 STUDY PROCEDURE: A venous blood sample will be collected in a 10ml EDTA-tube. Then, each subject will be randomized to treatment with Efexor XR first and last two weeks 75 mg 1dd and from the third to the fifth week 75 mg 2dd or identical placebos for 8 weeks. Before starting and after finishing treatment, patients will be asked to fill out a questionnaire on intensity of their gastrointestinal complaints, current quality of life and anxiety and depression. 