The obvious place to begin looking was the effect of fish oils on blood fats like cholesterol and triglycerides. Studies examining the effects on cholesterol have been mixed. Most have found no effect or even a small increase in total cholesterol in subjects receiving fish oil supplements. At the same time, however, high intakes of fish oil consistently have been associated with decreased blood triglyceride levels, a factor which may be protective for some individuals. Investigating another direction, much research has focused on the ability of omega-3 fats to influence blood platelet aggregation.
Platelets are the constituent in blood that helps it clot.
This is important for wound healing. However, when blood becomes too sticky, it can further the progression of heart disease, especially in vessels injured with plaque formation. Research indicates that EPA in particular helps reduce the stickiness of blood platelets. Fish oils also appear to help stabilize heart rhythm, a factor that may be important in people recovering from heart attacks. This is one unanswered question.