Nordic Naturals Ultimate Omega®-D3 provides exceptionally high levels of the omega-3 essential fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in addition to 1000 I.U. of vitamin D3 Vitamin D3 (or cholecalciferol) is the natural form of vitamin D produced by the body, and is better absorbed and utilized than other forms. In one delicious serving the double-strength EPA+DHA means fewer soft gels and the added natural vitamin D3 for strong bones and a healthy immune system.