1. Golestan Research Center of Gastroenterology and Hepatology (GRCGH), Golestan University of Medical Sciences (GOUMS), Gorgan, Iran
2. Digestive Disease Research Center, Digestive Research Institute, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
3. Epidemiology and Biostatistics department, School of Public Health, Knowledge Utilization Research Center, Tehran University of Medical Sciences, Tehran, Iran
4. Digestive Diseases Research Center, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
5. Department of Clinical Nutrition, School of Nutritional Sciences and Dietetics, Tehran University of Medical Sciences, Tehran, Iran