Do omega-3 fatty acids affect blood lipoproteins?

They lower trigs: They lower triglycerides.

Several actions: Omege 3 fish oils are most helpful in lowering triglycerides, some people have genetically high triglycerides, and they can also be high for people who are diabetic. Triglycerides are a different type of fat than cholesterol, that is an independent risk for heart problems, and possibly pancreatitis if they are really high. Fish oil can dramatically reduce them, and may also mildly lower your ldl.

Many ways: At common doses (1g epa/dha) of fish oil there are not major changes in lipids/lipoproteins. However, at higher doses (2-4g epa/dha), tirglycerides may be decreased by 30-50% and while ldl-c may staty the same or increase, LDL particle number (ldl-p) stays the same or decreases.

FishOils Lower Trigs: Omega3 fatty acids at high doses (2-4 gms/day) do lower tg's, but are most effective when the tg'sare elevated >500mg/dl. At this level they can lower tg's up to 45%. The effect is seen with fish based omega3's (epa & dha) not plant based (eg. Flax seed oil). There is a dose response seen. For each gram of 03's, about 10% additional reduction in triglycerides. Fish burp can be a side effect.

EPA Best Evidence: Both EPA & DHA, from phytoplankton, at very high (i.e. Purified Rx) doses, tend to ↓ the triglyceride concentrations in blood. EPA (without DHA & all the other non-beneficial fats in common fish oil) has a track record of also ↓ing LDL particle number, even at lower doses & >35 trials show ↓ed mortality rates. Even more effective for ↓ing triglycerides is greatly ↓ing all carb foods & ↓obesity.