Omega-3 fatty acids are essential polyunsaturated fatty acids (PUFA). These PUFAs can not be synthesized by the human body but has many health benefits. The health effects have been extensively documented and probably the most known effect of omega-3 PUFAs is to reduce the risk for cardiovascular diseases. There are also indications that omega-3 PUFAs may lower the risk for dementia and mitigate depression.

The most important omega-3 PUFAs in the human diet are:
1. Alpha-linolenic acid (ALA)
2. Eicosapentaenoic acid (EPA)
3. Docosahexaenoic acid (DHA)

High concentrations of EPA and DHA are found in fish and shellfish. EPA and DHA in fish oil are easily absorbed by the human body. It is known that these PUFAs have different effects.

For instance, EPA is metabolized to eicosanoids that regulate fundamental physiological processes such as cell division and growth, blood clotting, muscle activity, and the secretion of digestive juices and hormones. Eicosanoids derived from EPA may reduce certain inflammatory processes that can lead to heart attacks and strokes.