Immune System and Inflammation

One of the functions of our immune system is to fight viruses, fungi, bacteria and pathogenic parasites. It does this by releasing inflammatory cytokines during infections. If our immune system, and especially our gastrointestinal system, is healthy, there is a lower risk of autoimmunity.

There are two main types of immunity: innate (natural immunity) and acquired (adaptive immunity). Immune cells are concentrated in lymphoid organs (lymph nodes, thymus, spleen, and gastrointestinal lymphoid tissue) and in the circulation, as well as other parts of the nervous system and body.

The innate immune system is a first line of defense against infection that works by preventing and eliminating infectious pathogens. Examples of the innate immune system include skin, phagocytic cells (neutrophils, eosinophils, basophils), monocytes, and macrophages.

The acquired immune system, unlike the innate immune system, has a "memory" and previous exposure to pathogens improves its subsequent response. Although the acquired immune system responds slower than the innate immune system, once it becomes efficient, the effect is lasting. Acquired immunity includes antibodies, which help pathogens bind to and neutralize each other.  In addition, acquired immunity activates complement proteins, promoting the activation of phagocytes and consequently eliminating pathogens.

If an invading pathogen is inside a host cell, it means that it has escaped antibody defense, also known as humoral immunity. However, T cells along with auxiliary T cells (indicated by the presence of CD4 protein on their surface) can eliminate these pathogens.  Type 1 auxiliary T cells activate macrophages, cytotoxic T cells (CD8+) and natural killer cells; type 2 auxiliary T cells activate mast cells and basophils; while regulatory T cells help suppress inflammation and immunity.

Inflammation is the immune system’s response to harmful stimuli, such as pathogens (harmful bacteria and viruses), damaged cells, toxic compounds, or irradiation, and acts by eliminating harmful stimuli and initiating the healing process. Inflammation is therefore a vital defense mechanism for health, but this response must be adequate and moderate.  An effective immune system to prevent and eliminate infectious agents is necessary, however, if the immune system responds by overactiving due to dietary or environmental allergens, it then causes an autoattack on the body.

Omega-3: Omega-6 Balance and Inflammation

Throughout evolution there has been a balance between omega-6 and omega-3 fatty acids with a ratio of 1-2:1 omega-6:omega-3. However, the current Western diet is high in omega-6 fatty acid consumption and inadequate in omega-3 fatty acids; with a ratio of 16-20:1 omega-6:omega-3, leading to a proinflammatory state.  If we add to this a high consumption of sugars, which leads to obesity, we result in a chronic state of low-grade inflammation.

Omega-6 fatty acids are proinflammatory and prothrombotic, while omega-3 fatty acids are anti-inflammatory and antithrombotic. Additionally, omega-3 fatty acids produce specialized lipid mediators, namely resolvins, protectins and maresins, which are potent anti-inflammatory agents.

Eating a typical western diet generates immune cells (neutrophils, lymphocytes, and monocytes) that contain ~20% fatty acids such as arachidonic acid with only 1% EPA and 2.0-2.5% ALA and DHA.  However, supplementing the diet with 2 grams of ALA/EPA/DHA for 12 weeks has been shown to increase phospholipid long-chain omega-3 fatty acids to about 3.5% EPA and 3.5% DHA. Therefore, an increase in omega-3 polyunsaturated fatty acids in the diet will reduce the omega-6:omega-3 ratio in immune cells.

¿How to Increase Omega-3 Levels to Control Inflammation

The current diet is highly proinflammatory; therefore, it is essential to balance our diet in omega-6 and omega-3 fatty acids: 

  1. reducing the intake of oils rich in omega-6 fatty acids (corn oil, sunflower oil, safflower oil and soya oil),
  2. increasing the intake of oils rich in omega-3 fatty acids such as chia oil,
  3. increasing the intake of monounsaturated oils (olive oil, avocado oil and walnut oil),
  4. and decreasing consumption of ultra-processed foods that have an omega-6:omega-3 ratio >4:1.

It is essential that nutritionists, doctors, and other health professionals measure omega-6 and omega-3 fatty acids in their patients' red blood cell membrane phospholipids and educate them on how to ensure a healthy proportion of omega-6:omega-3 in their diet in order to decrease chronic inflammation and maintain a normal, and less inflammatory immune system.

For additional information, please contact: [email protected]


Simopoulos AP. Genetic Variation, Diet, Inflammation, and the Risk for COVID-19. Lifestyle Genom. 2021;14(2):37-42. doi: 10.1159/000513886. Epub 2021 Feb 2. PMID: 33530084; PMCID: PMC7900446.

 Gutiérrez S, Svahn SL, Johansson ME. Effects of Omega-3 Fatty Acids on Immune Cells. Int J Mol Sci. 2020 Oct 11;20(20):5028. doi: 10.3390/ijms20205028. PMID: 31614433; PMCID: PMC6834330.

 Calder PC. Omega-3 fatty acids and inflammatory processes.Nutrients. 2010 Mar;2(3):355-374. doi: 10.3390/nu2030355. Epub 2010 Mar 18. PMID: 22254027; PMCID: PMC3257651.