Fibromyalgia (FM) is a disorder characterized by widespread chronic pain, significant depression, and various neural abnormalities. Recent research suggests a reciprocal exacerbation mechanism between chronic pain and depression. In patients with FM, dysregulation of tryptophan (Trp) metabolism has been identified. Trp, an essential amino acid, serves as a precursor to serotonin (5-HT), a neuromodulator that influences mood, appetite, sleep, and pain perception through the receptors 5-HT1, 5-HT2, and 5-HT3. Additionally, Trp is involved in the kynurenine pathway, a critical route in the immune response, inflammation, and production of neuroactive substances and nicotinamide adenine dinucleotide (NAD+). The activation of this pathway by pro-inflammatory cytokines, such as tumor necrosis factor α (TNF-α) and interferon gamma (IFN-γ), leads to the production of kynurenic acid (KYNA), which has neuroprotective properties, and quinolinic acid (QA), which is neurotoxic. These findings underscore the crucial balance between Trp metabolism, 5-HT, and kynurenine, where an imbalance can contribute to the dual burden of pain and depression in patients with FM. This review proposes a novel therapeutic approach for FM pain management, focusing on inhibiting QA synthesis while co-administering selective serotonin reuptake inhibitors to potentially increase KYNA levels, thus dampening pain perception and improving patient outcomes.

The role of the gut microbiota in obesity has been extensively studied worldwide, but research in Mexican populations is still limited. This is particularly important given the high obesity rates in Mexico, despite a traditional diet rich in diverse, plant-based foods. We conducted a systematic review of studies examining the gut microbiota in obese Mexican children and adults. The literature search was conducted in the Medline, CINAHL, SciELO, Redalyc and Web of Science databases. The included studies addressed topics such as obesity in different Mexican subgroups (e.g., adults, children, rural communities), dietary behaviors and interventions, traditional dietary patterns, and gut microbiota composition. Of the 2332 datasets, 19 studies met the inclusion criteria. These studies indicated that obesity in Mexican individuals is associated with specific changes in the gut microbiota, including decreased bacterial diversity and shifts in the abundance of key microbial genera. Differences were found between age groups and regions. This review highlights a clear association between gut microbiota composition and obesity in the Mexican population. Further research is essential to investigate how the traditional Mexican diet may influence gut health and serve as a potential tool to treat obesity.

While the gut microbiota of obese children in Mexico has been studied, its relationship with depressive and anxiety symptoms in obese adults remains unexplored. The aim of this study was to describe the gut microbiota profile of Mexican adults with obesity and its association with depression and anxiety. We sequenced the V3-V4 region of the 16S rRNA gene from stool samples of obese adults categorized into four groups: control (OCG), with depressive symptoms (OD), with anxiety symptoms (OAx), or with both (ODAx). Alpha diversity was assessed using t-tests, beta diversity was assessed with PERMANOVA, and taxonomic differences was assessed with LEfSe. Associations between bacterial genera and clinical variables were analyzed using the Maaslin2 library. Bacteroidota was the most prevalent phylum, and Prevotella was the dominant enterotype across all groups. Although overall diversity did not differ significantly, 30 distinct taxonomic biomarkers were identified among groups as follows: 4 in OCG (Firmicutes), 5 in OD (Firmicutes, Bacteroidota), 13 in OAx (Firmicutes, Bacteroidetes, Fusobacteroidota, Proteobacteria), and 8 in ODAx (Firmicutes). This is the first study to identify distinct gut microbiota profiles in obese Mexican adults with depressive and anxiety symptoms. These findings suggest important microbial biomarkers for improving the diagnosis and treatment of mental health conditions in obesity.

Background: Obesity and mental disorders are associated with gut microbiota dysbiosis and gut–brain axis dysfunction. This secondary analysis evaluated the effects of a 12-week weight loss program (WLP) based on a hypocaloric traditional Mexican diet (TMD) and moderate-intensity exercise on gut microbiota, body composition (BC), and metabolic parameters in Mexican adults with obesity with and without depression and anxiety symptoms. Methods: A total of 106 adults with obesity were classified based on the presence or absence of depressive and anxiety symptoms into an obesity control group without symptoms (OCG), improved symptoms (OIS), and persistent symptoms (OPS). Stool samples were analyzed by sequencing the V3–V4 region of the 16S rRNA gene. Longitudinal changes in serum biochemistry, BC, intestinal permeability markers, and gut microbiota were analyzed using linear mixed-effects models. Differential taxa were identified using linear discriminant analysis effect size (LEfSe), and associations between bacterial genera, biochemical variables, and dietary components were explored using MaAsLin 2. Results: The WLP significantly improved metabolic, inflammatory, intestinal permeability, and BC markers, as well as depressive and anxiety symptoms, although participants remained in WHO grade I obesity. These improvements were accompanied by selective, group-dependent modulation of bacterial genera rather than broad microbiota restructuring. LEfSe identified 22 taxonomic biomarkers: 16 in OPS, 5 in OIS, and 1 in OCG. Conclusions: The culturally adapted WLP, which combined a hypocaloric TMD with exercise, promoted improvements in metabolism and BC in all participants, along with group-specific gut microbiota remodeling that may be associated with differential changes in depressive and anxiety symptoms in the context of persistent obesity.

Background: Obesity is characterized by chronic low-grade inflammation and metabolic disturbances, including an altered tryptophan (Trp) catabolism through the kynurenine pathway (KP). Since the KP is closely linked to immune activity, energy metabolism, and hepatic function, modulating its flux through lifestyle interventions has gained interest as a potential therapeutic strategy. Objective: This exploratory study aimed to investigate the impact of a structured 12-week weight loss program (WLP) on serum KP metabolites in a sample of Mexican women with obesity. Methods: This study involved a pre–post-intervention design conducted in twenty-four women with clinically diagnosed obesity from the Mexican Navy who underwent a structured 12-week weight loss program combining a hypocaloric diet with moderate-intensity aerobic exercise; no control group was included. Anthropometric parameters, serum biochemistry, and circulating levels of Trp, kynurenine (KYN), kynurenic acid (KYNA), and 3-hydroxykynurenine (3-HK) were assessed before and after intervention. Psychological assessments of anxiety and depression were also conducted in a subset of participants. Results: The WLP significantly reduced body weight, BMI, fat mass, fasting insulin, and C-reactive protein levels. Serum concentrations of Trp, KYN, and KYNA decreased, while 3-HK showed a non-significant upward trend. Enzymatic indexes revealed a significant increase in the 3-HK/KYN ratio and a decrease in the KYNA/3-HK ratio, suggesting a shift toward kynurenine monooxygenase (KMO) branch. Notably, higher KYNA-related ratios were inversely associated with depressive symptoms. Conclusions: These findings position the KP as a responsive metabolic interface potentially linking improvements in body composition, liver function, and psychological status during structured weight loss efforts.