95 ng/ml) compared with placebo (4.0 ng/ml) (p < 0.001). There was also a significant difference (p = 0.047) in dietary tryptophan consumption during the NTR treatment (1236 mg) versus placebo (1149 mg). No trace of melatonin was detected from our analysis of the supplement. NTR had no significant effect on any sleep parameters with the exception of sleep latency (p = 0.001). CONCLUSIONS As chemical analysis of NTR by liquid-chromatography mass-spectrometry identified no detectable melatonin, the tryptophan content of the supplement is a likely reason for improvement in sleep latency. These results are in contrast to previous studies which have found a positive effect on sleep following cherry supplementation. Future work should focus on sleep latency and investigating whether cherry juice is effective in participants with problems in initiating sleep.
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Low-grade inflammation and tryptophan-kynurenine pathway activation are associated with adverse cardiac remodeling in primary hyperparathyroidism: the EPATH trial.
Verheyen, N, Meinitzer, A, Grübler, MR, Ablasser, K, Kolesnik, E, Fahrleitner-Pammer, A, Belyavskiy, E, Trummer, C, Schwetz, V, Pieske-Kraigher, E, et al
Clinical chemistry and laboratory medicine. 2017;(7):1034-1042
Abstract
BACKGROUND Primary hyperparathyroidism (pHPT) is associated with low-grade inflammation, left ventricular hypertrophy and increased cardiovascular mortality, but the association between inflammatory markers and parameters of adverse cardiac remodeling is unknown. We investigated the relationship between C-reactive protein (CRP), the essential amino acid tryptophan and its pro-inflammatory derivatives kynurenine and quinolinic acid (QUIN) with echocardiographic parameters. METHODS Cross-sectional baseline data from the "Eplerenone in Primary Hyperparathyroidism" trial were analyzed. Patients with any acute illness were excluded. We assessed associations between CRP, serum levels of tryptophan, kynurenine and QUIN and left ventricular mass index (LVMI), left atrial volume index (LAVI) and E/e'. RESULTS Among 136 subjects with pHPT (79% females), 100 (73%) had arterial hypertension and the prevalence of left ventricular hypertrophy was 52%. Multivariate linear regression analyses with LVMI, LAVI and E/e' as respective dependent variables, and C-reactive protein and tryptophan, kynurenine and QUIN as respective independent variables were performed. Analyses were adjusted for age, sex, blood pressure, parathyroid hormone, calcium and other cardiovascular risk factors. LVMI was independently associated with CRP (adjusted β-coefficient=0.193, p=0.030) and QUIN (β=0.270, p=0.007), but not kynurenine. LAVI was related with CRP (β=0.315, p<0.001), kynurenine (β=0.256, p=0.005) and QUIN (β=0.213, p=0.044). E/e' was related with kynurenine (β=0.221, p=0.022) and QUIN (β=0.292, p=0.006). Tryptophan was not associated with any of the remodeling parameters. [Correction added after online publication (22 April 2017: The sentence "Among 136 subjects with pHPT (79% females), 100 (73%) had left ventricular hypertrophy." was corrected to "Among 136 subjects with pHPT (79% females), 100 (73%) had arterial hypertension and the prevalence of left ventricular hypertrophy was 52%."] Conclusions: Cardiac remodeling is common in pHPT and is associated with low-grade inflammation and activation of the tryptophan-kynurenine pathway. The potential role of kynurenine and QUIN as cardiovascular risk factors may be further investigated in future studies.
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Effect of L-Tryptophan and L-Leucine on Gut Hormone Secretion, Appetite Feelings and Gastric Emptying Rates in Lean and Non-Diabetic Obese Participants: A Randomized, Double-Blind, Parallel-Group Trial.
Meyer-Gerspach, AC, Häfliger, S, Meili, J, Doody, A, Rehfeld, JF, Drewe, J, Beglinger, C, Wölnerhanssen, B
PloS one. 2016;(11):e0166758
Abstract
BACKGROUND/OBJECTIVES Gut hormones such as cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) play a role as satiation factors. Strategies to enhance satiation peptide secretion could provide a therapeutic approach for obesity. Carbohydrates and lipids have been extensively investigated in relation to peptide release. In contrast, the role of proteins or amino acids is less clear. Our aim was to compare the effects of the amino acids L-tryptophan (L-trp) and L-leucine (L-leu) separately on gastric emptying and gut peptide secretion. PARTICIPANTS/METHODS The study was conducted as a randomized (balanced), double-blind, parallel-group trial. A total of 10 lean and 10 non-diabetic obese participants were included. Participants received intragastric loads of L-trp (0.52 g and 1.56 g) and L-leu (1.56 g), dissolved in 300 mL tap water; 75 g glucose and 300 mL tap water served as control treatments. RESULTS Results of the study are: i) L-trp at the higher dose stimulates CCK release (p = 0.0018), and induces a significant retardation in gastric emptying (p = 0.0033); ii) L-trp at the higher dose induced a small increase in GLP-1 secretion (p = 0.0257); iii) neither of the amino acids modulated subjective appetite feelings; and iv) the two amino acids did not alter insulin or glucose concentrations. CONCLUSIONS L-trp is a luminal regulator of CCK release with effects on gastric emptying, an effect that could be mediated by CCK. L-trp's effect on GLP-1 secretion is only minor. At the doses given, the two amino acids did not affect subjective appetite feelings. TRIAL REGISTRATION ClinicalTrials.gov NCT02563847.
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Valence-dependent influence of serotonin depletion on model-based choice strategy.
Worbe, Y, Palminteri, S, Savulich, G, Daw, ND, Fernandez-Egea, E, Robbins, TW, Voon, V
Molecular psychiatry. 2016;(5):624-9
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Abstract
Human decision-making arises from both reflective and reflexive mechanisms, which underpin goal-directed and habitual behavioural control. Computationally, these two systems of behavioural control have been described by different learning algorithms, model-based and model-free learning, respectively. Here, we investigated the effect of diminished serotonin (5-hydroxytryptamine) neurotransmission using dietary tryptophan depletion (TD) in healthy volunteers on the performance of a two-stage decision-making task, which allows discrimination between model-free and model-based behavioural strategies. A novel version of the task was used, which not only examined choice balance for monetary reward but also for punishment (monetary loss). TD impaired goal-directed (model-based) behaviour in the reward condition, but promoted it under punishment. This effect on appetitive and aversive goal-directed behaviour is likely mediated by alteration of the average reward representation produced by TD, which is consistent with previous studies. Overall, the major implication of this study is that serotonin differentially affects goal-directed learning as a function of affective valence. These findings are relevant for a further understanding of psychiatric disorders associated with breakdown of goal-directed behavioural control such as obsessive-compulsive disorders or addictions.