Tzu Chi Health Study (Diabetes and Cardiometabolic Health Components)

How did the study come about? The Tzu Chi Health Study (TCHS) began in 2007 with the goal of investigating the role of a vegetarian diet on health outcomes.

Founded in 1966, the Buddhist Tzu Chi Foundation is a leading humanitarian organization with a worldwide base of more than 5 million supporters and volunteers. Tzu means "compassion" and Chi means "relief". The organization has chapters in 47 countries on six continents, which carry out the missions of Charity, Medicine, Education, and Humanistic Culture, and delivered aid to 67 countries, to date. Today in Taiwan, there are six Tzu Chi hospitals: four large teaching hospitals (in Hualien, Dalin, Taipei, and Taichung), and two small community hospitals (in Kuanshan and Yuli). Tzu Chi has established in Taiwan a comprehensive educational system from pre-school to graduate school, including Tzu Chi University (housing now a leading medical school in Taiwan) and operates Da Ai (Great Love) TV, a global satellite television station that runs in part on proceeds from its on-going recycling program.

For reasons of compassion and environmental conservation, a vegetarian diet is suggested, but not required, for Tzu Chi Commissioners. This population of Commissioners is a non-smoking, non-drinking population, with a wide range of dietary practice: about 30% are vegetarians, 38% partial vegetarians, and 32% omnivores. A free comprehensive health examination is available for Tzu Chi commissioners at Tzu Chi hospitals every two years. TCHS was established at Dalin Tzu Chi Hospital, where both Commissioners and patients coming for health examinations have been invited to participate in the study.

This study provides a unique opportunity to examine the health of East Asian Vegetarians. Much evidence for the health effects of a vegetarian diet are currently from western populations, namely the Seventh Day Adventists and the British vegetarians, while there is very little evidence on East Asian vegetarians who consume a different vegetarian diet.

Who is in the sample? A total of 6002 subjects have enrolled in the study. More than 70% of the participants are Tzu Chi Commissioners. The female-to-male ratio is about 2:1.

How are the study subjects followed up? Participants are followed through several methods: (1) every three years, participants were invited back for detailed health examination. (2) Follow-up questionnaire sent to participants who did not return for health examination. (3) Linkages to the National Health Insurance Database and death registry.

What has been measured? Dietary, lifestyle and medical and family histories on diseases were obtained through a questionnaire, administered by interviewers. Biochemical and anthropometric data was collected through physical exams.

• Dietary questionnaire: A dietary questionnaire has been administered, with trained research dietitians as interviewers. The questionnaire was adopted from the National Nutrition Survey in Taiwan.
• Biochemical variables: CBC, fasting glucose, lipid profile (TCH, LDL, HDL, TG), BUN, Cr, ALT, AST, and UA. In addition, homocysteine, serum vitamin B12, folate, and C-reactive protein (CRP) are available for 1500 subjects.
• Blood: Extra blood samples have been obtained and stored for 3500 subjects and will be available for future investigation.
• Anthropometric variables: body weight, height, waist circumference, % body fat (with BIA), blood pressure, pulse wave velocity, bone mineral density through DXA (at spine for female and hip for male), lung function test (spirometric), abdominal sonography, colonoscopy, esophageal-gastro-duodenal-scopy, chest X-ray, KUB.

Inclusion criteria

• Adult individuals who came to Dalin Tzu Chi Hospital for health examination between 2007 to 2009.
• Willing to participate in the study, be interviewed on questionnaires on demographics, diet, and lifestyle; willing to release health examination data for study purpose, and willing to be followed-up on health outcome

Exclusion criteria

• Participants less than 18 years old.