Omega-3 (or n-3) Fatty Acids-Triglycerides
Part 2

Omega-3 (or n-3) Fatty Acids Part 2

What Are They?

Omega-3 fatty acids are polyunsaturated fatty acids (PUFAs) found in certain fatty fish and vegetables.  There has been a significant amount of interest in the potential health benefits of increasing dietary intake of these fatty acids.  These potential benefits include:

• reduction in arrhythmias and sudden cardiac death
• reduction in triglyceride levels
• improvement in blood pressure control, certain autoimmune diseases, and depression

The best scientific evidence for potential benefit is that for reduction in arrhythmias and sudden cardiac death (see Part I, and for reduction in triglyceride levels (summarized below).

Types and Sources of Omega-3 Fatty Acids

Alpha-Linolenic Acid (ALA): Found in land-based sources such as green plants, soybeans, and flaxseed oil.

Eicosapentanenoic Acid (EPA) and Docosahexanoic Acid (DHA): found in fatty cold water fish such as tuna, salmon, mackerel, halibut, and sardines.

Evidence of Benefit

1. Reduction in Cardiac Events (see Part I for details)

• In summary, studies indicate that omega-3 fatty acids lower cardiovascular event rates. 

• The mechanism is thought to be an antiarrhythmic effect.

• The amount of intake found to have this benefit is ~1g per day from fatty cold water fish or from supplements (that provide EPA and DHA) and from vegetable oils and plants (that provide ALA).

2. Reduction in Serum Triglyceride Levels

• The omega-3 fatty acids EPA and DHA can be effective tools for lowering serum triglyceride levels.

• Omega-3 fatty acids reduce hepatic triglyceride synthesis.

• Because clinically significant reductions in serum triglycerides are usually difficult to achieve by only increasing fish consumption, fish oil supplements are usually also required.

• A recent meta-analysis concluded that based on average intake of 3-4 g/d of omega 3 fatty acids in capsules, the lipid effects are:

Referenc: Harris WS.  Am J Clin Nutr 1997; 65: 1645S.

• Fish oil capsules can be used in combination with the triglyceride-lowering drugs niacin and fibrates, as well as dietary fat restriction, to lower severe triglyceride elevations (>1000 mg/dL) to avoid acute pancreatitis.

• They should be the preferred triglyceride-lowering agent in hypertriglyceridemic HIV patients on antiretroviral drug therapy.

• There may be slight deterioration of glycemic control with high intakes of omega-3 polyunsaturated fats requiring adjustment of hypoglycemic therapy in diabetic patients.