Inclusion Criteria:  Diagnosed and under treatment for COPD with regular maintenance therapy. Postbronchodilator FEV1-FVC ratio less than 0.70 the last 3 months. FEV1<90%. Current smoker or ex-smoker at least 10 pack-years. COPD Assessment Test score level (CAT) ≥10. Patients with overlapping COPD and asthma disease may be included. Speaks fluent Norwegian. Signed informed consent and expected cooperation of the patients for the treatment and follow up must be obtained and documented according to ICH GCP, and national/local regulation.  Exclusion Criteria:  Evidence and/or diagnose of clinically significant uncontrolled non-pulmonary disease.  Myocardial infarction or stroke within the last 12 months, angina pectoralis diagnosed < 3 months or unstable angina Stage 4 of Congestive Heart Failure according to The New York Heart Association (NYHA) (severe heart failure with poor outcome and decreased survival rate). Cancer diagnosed within the last 12 months (except basal cell carcinoma of the skin), and/or ongoing active cancer therapy. Severe liver disease Severe autoimmune diseases requiring immunosuppressant treatment. Pulmonary fibrosis, interstitial lung disease, pulmonary hypertension, sarcoidosis, or significant bronchiectasis. Treatment with oral steroid < 1 month prior to baseline visit. Oral/intravenous antibiotics < 1 month prior to baseline visit. Immunosuppressant therapy such as Cyclosporine and Azathioprine. Consumption regularly of fish/krill oil (liquid, capsule, powder) as an oral supplement < 1 month prior baseline visit. Known fish or shellfish allergy. Participant in any other clinical study. Inflammatory bowel disease (Crohn's disease, UC, microscopic colitis), celiac disease, malabsorption, lactose intolerance. Severe cognitive impairment where the participants are not able to comply to protocol. Any reason why, in the opinion of the investigator, the patient cannot participate, or is not in the patient's best interest.