Plasma Taurine in Older Women With Obesity: Impact of Metabolic Phenotype and Combined Exercise

Plasma Taurine Concentrations in Older Women With Obesity: The Influence of Metabolic Phenotype and Combined Exercise Training

Population aging has been accompanied by a rise in obesity and other chronic diseases, increasing cardiovascular risk particularly among women, who exhibit a higher prevalence in older age groups compared to men. Aging and obesity share pathophysiological mechanisms, such as chronic inflammation and oxidative stress. However, distinct obesity phenotypes exist, such as metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). Consequently, therapeutic interventions involving nutritional strategies and physical training are highly relevant, especially for older women. Taurine, a sulfur-containing amino acid, plays a role in modulating oxidative stress, inflammation, osmoregulation, and mitochondrial function. Rationale: Plasma taurine concentrations are lower in women with obesity compared to healthy individuals. However, studies investigating these concentrations across different phenotypes-particularly in older women, a group susceptible to functional and metabolic changes-remain limited. Understanding these variations could clarify taurine's role in the pathophysiology of obesity and aging and inform personalized therapeutic strategies. Combined physical training stands out as an effective strategy for modulating inflammatory, oxidative, and metabolic pathways, in addition to improving psychosocial aspects. Given that taurine levels can be influenced by these pathways, investigating the taurine response to physical training across different metabolic phenotypes may contribute to developing low-cost interventions aimed at improving the quality of life for older women with obesity.

This study aims to investigate differences in plasma taurine concentrations between older women with MHO and MUO, and to evaluate the response of taurine-as well as metabolic, inflammatory, oxidative, and cellular markers-to a 16-week combined physical training intervention. The study will involve 36 older women with obesity, classified as having either MHO or MUO. In Stage 1, nutritional and anthropometric assessments will be conducted, along with the collection of biological samples for biochemical and molecular analyses. In Stage 2, participants will undergo a combined physical exercise intervention for 16 weeks; nutritional, anthropometric, physical performance, and functional assessments will be performed, as well as the collection of biological samples for pre- and post-intervention biochemical and molecular analyses. Stage 3 will consist of integrated data analysis to identify variables predicting plasma taurine concentrations at baseline and post-intervention. Data analysis method: Data will be analyzed using Student's t-tests or Mann-Whitney tests (Stage 1), ANOVA or Kruskal-Wallis tests (Stage 2), Pearson or Spearman correlations (Stages 1 and 2), and linear regression models (Stage 3), using SPSS software (α=5%). Expected results: It is expected that older women with OMS will exhibit higher baseline taurine concentrations and that combined physical training will increase these concentrations in both groups-with a more pronounced effect in the OMS phenotype-in addition to promoting cardiometabolic, functional, inflammatory, oxidative, and psychosocial benefits.

Inclusion Criteria

• Women aged 60 to 75 years.
• Residents of the city or region of Ribeirão Preto, São Paulo, Brazil.
• Physically inactive for at least 3 months.
• Body mass index (BMI) ≥ 30 kg/m² (PAHO, 2002).
• Body fat percentage ≥ 35%, according to obesity diagnostic criteria (Batsis et al., 2016; Rubino et al., 2025).

Classified into one of two obesity phenotypes based on Zembic et al. (2021):

Metabolically Healthy Obesity (MHO/OMS): all of the following criteria must be met:

• Systolic blood pressure (SBP) < 130 mmHg;
• Waist-to-hip ratio < 0.95;
• Fasting blood glucose < 126 mg/dL.

Metabolically Unhealthy Obesity (MUO/OMNS): meets two or fewer of the above criteria.

Exclusion Criteria

Clinical conditions

• Contraindication to physical exercise.

• Current or previous diagnosis of:

  • Neoplasms;
  • Autoimmune diseases;
  • Hepatic diseases;
  • Coronary diseases;
  • Renal diseases;
  • Neurodegenerative diseases;
  • Infectious diseases.

Previous or ongoing treatments

• Use of medication for thyroid disorders.
• Participation in exercise training programs, nutritional counseling, or weight loss treatment within the 3 months preceding the intervention.

Lifestyle habits

• Current smoking.
• Alcohol consumption.

For MHO Group:

• Medication use

  • Hypoglycemic agents
  • Insulin (Bell, Kivimäki, & Hamer, 2014).

• Protocol adherence *Attendance at less than 80% of the training sessions (De Carvalho et al., 2021).