Graves' disease (GD) is an autoimmune disease in which thyroid-stimulating antibodies cause overproduction of thyroid hormone. This leads to severe physical and psychological symptoms, in a relatively young patient group. The standard treatment of GD has remained unchanged for more than 50 years. Van der Spek: ‘There is a clear need for new and more effective treatment options for this debilitating disease.’ Her research goes into the intestines of GD patients to look for gut microbes (including bacteria, viruses, yeast and fungi) as a potential cause of GD. This could lead to new treatment options for this disease.