- Designed for your Health. Seven Seas Improved One-A-Day formula contains 480 mg of Fish Oil and Cod Liver Oil combined, a source of Omega-3 which helps support the health of your heart, brain and vision, It also includes the UK Government recommended level of vitamin D (10µg) to help support your immune system, These capsules contain 120 mg of Omega-3 and now, even higher levels of EPA and DHA