Sunday 13 December 2009, 23:21

The role of omega-3 fatty acids

Benefits of dietary omega-3 fatty acids

The role of omega-3 fatty acids

Omega-3 fatty acids are essential nutrients that body needs to grow and work properly. Three fatty acids compose the omega-3 family: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA). Alpha-linolenic acid is found in vegetable oils such as soybean, linseed and olive oils. The other two omega-3 fatty acids (EPA and DHA) are found in cold-water fish, fish oil and supplements.


Omega-3 fatty acids play anti-inflammatory and anti-hypertension roles. They are metabolized by cyclooxygenase into anti-inflammatory and vasodilator eicosanoids: prostaglandins PGE1 and PGE3 and prostacyclin PGI3. On the other hand, omega-6 fatty acids (found in vegetable oils but not in fish) are the precursors for pro-inflammatory and vasoconstrictor eicosanoids: prostaglandin PGE2, thromboxane A2 and leukotriene B4. Omega-3 and omega-6 fatty acids play therefore antagonist roles.


Since omega-6 and omega-3 fatty acids compete for the same enzyme to eventually be converted into pro- or anti-inflammatory eicosanoids respectively, the overall inflammatory state of the body is influenced by the ratio omega-6/omega-3. The ideal dietary ratio of omega-6 to omega-3 is approximately 4:1, as found in the Mediterranean diet which is rich in cold-water fish and natural oils. On the contrary, the existing ratio in the American and Northern European diets is nearly 20:1. This high ratio is responsible for overproduction of pro-inflammatory PGE2 and underproduction of anti-inflammatory PGE1 and PGE3.


There is evidence from many studies that a proper intake of EPA and DHA is associated with decreased blood pressure, lowered blood triglycerides levels, delayed atherosclerotic process, reduced mortality and improved outcomes in patients with cardiovascular diseases. Similar benefits are proposed for ALA as well, although there is not yet conclusive scientific evidence to support this assumption.


Although not supported by strong scientific evidence, omega-3 fatty acids seem to play a protective role in many other diseases, such as rheumatoid arthritis, asthma, cancer development, depression, eczema and psoriasis. However, before drawing a conclusion, additional researches are needed in these areas.


By Chiara De Carli

Category: Nutrition

Sign Up

Subscribe to our newsletter

Important news