This study investigated the effect of switching normal diet to vegetarian diet rich in vegetables and fruits for school foodservice and home meal on the nutritional status, bowel habit improvement and stress reduction of teachers and adolescents. A total of 40 research subjects (26 students, 14 teachers) from one middle school voluntarily participated in the research. Questionnaire surveys and blood analysis were conducted before and after a 12-week vegetarian diet period. The participants were asked on their dietary habit, bowel habit and stress measurement. After 12 weeks, reduction of BMI (kg/m²) in the students (p < 0.05) and reduction of TC (mg/dL) in both teachers and students (p < 0.05) were observed. Also reduction of LDL-C (mg/dL) was observed in the teachers (p < 0.05) whereas serum calcium and Vitamin B₁₂ was increased in the students and teachers (p < 0.005). The teacher's stress level was reduced (p < 0.05) after the 12-week vegetarian diet. As for the changes in bowel habit, the number of the students and teachers classified as experiencing functional constipation was decreased respectively from 10 to 7, from 7 to 5. Based on the result, it is considered that the vegetarian diet rich in fruits and vegetables improved general health status of study subjects suggesting that such a dietary habit would substantially contribute to improving nutritional status and bowel habit.