Krill are tiny, shrimp-like crustaceans that flourish in the Antarctic Ocean and provide food for numerous aquatic animals. Oil made from krill has come on the market as an alternative to fish oil. Like fish oil, krill oil contains the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Krill also containsomega-6 fatty acids, an antioxidant in the carotenoid family called astaxanthin, and substances called phospholipids.

Many grains, fruits, vegetables, sea vegetables, and vegetable oils contain significant amounts of essential fatty acids, but krill oil is an especially rich source.

Carotenoids are also found in many foods, especially yellow/orange and dark green fruits and vegetables. They are not essential nutrients (except insofar as some can be converted to vitamin A), but they might offer some health benefits.

Phospholipids are utilized in the body for numerous purposes, but they are not essential nutrients.