Omega-3 and vitamin D contribute to the normal functioning of the immune system, keeping muscles and bones normal. Omega-3, EPA and DHA contribute to normal heart function. Omega-3 fish oil capsules contain vitamin D, which helps the immune system to function normally and keep muscle function and bones normal. In addition, the capsules contain omega-3 fatty acids EPA and DHA, which contribute to normal heart function. DHA helps to maintain normal brain function and maintain normal vision. The beneficial effects of EPA and DHA occur when at least 250 mg is daily consumed.