Immune System

Omega-3 fatty acids are powerful allies of the immune system. In fact, several researches have demonstrated their ability to modulate both immune response and inflammation.

The first data in this regard date back to 1932, when it was observed that some inflammatory states could be counteracted by treatment with Omega-3 eicohexapentaenoic acid (EPA) and docosahexaenoic acid (DHA).



Why immunity and inflammation?

Inflammatory processes represent a generic, nonspecific defense mechanism that helps the body counter any aggression, whether traumatic, chemical, or microbial.


Its basic symptoms, described as early as the 1st century AD in De Artibus by Aulus Cornelius Celsus, are 4:


  • rubor (redness);
  • calor (increased temperature of the inflamed area);
  • tumor (swelling);
  • dolor (pain). 


A fifth symptom was later added to these: functio laesa (loss of function).


Specific immunity, on the other hand, is a more sophisticated defense system that can be divided into 2 mechanisms:


  • Humoral or antibody immunity, based on the production of antibodies;
  • immunity mediated by cells belonging to the body's defense system.


Both inflammation and specific immunity can be promoted by several factors. The triggering stimulus causes the production of molecules that signal to the body the presence of inflammation: interleukins and eicosanoids.


And this is where fatty acids come in. Indeed, the balance between Omega-3 and Omega-6 (another class of fats) regulates the production of several inflammatory molecules. Specifically, Omega-3s inhibit the production of eicosanoids and have an anti-inflammatory action; Omega-6s, on the other hand, promote inflammation.




The Role of Omega-3s



Years of studies have elucidated the mechanism by which Omega-3s modulate immune response and inflammation.


Their effect depends on a number of factors, such as the type and amount of fatty acids introduced with the diet and the length of time supplements and dietary supplements are taken.


The results of early research were confirmed by clinical trials that demonstrated the effectiveness of Omega-3-rich fish oil supplements in modulating the activity of proinflammatory molecules and factors involved in immune response.




Omega-3 and rheumatic diseases


An interesting application of Omega-3s concerns rheumatic diseases triggered by autoimmunity.


Autoimmune diseases are so called because at their base is an abnormal response of the immune system, which attacks its own body.


Chronic inflammatory and autoimmune rheumatic diseases include the following:


All of these diseases have a chronic state of inflammation as a common denominator.


Overall, 1% of the population suffers from it, and women are affected 3 times more frequently than men.


Although in most cases the cause is unknown, it appears that individuals with these disorders are genetically predisposed to their development. This causes their immune system, stimulated by various factors, such as microorganisms, to trigger the abnormal inflammatory reaction that underlies these disorders.


Because white blood cells (i.e., immune system cells) and antibodies circulate in the blood, inflammation involves the whole body.


The benefits of Omega-3s for the immune system were summarized by Artemis Simopoulos, president of the Center for Genetics, Nutrition and Health in Washington, Washington, U.S., in a 2002 article in the Journal of the American College of Nutrition.


One of the first clues in this regard was the low rate of autoimmune and inflammatory diseases in the Eskimo populations inhabiting Greenland, whose diet is rich in fish high in Omega-3.


Reviewing the theory that the beneficial effect of fish oil is due to the ability of Omega-3s to modulate the activity of molecules with proinflammatory activities, Simopoulos concluded that treating autoimmune diseases with fish oil decreases their severity. At the same time, Omega-3s reduce the need to use anti-inflammatory drugs.


Simopoulus analyzed the following pathologies in his studies:

  • atherosclerosis
  • obesity
  • depression
  • rheumatoid arthritis
  • inflammatory bowel disease
  • asthma
  • psoriasis


Next, Trevor Mori and Lawrie Beilin summarized in the pages of Current Atherosclerosis Report the beneficial effects of EPA and DHA against inflammation, describing the clinical and experimental data available in the scientific literature.


In particular, the two experts pointed out that fish oil introduced through the diet reduces the formation of certain proinflammatory molecules, concluding that these Omega-3s could be really effective in treating inflammatory and autoimmune diseases.


Not only that, Mori and Beilin pointed out that EPA and DHA are also effective in improving blood vessel wall function. Dietary omega-3 intake reduces certain markers, indicating a reduction in inflammation that could explain the preventive effect of these fatty acids against cardiovascular disease.




Some examples of the effectiveness of Omega-3s



Studies that have shown the effectiveness of treating inflammation with Omega-3 are diverse.


Early evidence comes from studies in animal models, many of which suggest that moderate dietary restriction or reduction in the number of calories consumed extends average lifespan by delaying the onset of immune system dysfunction associated with aging.


In particular, the average lifespan depends on both the amount and type of fatty acids introduced in the diet.


Such findings could also have important implications in the treatment of obesity, diabetes, cancer and in aging.


But studies conducted in humans were available as early as 2003. Specifically, research published in the American Journal of Clinical Nutrition showed that, in healthy individuals, consumption of fish oil for four consecutive weeks decreased the production of proinflammatory molecules as well as the proliferation of a particular class of white blood cells, the lymphocytes. The same research also reached similar conclusions by administering a mixture of EPA and DHA.


Not only that, the study authors also showed that it is not necessary to take antioxidants to achieve these results. In fact, simultaneous intake of these other molecules does not affect the anti-inflammatory and immune benefits of Omega-3.


Regarding some diseases, simultaneous intake of fish oil and anti-inflammatories reduces markers of inflammation. This is the case with Crohn's disease.


Over time, clinical studies have multiplied in order to establish with certainty the anti-inflammatory mechanisms promoted by Omega-3 intake. Research to date has shown that intake of these fatty acids has no major side effects.




Omega-3, resolvins and inflammation


A study published in the Journal of Experimental Medicine in 2005 identified a class of lipids with anti-inflammatory functions in humans derived precisely from a fatty acid contained in fish oil.


The authors of the research showed that, once in cells, Omega-3 fatty acids are converted by an enzyme into molecules called resolvins. These factors, which are also activated by taking aspirin, are able to reduce inflammatory processes in guinea pigs.


Intake of Omega-3 and aspirin also causes the accumulation of resolvins in human plasma. Not only that, in humans, resolvin E1 inhibits the migration of inflammatory cells to inflamed sites and their ability to activate other cells involved in the inflammatory response.


Subsequent studies have revealed that both resolvins and some derivatives of DHA (the docosatrienes) have potent anti-inflammatory and immunoregulatory effects. Therefore, experts have emphasized their important therapeutic potential.


Finally, a 2006 study showed that EPA has a dose-dependent effect: as age increases, the ability to incorporate EPA into lipids contained in blood plasma and certain cells involved in immunity also increases. This increases the sensitivity of the immune system to the benefits of these Omega-3s.