Pain in Endometriosis And the Relation to Lifestyle

The goal of this clinical trial is to investigate the effect of an anti-inflammatory diet and cognitive behavioral therapy (CBT) on pain symptoms, health related quality of life and the effect on inflammatory characteristics in serum and menstruum samples as well as the effect on the gut and vaginal microbiome in women with endometriosis. In addition, we want to investigate the differences in stress (measured by hair cortisol levels), inflammatory markers in peripheral blood, menstrual effluent, and the vaginal and intestinal microbiome between persons without and with endometriosis. Participants will be randomized between standard care (control group), standard care and an anti-inflammatory diet intervention, or standard care, an anti-inflammatory diet intervention and CBT or CBT alone. Participants will follow an anti-inflammatory diet based on the Dutch Dietary Guidelines or CBT or a combination of both interventions for 12 weeks. They will receive personalized dietary advice from a dietician and recipes will be available. cognitive behavioral therapy will be administered in a total of seven individual sessions led by a psychotherapist. The content of these sessions will be psycho-education regarding pain mechanisms (and diet).