Stable isotope ratios of nitrogen and carbon as biomarkers of a vegan diet

Urbanization's hidden influence: Linking landscape alterations and feather coloration with pigeon's cholesterol levels

Urbanization significantly impacts synanthropic birds, influencing their physiology and appearance. For instance, urban environments are associated with higher plasma cholesterol levels in birds due to human-derived food sources. Additionally, landscape changes create environmental pressures, which favor more melanic plumages. Current evidence suggests that urbanization may influence bird cholesterol through mechanisms beyond diet, possibly via the pleiotropic effects of the melanocortin system. In this study, we examine how cholesterolemia varies in urban pigeons (Columba livia), a species with polymorphic plumage, across different levels of urbanization and degrees of melanism. To investigate this, we analyzed pigeons along urbanization gradients and sampled birds from various locations in Santiago, a South American metropolis. Plumage color was characterized using image analysis, and the expression of the MITF and MC1R genes in the skin was measured. Blood samples were analyzed for biochemical parameters, genetic sex determination, and nitrogen isotopic signatures (δ15N) in red blood cells. We found correlations between human-induced spatial heterogeneity indexes (e.g., Impervious Surface, Global Human Modification, and Land Surface Temperature) and plumage melanism. However, no direct relationship was found between these landscape features and cholesterol levels, although there were links to glucose and triglycerides. Interestingly, plasma cholesterol levels strongly correlated with plumage melanism features independent of δ15N, suggesting a non-trophic origin of elevated cholesterol. Furthermore, we identified and quantified the indirect effects of urbanization on cholesterolemia using structural equation modeling. This evidence highlights the interplay between urban stressors and bird melanism, underscoring the importance of pleiotropic phenomena in socio-eco-evolutionary dynamics of urban ecosystems.

Increasing plant protein in the diet induces changes in the plasma metabolome that may be beneficial for metabolic health. A randomized crossover study in males

BACKGROUND & AIM

Dietary shifts replacing animal protein (AP) with plant protein (PP) sources have been associated with lowering cardiometabolic risk (CMR), but underlying mechanisms are poorly characterized. This nutritional intervention aims to characterize the metabolic changes induced by diets containing different proportions of AP and PP sources in males at CMR.

DESIGN

This study is a 4-week, crossover, randomized, controlled-feeding trial in which 19 males with CMR followed two diets providing either 36 % for the control diet (CON-D) or 64 % for the flexitarian diet (FLEX-D) of total protein intake from PP sources. Plasma nontargeted metabolomes (LC-MS method) were measured in the fasted state and after a high-fat challenge meal at the end of each intervention arm. Lipogenesis and protein synthesis fluxes, flow-mediated dilatation (FMD) and gluco-lipidic responses were assessed after the challenge meal. Data were analyzed with mixed models, and univariate and multivariate models for metabolomics data.

RESULTS

In both arms CMR improved with time, with decreased body weight (-0.9 %), insulin resistant (-34 %, HOMA-IR, Homeostatic Model Assessment for Insulin Resistance) and low-density lipoproteins (LDL)-cholesterol (-11 %). Diet had no effect on FMD or metabolic fluxes, but a trend (0.05

CONCLUSIONS

Despite little changes in risk factors after 4 wk, this study evidenced subtle metabolic adaptations in amino acids and lipid metabolism and gut microbiota activity occurring after higher PP source intake that may be beneficial to CMR.

CLINICALTRIALS

GOV STUDY IDENTIFIER

NCT04236518.

CLINICAL TRIAL REGISTRY

NCT04236518 on ClinicalTrials.gov.

Collapse

Key Words

• Branched-chain amino acids
• Hypertriglyceridemic waist phenotype
• Plant proteins
• Plant-based diet
• Postprandial response
• Trimethylamine-oxide

Collapse

MESH Headings

• Adult
• Humans
• Male
• Middle Aged
• Young Adult
• Blood Glucose/metabolism
• Cardiometabolic Risk Factors
• Cross-Over Studies
• Fasting/blood
• Insulin Resistance
• Metabolome/physiology
• Postprandial Period/physiology
• Plant Proteins, Dietary/administration & dosage

Collapse

Grants Collapse

Affiliation(s)

Gaïa Lépine Université Clermont Auvergne, INRAE, UNH, 63000, Clermont-Ferrand, France; Université Paris-Saclay, AgroParisTech, INRAE, UMR PNCA, 91120, Palaiseau, France
François Mariotti Université Paris-Saclay, AgroParisTech, INRAE, UMR PNCA, 91120, Palaiseau, France
Marie Tremblay-Franco Toxalim - Research Centre in Food Toxicology, Toulouse University, INRAE, ENVT, INP-Purpan, UT3, F-31300, Toulouse, France; MetaboHUB-MetaToul, National Infrastructure of Metabolomics and Fluxomics, Toulouse, 31077, France
Marion Courrent CHU Clermont-Ferrand, Inserm CIC 1405, France
Marie-Anne Verny Université Clermont Auvergne, INRAE, UNH, 63000, Clermont-Ferrand, France
Jérémie David Université Clermont Auvergne, INRAE, UNH, 63000, Clermont-Ferrand, France
Véronique Mathé Université Paris-Saclay, AgroParisTech, INRAE, UMR PNCA, 91120, Palaiseau, France
Patrick Jame Universite Claude Bernard Lyon 1, CNRS, ISA, UMR5280, 5 rue de la Doua, F-69100 Villeurbanne, France
Anthony Anchisi Universite Claude Bernard Lyon 1, CNRS, ISA, UMR5280, 5 rue de la Doua, F-69100 Villeurbanne, France
Catherine Lefranc-Millot Roquette Frères, Lestrem, France
Caroline Perreau Roquette Frères, Lestrem, France
Laetitia Guérin-Deremaux Roquette Frères, Lestrem, France
Céline Chollet CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), MetaboHUB, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
Florence Castelli CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), MetaboHUB, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
Emeline Chu-Van CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), MetaboHUB, Université Paris-Saclay, 91191 Gif-sur-Yvette, France
Jean-François Huneau Université Paris-Saclay, AgroParisTech, INRAE, UMR PNCA, 91120, Palaiseau, France
Didier Rémond Université Clermont Auvergne, INRAE, UNH, 63000, Clermont-Ferrand, France
Gisèle Pickering CHU Clermont-Ferrand, Inserm CIC 1405, France
Hélène Fouillet Université Paris-Saclay, AgroParisTech, INRAE, UMR PNCA, 91120, Palaiseau, France.
Sergio Polakof Université Clermont Auvergne, INRAE, UNH, 63000, Clermont-Ferrand, France.

Collapse

Changes in urinary stable nitrogen isotope ratios during controlled short-term energy deficit: a proof-of-principle analysis

PURPOSE

Stable isotope ratios of nitrogen (δ15N) have previously been shown to increase in human hair during periods of catabolism. The goal of this study was to assess changes in δ15N in urinary urea (δ15Nurea) and Δ15N during a short-term controlled energy deficit.

METHODS

We analyzed samples from 6 recreationally active men (25 ± 1 years, BMI: 23.5 ± 0.6 kg/m2) who participated in a repeated measures cross-over study involving 4 days of energy deficit (ED, ~ 15 kcal/kg FFM) without and with exercise (ED-EX, ED + EX) and control conditions in energy balance (CON-EX, CON + EX). δ15Nurea was analyzed from urine samples, and Δ15N was calculated as δ15Nurea-δ15Ndiet, with δ15Ndiet obtained from diet prescriptions.

RESULTS

δ15Nurea was significantly elevated in ED-EX (4.4 ± 0.2‰) when compared to CON-EX (3.7 ± 0.1‰; p = 0.026) and CON + EX (3.34 ± 0.13‰, p = 0.001). As a consequence, Δ15N was positive in ED-EX (0.2 ± 0.2‰) and remained negative in ED + EX (- 0.6 ± 0.5‰), CON-EX (- 1.0 ± 0.2) and CON + EX (- 1.1 ± 0.2). Differences in Δ15N were significant between ED-EX and CON-EX (p = 0.005) and ED-EX and CON + EX (p = 0.006).

CONCLUSION

Our results suggest that δ15Nurea and subsequently Δ15N are responsive to a short-term energy deficit, likely due to increased amino acid oxidation to meet energy demands and preferable elimination of 14N.

Elimination of 15N-thymidine after oral administration in human infants

BACKGROUND

We have developed a new clinical research approach for the quantification of cellular proliferation in human infants to address unanswered questions about tissue renewal and regeneration. The approach consists of oral 15N-thymidine administration to label cells in S-phase, followed by Multi-isotope Imaging Mass Spectrometry for detection of the incorporated label in cell nuclei. To establish the approach, we performed an observational study to examine uptake and elimination of 15N-thymidine. We compared at-home label administration with in-hospital administration in infants with tetralogy of Fallot, a form of congenital heart disease, and infants with heart failure.

METHODS

We examined urine samples from 18 infants who received 15N-thymidine (50 mg/kg body weight) by mouth for five consecutive days. We used Isotope Ratio Mass Spectrometry to determine enrichment of 15N relative to 14N (%) in urine.

RESULTS/FINDINGS

15N-thymidine dose administration produced periodic rises of 15N enrichment in urine. Infants with tetralogy of Fallot had a 3.2-fold increase and infants with heart failure had a 4.3-fold increase in mean peak 15N enrichment over baseline. The mean 15N enrichment was not statistically different between the two patient populations (p = 0.103). The time to peak 15N enrichment in tetralogy of Fallot infants was 6.3 ± 1 hr and in infants with heart failure 7.5 ± 2 hr (mean ± SEM). The duration of significant 15N enrichment after a dose was 18.5 ± 1.7 hr in tetralogy of Fallot and in heart failure 18.2 ± 1.8 hr (mean ± SEM). The time to peak enrichment and duration of enrichment were also not statistically different (p = 0.617 and p = 0.887).

CONCLUSIONS

The presented results support two conclusions of significance for future applications: (1) Demonstration that 15N-thymidine label administration at home is equivalent to in-hospital administration. (2) Two different types of heart disease show no differences in 15N-thymidine absorption and elimination. This enables the comparative analysis of cellular proliferation between different types of heart disease.