Plant-based Diets and Healthy Aging (TCAS)

Plant-based Diets and Healthy Aging - the Tzu Chi Aging Study (TCAS)

This prospective study investigates the health effects of vegetarian and plant-based diets in middle-aged and older adults in Taiwan, specifically, recruiting 5000 Tzu Chi volunteers. Previous Tzu Chi cohorts found vegetarian diets were protectively associated with incidences of diabetes, stroke, gout, cataracts, insomnia, and gallstones, while reducing healthcare costs. The study also aims to clarify dietary patterns-particularly plant-based and vegetarian diets-and determine how potential deficiencies or excesses of various nutrients influence common aging-related health issues, including healthy cognitive decline, sarcopenia, and the risk of age-related diseases, in order to inform dietary and lifestyle recommendations that promote healthy aging and maintain physical function.

Study Overview

• Status: Recruiting
• Conditions: Frailty; Sarcopenia; Healthy Aging; Cognitive Decline

Detailed Description

This study establishes a new cohort to investigate the role of vegetarian and plant-based diets in healthy aging, integrating functional, nutritional, and genetic data. The primary objective is to clarify how dietary patterns and nutrient intake influence aging-related health conditions, including sarcopenia, cognitive function, physical function, and psychological well-being, and investigate how the associations between diet and these health conditions may be modified by genetic risk factors.

Participants are Tzu Chi volunteers aged 40 years and older who undergo comprehensive health evaluations at Dalin Tzu Chi Hospital every three years. This population consists of a uniquely high proportion of vegetarians, non-smoking non-alcohol drinking individuals, and older adults who are active in communities and social engagement and community services; providing a unique opportunity to examine the role of plant-based diets and community services on aging related conditions without confounding by smoking and alcohol. Diet data are collected through a previously validated food frequency questionnaire, a short newly developed questionnaire - Taiwan Diet Quality Calculator - that will be validated within a subcohort of the current study, and food diaries for participants who are willing to provide such details. Nutritional biomarkers (e.g., serum vitamin B12, vitamin D, skin carotenoids), along with routine health examination values (complete blood counts, lipid profiles, renal and liver functions, bone mineral density) will also be collected. When funding permits, genome-wide genotyping, metabolomics, and other aging-related biomarkers will also be examined.

For cohort follow-up, study participants will be invited back for follow-up health examination every three years. In addition, data will also be linked to National Health Insurance Claim database, National Cancer registry, and National Mortality Registry in Taiwan to further ascertain relevant health outcomes.

By integrating comprehensive dietary assessments, nutritional biomarkers, health examination and genetic data, and aging-related functional outcomes, this cohort will provide an unique opportunity to examine dietary patterns, nutrient requirements, and lifestyle that best support healthy aging. The inclusion of genomic and metabolomic analyses will further enable the investigation of diet-gene interactions, supporting the development of precision nutrition strategies for individuals at elevated genetic risk. This research is expected to inform strategies for disease prevention and the maintenance of functional independence in older adults.

• Study Type: Observational
• Enrollment (Estimated): 5000

Contacts and Locations

• Study Contact: Name: Hsueh-Ting Chiu, PhD; Phone Number: 27 +886-5-6325080; Email: tinachiu@nhri.edu.tw
• Study Contact Backup: Name: Wen-Ling Lin, PhD; Phone Number: 29 +886-5-6325080; Email: wenling926@nhri.edu.tw

Study Locations

• Taiwan
  • Chiayi
    • Dalin, Chiayi, Taiwan, 622
      • Recruiting
      • Dalin Tzu Chi Hospital.
      • Contact: Hsueh-Ting Chiu, phd; Phone Number: +886-5-6325080#27; Email: tinachiu@nhri.edu.tw

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Middle-aged and older adults (≥40 years) who are volunteers of the Tzu Chi Foundation or their relatives and friends, participating in the 2-day comprehensive health examination program in Taiwan.

Description

Inclusion Criteria:

• Age 40 years or older.
• Volunteers of the Tzu Chi Foundation.
• Participating in the 2-day comprehensive health examination program.

Exclusion Criteria:

• Pregnant individual.
• Diagnosed with dementia or poor cognition resulting in inability to answer questionnaires.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cognitive Function	Cognitive function will be assessed using Montreal Cognitive Assessment [MoCA], Taiwanese version. (Score range 0-30, unit = points). A score ≥26 is generally considered normal, while scores <26 suggest possible cognitive impairment. Outcomes will be reported both as continuous MoCA scores and as a binary classification (normal vs. impaired).	From enrollment to three-year follow-up, six-year follow up
Appendicular skeletal muscle mass	Appendicular skeletal muscle mass (ASM) will be assessed by bioimpedance analysis (BIA), with height-adjusted cutoffs of <7.0 kg/m² in men and <5.7 kg/m² in women defined as low ASM. Results will be reported as both continuous measures (kg/m²) and categorical measures (normal or low ASM).	From baseline to three-year follow-up, six-year follow-up
Grip strength	Grip strength will be assessed using a handheld dynamometer, with cutoffs defined as <28 kg for men and <18 kg for women. Results will be reported as continuous measures (kg).	From baseline to three-year follow-up, six-year follow-up
Sarcopenia	Sarcopenia will be defined as the combined presence of low ASM and low grip strength. Results will be reported as a binary outcome (yes/no).	From baseline to three-year follow-up, six-year follow-up

Collaborators and Investigators

• Sponsor: National Health Research Institutes, Taiwan
• Investigators: Principal Investigator: Hsueh-Ting Chiu, PhD, National Health Research Institutes, Taiwan

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2025
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2028

Study Registration Dates

• First Submitted: August 17, 2025
• First Submitted That Met QC Criteria: September 1, 2025
• First Posted (Actual): September 3, 2025

Study Record Updates

• Last Update Posted (Actual): April 8, 2026
• Last Update Submitted That Met QC Criteria: April 6, 2026
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Keywords: Cognitive decline; Sarcopenia; Frailty; Healthy aging; Vegetarian diets; Plant-based diets
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Neuromuscular Manifestations; Mental Disorders; Pathologic Processes; Pathological Conditions, Anatomical; Neurocognitive Disorders; Cognition Disorders; Muscular Atrophy; Atrophy; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Frailty; Cognitive Dysfunction; Sarcopenia
• Other Study ID Numbers: EC1131206; IRB Approval Number (Other Identifier: WMC/ERC/IRB/157)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No