Inclusion Criteria:  Diagnosed with breast cancer at "Brystkirurgisk Afdeling" at Rigshospitalet and Herlev Hospitals (within the last 30 days). Advised (and accepted) to receive neo-adjuvant treatment Primary unilateral breast cancer Treatment is expected to be curative Is expected to be able to attend surgery  Exclusion Criteria:  Allergic to soy Celiac disease Inflammatory bowel disease Not understanding Danish (patient material and questionnaires are in Danish) Prior diagnosis of breast cancer Use of dietary supplements containing lignans or isoflavones three months prior to diagnosis