This multicenter, cross-sectional observational study aims to use precision nutrition tools to identify metabolic clusters in adults aged 50-75 years, enabling tailored nutritional and protein recommendations based on specific metabolic characteristics. Conducted at Eurecat-Reus (Catalonia) and AZTI (Bizkaia), the study will enroll 200 participants (75 at Eurecat, 125 at AZTI). Analyses will include metabolomics, gut microbiota profiling, epigenomics, and glycomics, with the goal of refining dietary guidelines and protein intake recommendations to address the specific needs of aging populations.

The study hypothesizes that metabolic characterization using precision nutrition tools in adults aged 50 to 75 will enable the identification of clusters with similar metabolic profiles, thereby enhancing our understanding of each group's nutritional needs and facilitating the development of tailored dietary recommendations, particularly regarding protein intake. This multicenter, cross-sectional observational study will recruit 200 participants, 75 at Eurecat-Reus (Catalonia) and 125 at AZTI (Bizkaia), and will integrate metabolic, clinical, anthropometric, lifestyle, dietary, and microbiota data to form these clusters. The primary objective is to establish metabolic profiles and clusters using precision nutrition tools, while secondary objectives include identifying biomarkers associated with health and aging, assessing the relationship between protein intake and metabolic health, and exploring the associations between gut microbiota composition, glycomic patterns, and metabolic status. Participants will attend two visits: an initial visit for eligibility confirmation and informed consent, followed by a second fasting visit for blood sampling, anthropometric measurements, collection of pre-obtained samples, and the administration of validated questionnaires on lifestyle, dietary intake, and physical activity. Ultimately, the integrated analysis of these data will refine nutritional recommendations to better address the specific metabolic needs of each cluster, thereby improving dietary guidance and overall metabolic health in the aging population.

Inclusion Criteria

• Women or men
• Age: ≥ 50; ≤ 75 years
• BMI: 18.5-35 kg/m² and stable weight for at least 3 months (without weight gain or loss >3 kg).
• Ability to read, write, and speak in Catalan or Spanish.
• Signing of the informed consent form.

Exclusion Criteria

• Age ≤ 49 or ≥ 76 years
• BMI: ≤18.5; ≥ 35
• Pregnant or lactating women
• Presence of chronic or autoimmune disease or metabolic condition that significantly alters nutritional requirements, such as: type I diabetes, celiac disease, inflammatory bowel disease, chronic kidney disease, severe liver disease, uncontrolled thyroid disorders, cancer, food allergies or intolerances, musculoskeletal disorders, moderate or severe cognitive impairment, or immobilization in the last 6 months.
• Alcohol consumption:Men: Consuming 4 or more Standard Drink Units (SDUs)* per day or 28 SDUs per week. Women: Consuming 2 or more Standard Drink Units (SDUs)* per day or 17 SDUs per week.
• Individuals currently participating or who have participated in a clinical trial involving medications or nutritional intervention within the last 30 days before study inclusion.
• Recent use of antibiotics in the last two weeks.

Participants who self-identify as male, female or no-binary are eligible to participate in this study. The study aims to include individuals of various gender identities to ensure diverse representation in the analysis of metabolic and aging biomarkers.

The cohort of the proposed study consists of 200 adults aged 50 to 75 years, who are recruited from two different research centers (Eurecat and AZTI) in Spain.