1- Objectives: Assessing the effect of probiotics on mental health, stress oxidative and inflammatory indices in Petrochemical staff;
2- Design: Double-blinded Randomized Clinical Trial;
3- Setting, conducting and intervention: To conduct this study, the staff of Petrochemical Research & Technology Co., aging between 20 - 60, was invited. After signing the Consent Form by the eligible persons, 35 labors were randomly divided into three groups, to receive “100 grams of probiotics yogurt + placebo” or “ordinary yogurt+ probiotics supplement” or “ordinary yogurt + placebo” for 6 weeks. All three groups were advised not to change their normal diet or activities. Fasting blood tests were performed on all three groups before and after intervention. The 24-Hour Dietary Recall Questionnaire (to investigate the energy and nutritional intake), the International Physical Activity Questionnaire (IPAQ), and anthropometric data including weight, height, BMI and blood pressure have been completed at the beginning of the study and also at the end of the sixth week;
4- Main inclusion criteria: Having good physical health conditions and not taking any nutritional supplements in the last two months, and not taking any medicine (anti-depression, NSAID, etc.);
Main exclusion criteria: Not following the treatment (using less than 80% of yogurts or supplements);
5- Main outcome measures: It seems that Probiotics causes the decrease in inflammatory factors and stress oxidative, and also have a positive effect on mental health.