Objective To determine how a vegetarian diet affects stroke incidence in 2 prospective cohorts and to explore whether the association is modified by dietary vitamin B₁₂ intake. Methods Participants without stroke in the Tzu Chi Health Study (cohort 1, n = 5,050, recruited in 2007–2009) and the Tzu Chi Vegetarian Study (cohort 2, n = 8,302, recruited in 2005) were followed until the end of 2014. Diet was assessed through food frequency questionnaires in both cohorts at baseline. Stroke events and baseline comorbidities were identified through the National Health Insurance Research Database. A subgroup of 1,528 participants in cohort 1 were assessed for serum homocysteine, vitamin B₁₂, and folate. Associations between vegetarian diet and stroke incidences were estimated by Cox regression with age as time scale, adjusted for sex, education, smoking, alcohol, physical activities, body mass index (only in cohort 1), hypertension, diabetes, dyslipidemia, and ischemic heart diseases. Results Vegetarians had lower serum vitamin B₁₂ and higher folate and homocysteine than nonvegetarians. In cohort 1, 54 events occurred in 30,797 person-years follow-up. Vegetarians (vs nonvegetarians) experienced lower risk of ischemic stroke (hazard ratio [HR], 0.26; 95% confidence interval [CI], 0.08–0.88). In cohort 2, 121 events occurred in 76,797 person-years follow-up. Vegetarians (vs nonvegetarians) experienced lower risk of overall stroke (HR, 0.52; 95% CI, 0.33–0.82), ischemic stroke (HR, 0.41; 95% CI, 0.19–0.88), and hemorrhagic stroke (HR, 034; 95% CI, 0.12–1.00). Our explorative analysis showed that vitamin B₁₂ intake may modify the association between vegetarian diet and overall stroke (p interaction = 0.046). Conclusion Taiwanese vegetarian diet is associated with a lower risk of ischemic and hemorrhagic strokes.

Plant-based diets may target multiple pathways in gout pathogenesis (uric acid reduction and anti-inflammation) while improving gout associated cardiometabolic comorbidities. We aim to prospectively examine the relationship between a vegetarian diet and gout, and to explore if this relationship is independent of hyperuricemia. We followed 4903 participants in the Tzu Chi Health Study (Cohort1, recruited in 2007-2009) and 9032 participants in the Tzu Chi Vegetarian Study (Cohort2, recruited in 2005) until end of 2014. Baseline serum uric acid was measured in Cohort1. Vegetarian status was assessed through a diet questionnaire that includes dietary habits and a food frequency questionnaire. Incidence of gout was ascertained by linkage to the National Health Insurance Database. Hazard Ratio of gout in vegetarians versus nonvegetarians was assessed by Cox regression, adjusted for age, sex, lifestyle and metabolic risk factors. Hyperuricemia was additionally adjusted in Cohort1. In Cohort1, lacto-ovo vegetarians had the lowest uric acid concentration, followed by vegans, then nonvegetarians (men: 6.05, 6.19, 6.32 mg/dL, respectively; women: 4.92, 4.96, 5.11 mg/dL, respectively); 65 gout cases occurred in the 29,673 person-years of follow-up; vegetarians experienced a lower risk of gout (without adjustment for hyperuricemia: HR: 0.33; 95% CI: 0.14, 0.79; with adjustment for hyperuricemia: HR: 0.40; 95% CI: 0.17, 0.97). In Cohort2, 161 gout cases occurred in the 83,019 person-years follow-up, and vegetarians also experienced a lower risk of gout (HR: 0.61; 95% CI: 0.41, 0.88). Taiwanese vegetarian diet is associated with lower risk of gout. This protective association may be independent of baseline hyperuricemia. URL: https://www.clinicaltrials.gov. Unique Identifier: NCT03470584.

Vegetarian diets may lower symptomatic gallstone disease via cholesterol lowering. This study aimed to examine the risk of symptomatic gallstone disease (GSD) in Taiwanese vegetarians vs. nonvegetarians in a prospective cohort and to explore if this association is related to cholesterol concentration. We prospectively followed 4839 participants, and in the 29,295 person-years of follow-up, 104 new incident GSD cases were confirmed. Diet was assessed through a validated food frequency questionnaire. Symptomatic GSD was ascertained through linkage to the Taiwan National Health Insurance Research Database. Blood cholesterol profiles were measured at recruitment. Cox regression was applied to assess the effect of diet on symptomatic GSD, adjusting for age, education, smoking, alcohol, physical activities, diabetes, kidney diseases, body mass index, lipid-lowering medication, and hypercholesterolemia. Vegetarian diet was associated with a decreased risk of symptomatic GSD compared with nonvegetarian diet in women (hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.28–0.96) but not in men. In women, nonvegetarians with hypercholesterolemia had 3.8 times the risk of GSD compared with vegetarians with normal cholesterol (HR, 3.81, 95% CI, 1.61–9.01). A vegetarian diet may therefore protect against GSD independent of baseline hypercholesterolemia. A nonvegetarian diet and hypercholesterolemia may have an additive effect in increasing GSD risk in women.

In order to determine whether Taiwanese vegetarian diets reduce the risks of depression, we analyzed data from the Tzu Chi Vegetarian Study (TCVS), which is a prospective cohort study following 12,062 participants from the Buddhist Tzu Chi Foundation of Taiwan since 2005. The cohort was prospectively followed by linking to the National Health Institute Research Database (NHIRD) of Taiwan and hazard ratios of depression between vegetarian and non-vegetarian groups were calculated by Cox proportional hazards regression. We assessed dietary intake using a detailed food frequency questionnaire (FFQ). Incident depression was ascertained through linkage to NHIRD which had claim records with the International Classification of Diseases, and a total of 3571 vegetarians and 7006 non-vegetarians were included in this analysis. Compared with non-vegetarians, the vegetarian group had a lower incidence of depressive disorders (2.37 vs. 3.21 per 10,000 person-years; adjusted hazard ratio (aHR): 0.70; 95% confidence interval (95% CI): 0.52–0.93). Thus, Taiwanese vegetarians had a lower risk of developing subsequent depressive disorders compared with non-vegetarians. This indicated that diet may be an important measure for the prevention of depression. However, to generalize to the global population requires further study.

Objectives: Vegetarian diets have been shown to improve insulin resistance and reduce body weight, but the effects on nonalcoholic fatty liver require further confirmation. We aim to investigate the association between vegetarian diets, major food groups, and nonalcoholic fatty liver, and to compare the degree of liver fibrosis between vegetarians and nonvegetarians in those with fatty liver. Materials and Methods: We analyzed cross-sectional data from the Tzu Chi Health Study which included 2127 nonvegetarians and 1273 vegetarians who did not smoke or habitually drink alcohol and had no hepatitis B or hepatitis C. Fatty liver and liver fibrosis were determined using ultrasonography and the nonalcoholic fatty liver disease fibrosis score, respectively. Diet was assessed through a validated food frequency questionnaire. Results: Vegetarian diets were associated with lower odds of fatty liver (odds ratio = 0.79, 95% confidence interval: 0.68–0.91) after adjusting for age, gender, education, history of smoking and alcohol drinking. Adjustment for body mass index (BMI) attenuated the protective association. Vegetarians had less severe fibrosis than nonvegetarians. Replacing a serving of soy with a serving of meat or fish was associated with 12%–13% increased risk, and replacing a serving of whole grains with a serving of refined grains, fruits, and fruit juice was associated with 3%–12% increased the risk of fatty liver. Conclusion: Vegetarian diets, replacing meat and fish with soy, and replacing refined carbohydrates with whole grains, may be inversely associated with nonalcoholic fatty liver related to BMI.

The number of people living with dementia globally is increasing rapidly, and there is no effective therapy. Dietary pattern is one important risk factor for the development and progression of dementia. We undertake this study to determine whether Taiwanese vegetarian diet in midlife affects dementia incidence in later years in a prospective cohort. We followed 5710 participants (average age less than 60) in the Tzu Chi Vegetarian Study (TCVS). We started recruiting in 2005 and followed until the end of 2014 when the database changed from ICD-9-CM to ICD-10-CM codes. The incidence of dementia was obtained through linkage to the National Health Insurance Research Database. We used Cox proportional hazards regression to estimate the hazard ratio of dementia between vegetarians and nonvegetarians. There were 121 cases of dementia (37 vegetarians and 84 nonvegetarians) diagnosed. Vegetarians were associated with reduced risk of clinically overt dementia compared with nonvegetarians (hazard ratio = 0.671, confidence interval: 0.452–0.996, p < 0.05) after adjusting for gender, age, smoking, drinking, education level, marriage, regular exercise, and comorbidities with stepwise regression.