IBS affects people of all ages, although it tends to start before 35, perhaps due to the lifestyle shifts that occur as you transition into college and your first jobs, says Mark Larson, M.D., a gastroenterologist at the Mayo Clinic. “In your 20s and 30s, so many things are changing. The anxiety about the future and relationships is much more intense, and your gut takes a hit from all that stress.” Learn more about the signs, symptoms and treatment. Do you suffer from IBS? Have any tips for others facing the same struggle?