Mar Larrosa

Background: Maximal oxygen uptake (VO _2max ) is the gold standard for assessing cardiopulmonary fitness. However, the link between VO _2max and mitochondrial function is complex, with no direct causality proven. Analysing mtDNA copy number offers an innovative way to understand aerobic performance by measuring mitochondrial biogenesis, although its relation to physical performance and fitness is not well studied, especially in trained individuals. Objective: This study aimed to compare VO _2max and mtDNA copy number in blood leukocytes between highly trained runners and nontrained men. It also examined how leukocyte mtDNA content adapts to a 6-week HIIT aerobic training programme in nontrained individuals. Methods: We conducted a cross-sectional study with 20 highly trained runners and 20 nontrained healthy subjects. Then, we implemented a 6-week HIIT training programme for the nontrained group, comparing their VO _2max and mtDNA copy number to a control group. Participants trained 4 min/4 min HIIT treadmill running, three times a week. Results: The cross-sectional part showed that highly trained runners had significantly higher mtDNA copy numbers than nontrained subjects ( p = 0.046; d = 0.652; 95% CI: [0.01, 1.28]; [medium–large effect]); further, we observed a significant positive correlation between mtDNA copy number and VO _2max combining both groups ( p = 0.013; R ² = 0.153 [small–moderate effect]). After the 6-week HIIT programme, the intervention group showed significant increases in both VO _2max ( p < 0.001) and mtDNA copy number ( p = 0.015), with large and medium effect sizes, respectively. The intervention group’s mtDNA copy number increased by 321.6 ± 391.6%; 95% CI: [120.2, 522.9], compared to 12.8 ± 32.8%; 95% CI: [− 5.4, 30.9] in controls, indicating substantial interindividual variability, which could be attributed to a combination of biological factors, but we also observed indications of a potential responder versus non-responder pattern. Conclusion: These findings align with previous research, indicating that mtDNA copy number correlates with VO _2max , being higher in highly trained runners than in nontrained subjects, and increasing with training after a 6-week HIIT intervention. This study is novel in showing that a 6-week HIIT programme significantly boosts leukocyte mtDNA content, enhancing our understanding of individual adaptations to endurance training.

Background: Increasing evidence links gut microbiota composition to neurological disorders, including Alzheimer’s disease (AD), through the gut-brain axis. Microbial metabolites such as lipopolysaccharide (LPS) and butyrate are associated with AD progression. Among modifiable factors, diet plays a central role in shaping gut microbiota and may influence disease-related microbial patterns. Personalized nutrition based on individual microbiota profiles offers a promising strategy to modulate these biomarkers. This protocol describes a study designed to develop a personalized dietary supplement for patients with AD by integrating microbiota, clinical, and dietary data using artificial intelligence (AI) and network analysis. A secondary objective is to assess in a pilot study the short-term effects of the supplement on microbiota composition, function, and plasma metabolomics to identify modifiable biomarkers.Design: This two-phase study will begin with baseline data collection from 60 patients with AD and 60 healthy controls. AI and network-based analyses will identify dietary and microbial variables predictive of disease status. Based on these findings, a personalized supplement will be formulated using dietary components—such as fibers, polyphenols, or fatty acids—targeting microbial taxa and metabolic pathways associated with AD. In the second phase, 60 patients with AD will be randomized (1:1) to receive either the personalized supplement or a standard product for 3 months. Effects on microbial taxa, LPS, short-chain fatty acids (SCFAs), and plasma metabolites will be evaluated before and after the intervention.Methods: Participants will undergo assessments of lifestyle factors, including diet and physical activity, as well as measurements of blood LPS and fecal SCFAs. Machine learning and network analyses will explore links among microbiota, diet, and clinical features. Predictive variables will guide supplement design. The intervention will evaluate changes in LPS, butyrate, and microbial markers. Plasma metabolomic profiles will also be analyzed. Data integration using AI and network approaches will help identify biomarkers and assess intervention outcomes.Discussion: Combining AI and network analysis in microbiota research supports the development of personalized nutrition strategies in AD. This approach may modulate disease-related microbiota and systemic markers, contributing to innovative therapeutic tools and advancing both Alzheimer’s care and nutritional science.Clinical trial registration: ClinicalTrials.gov, identifier NCT06199193.

Background: Mental health issues among young university students have increased in recent years, driven by academic stress and sedentary lifestyles. The YoungFitT Project aims to explore well-being strategies and the psychobiological mechanisms behind their effects on university students. The project includes two studies: the first evaluates the effectiveness of High-Intensity Functional Training (HIFT), Mindfulness-Based Stress Reduction (MBSR), and Qigong (QG) on psychological well-being and cognitive functions, and also explores whether socio-demographic, mental (mindful thinking, sleep quality), physical (physical fitness, physical activity), physiological (heart rate variability), and biological (microbiota) factors mediate or moderate intervention effects on university students. Given that immersive virtual reality (VR) can enhance adherence and provide additional benefits, the second study will explore the feasibility and efficacy of HIFT-VR, MBSR-VR, and QG-VR on university students’ psychological well-being and cognitive functions. Methods: Two mixed-methods randomized controlled trials will be conducted. In Study 1, participants will be randomly assigned to one of three groups (HIFT, MBSR, QG) using a 1:1:1 ratio. Psychological, cognitive, physical, physiological, and biological measures will be evaluated two weeks before and after the interventions. The interventions include three weekly sessions for 12 weeks. Subsequently, a follow-up will be conducted 12 weeks after the intervention to assess psychological well-being. Study 2 is a proof-of-concept study in which VR interventions will be co-designed with input from university students and professionals. Twelve participants from each study will also complete semi-structured interviews to explore their experiences and perceived impact. Discussion: The proposed interventions are expected to produce differential effects on psychological well-being and cognitive function. VR environments may enhance adherence and offer added benefits over conventional training. Findings will inform effective, personalized strategies for the mental and physical health of university youth. Trial registration: www.ClinicalTrials.gov, identifier NCT06406283; Registration date: 2024/05/06.

Chronic inflammatory enteropathies (CIEs) in companion animals represent a group of idiopathic, immune-mediated gastrointestinal disorders in which the intestinal epithelium can be altered, affecting intestinal functionality, nutrient absorption, and microbiota composition. This review presents an overview of markers that could be used for the assessment of intestinal health, focusing extensively on functional biomarkers, with particular attention to fatty acids (including short-chain fatty acids, SCFAs) and amino acids. Studies have consistently shown reduced concentrations of SCFAs in companion animals with CIEs compared to healthy groups. These alterations occur with varying intensity depending on the type of enteropathy. Alterations in saturated, monounsaturated, and long-chain polyunsaturated fatty acids have also been reported in blood and feces, particularly in omega-3 and omega-6 derivatives, as well as in the elongase and desaturase indices responsible for endogenous synthesis. In addition, amino acids serve as precursors to key metabolites involved in mucosal immunity, oxidative stress regulation, and microbial homeostasis. In CIEs, alterations in systemic and fecal amino acid profiles have been observed, reflecting both host metabolic adaptation and microbial dysbiosis. Integrating fatty acid and amino acid profiles can help distinguish different types of enteropathies, providing additional discriminatory power for determining response to dietary treatment. Future research should aim to elucidate the causal relationships between metabolic alterations and disease pathogenesis, which could lead to novel dietary interventions targeting metabolic interactions between the microbiota and the host.

The APOE ε4 allele (APOE4) is a known risk factor for neurodegenerative and cardiovascular diseases, but its link to body composition and metabolism remains debated. The gut microbiota influences host metabolism and immunity, yet its relationship with APOE genotype in healthy individuals is not well understood. The objective of this work was to examine associations between APOE genotype and gut microbiota composition and function in healthy adults, focusing on microbial and metabolic differences related to the APOE4 allele. Seventy-seven healthy Spanish adults were genotyped for APOE. Fecal microbiota profiles were assessed by 16 S rRNA gene sequencing, and predicted functions were inferred using PICRUSt2. Body composition (DEXA) and physical activity (accelerometry) were also measured. APOE4 carriers exhibited subtle shifts in microbiota composition, including a five-fold reduction in Megamonas and lower abundance of the Eubacterium brachy group—both linked to energy harvest and adiposity—compared to APOE3 homozygotes. An uncharacterized Puniceicoccaceae genus was enriched in APOE4 carriers. Although E. brachy group abundance correlated with adiposity, no significant differences in body composition were observed. Functional predictions showed APOE4-associated microbiota enriched in pathways for carotenoid biosynthesis and trehalose metabolism, and depleted in tryptophan biosynthesis, propionate production, and multidrug resistance mechanisms. APOE4 carriers harbor gut microbiota with distinct taxonomic and functional features, potentially reflecting adaptations to metabolic and oxidative challenges. These findings underscore the relevance of the gut microbiome in shaping APOE4-associated phenotypes and warrant further investigation into its mechanistic contributions to health and disease.

The aims of this study were to characterise the faecal amino acid profile of dogs with different chronic digestive diseases (food-responsive enteropathy (FRE), immunosuppressant-responsive enteropathy (IRE)) prior to dietary change, and Giardia infection (GIA), compared to healthy control (HC), and to evaluate their discriminating potential. The HC group presented lower faecal tyrosine (Tyr) and aromatic amino acids (AAAs) compared to FRE or IRE dogs (p = 0.0001). Additionally, the HC group had lower levels of threonine (Thr) (p = 0.0005) than the IRE group, while FRE dogs showed intermediate values. No statistically significant differences in faecal amino acids were observed between FRE and IRE dogs. In contrast, the GIA group had higher faecal amino acid values (except glutamic acid (Glu)) compared to the other dogs. The most determinant variables contributing to the discriminant functions were Tyr, Glu, arginine, and phenylalanine. Validation results of the discriminant functions showed that 44% of stool samples were misclassified, resulting in a 56% success rate. The faecal amino acid profile did not accurately distinguish FRE from IRE dogs; however, faecal excretion of AAs was generally higher in dogs with GIA.