Omega-3 Fatty Acids: Functions, Sources, Types, Benefits

Fatty acids, chain-like chemical molecules, are carboxylic acids with long hydrocarbon chains comprised of carbon, oxygen, and hydrogen atoms.

It is a component of lipids present in animals (butter, lard, beef, and so on), plants (corn oil, soybean, peanut, olive, and so on), and microorganisms. 

The length of hydrocarbon ranges from 10-30 carbons (usually 12 to 18). It has hydrophobic properties.

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Functions of Fatty Acids

The functions of fatty acids are:

  1. It plays a crucial role in the biological signaling pathway. The precursor of potent signaling mediators is lipid peroxidation.
  2. The metabolism of fatty acids acts as a cellular fuel source.
  3. Fatty acids store energy as fat droplets- composed of hydrophobic triacylglycerol molecules within adipocytes (specialized fat cells that store and metabolize lipids).
  4. It helps to form a cell membrane, also called a plasma membrane, which encloses all cells and the other related intracellular organelles. The cell membrane is composed of a phospholipid bilayer ( lipid molecules) comprised of two fatty acid chains bound to glycerol and a hydrophilic (head) phosphate group joined to a smaller hydrophilic (tail) compound (e.g., choline).
  5. It helps in protein modification: fatty acids interact with various proteins.

Types of Fatty Acids

There are three types of fatty acids:

  1. Saturated fatty acids
  2. Unsaturated fatty acids
  3. Trans fats

Saturated Fatty Acids

    • Saturated fatty acids are saturated with hydrogen and contain 12–22 carbon atoms. It is also known as bad or unhealthy fats because they are pernicious to our health, such as increased risk of heart disease and stroke.
    • It remains solid at room temperature.
    • Saturated fatty acids have a higher melting point than unsaturated fatty acids. Examples are lauric acid (CH3(CH2)10COOH), palmitic acid (CH3(CH2)14COOH), and stearic acid (CH3(CH2)16COOH).
    • Saturated fats containing foods include cheese, butter, milk, Coconut, Palm and palm kernel oils, Beef, Lamb, Pork, Skin of chicken and turkey, Lard, Full-fat dairy, Ice cream, Cream, and Some baked and fried foods.

    Trans Fatty Acids

      • There are two sources of trans fatty acids: natural and artificial (liquid oils). In industrial processes, artificial trans fats are converted into solids. 
      • Trans fatty acids are bad/ artificial fatty acids present in all processed foods. 
      • The primary dietary source is partially hydrogenated oils. 
      • It can cause the risk of heart disease, stroke, and type-2 diabetes.

      Unsaturated Fatty Acids

        • Unsaturated fatty acids are fatty acids that have one or more double bonds between carbons, such as alkenes.
        • It tends to be liquid at room temperature.
        • They are good or healthy fats because they are innocuous to our health.
        • Examples are Oleic (CH3(CH2)7CH=CH(CH2)7COOH), Linoleic (CH3(CH2)4(CH=CHCH2)2(CH2)6COOH), Linolenic (CH3CH2(CH=CHCH2)3(CH2)6COOH), and Arachidonic (CH3(CH2)4(CH=CHCH2)4(CH2)2COOH).

        Unsaturated fat breaks down into two types:

        1. Monounsaturated fatty acids
        • They are fatty acids containing one carbon-carbon double bond; most fatty acids are present in positions between 16 and 22 carbons in length containing a cis double bond.
        • The sources of monounsaturated fatty acids are Olive oil, Peanut oil, Canola oil, Safflower oil, Sesame oil, Avocado, Peanut butter, and many nuts and seeds.
        1. Polyunsaturated fatty acids (PUFAs)
        • Polyunsaturated fatty acids are fatty acids that comprise long chains of carbon atoms with a carboxyl group at one end and a methyl group at the other.
        • These fatty acids contain more than one double bond produced by plants and phytoplankton.
        • The two classes of polyunsaturated fatty acids (PUFAs) are: Omega-3 fatty acids (Tuna, Salmon, Trout, Herring, Sardines, Flaxseeds and flaxseed oil, Walnuts, and chia seeds ) and Omega-6 fatty acids (Safflower oil, Sunflower oil, Corn oil, Soybean oil, Sunflower seeds, pumpkin seeds).
        • The carbon-carbon double bond located between the third and fourth carbon atoms from the methyl end of the chain is called Omega-3 fatty acids (ω-3 fatty acids).
        • Omega-6 fatty acids (ω-6 fatty acids) are fatty acids in which the carbon-carbon double bond is present between the sixth and seventh carbon atoms from the methyl end of the chain. The Omega-6 fatty acid examples are Linoleic acid (C18:2n-6) and arachidonic acid (C20:4n-6).

          Omega-3 Fatty Acids (ω-3 Fatty Acids)

          Omega-3 fatty acids, also known as n-3s, mean the carbon-carbon double bond is present between the third and fourth end carbon atoms.

          • There are two ends in fatty acids: carboxylic acid (COOH) alpha end-initial of the chain and methyl (CH3) omega end-tail of the chain.
          • C60H92O6 is the molecular formula of omega-3 fatty acids, and the molecular weight is 909.39 g/mol.
          • Omega-3 fatty acids found in fish are long-chain, whereas Omega-3 fatty acids present in plants are shorter chains. Long-chain omega-3 enters more rapidly in the blood, and cells show fast effects. Short-chain omega-3 fatty acids convert into long-chain fatty acids.
          • Examples are Linoleic acid, Gamma linoleic, Arachidonic Acid, Conjugated linoleic acid, Alpha-linolenic acid, and Ocosahexaenoic acid.
          • In addition, Omega-3 supplements, such as Omega-3-acid ethyl esters, Boldfit Flaxseed omega-3 Supplement, Boldfit omega-3 Fish Oil, Lovaza, Vascazen, Omtryg can be ingested by those who do not eat omega-3-rich foods.
          Omega-3 Fatty Acids
          Omega-3 Fatty Acids

          Shelf life of Omega-3 Fatty Acids

          • Omega-3 fatty acids are essential nutrients and healthy polyunsaturated fats that provide crucial functions to our health. 
          • The shelf life of omega-3 fatty acids containing food has short shelf life. 
          • If this food keeps in contact with the air for a longer time, it will oxidize; however, there will be a loss of nutrition in that food. 
          • Moreover, it gets affected by light, heat, and moisture, which can cause a loss of nutrition.
          • So, If some foods, such as fish, eggs, meat, and seeds, are kept for a long time, they should be stored in a cold space and sealed place. But it prefers to eat as soon as possible.

           Functions of Omega-3 Fatty Acids

          1. It helps in the movement of muscles, such as relaxation and contraction.
          2. It helps the blood from clotting excessively.
          3. It helps in digestion.
          4. It lowers lipid amounts, such as cholesterol, LDL, and triglycerides, circulating in the bloodstream.
          5. It helps in growth and cell division.
          6. Its function is to transport calcium and other substances in and out of cells.
          7. Omega-3 fatty acids are an essential component of phospholipids, a part of the cell membrane that helps form the structure. Moreover, it supports the interaction between cells.
          8. They help to provide energy to our body by transferring fatty acids into the mitochondria that uphold a healthy body system, such as the cardiovascular and endocrine systems.
          9. It decreases the aggregation of platelets and inhibits thickening of the arteries.
          10. It has an antioxidant that protects the body’s cells from harmful substances.
          11. It decreases the production of messenger chemicals called cytokines. It has anti-inflammatory, immunomodulatory, hypolipidemic, anti-cancer, and hepatoprotective properties.
          12. It enhances the chemical activity derived from endothelial cells (endothelium-derived nitric oxide) that causes arteries to relax and dilate.
          13. DHA alters the G-protein coupled signaling pathway that helps to regenerate rhodopsin and maintain healthy vision.
          14. EPA serves as a precursor for many signaling molecules and helps retinal function.
          15. It reduces high triglycerides by influencing total body lipid accretion.

          Sources of Omega-3 Fatty Acids

          The most common foods are: 

          1. Fatty fish (Mackerel, Salmon (farmed, Atlantic), Herring (Atlantic), Anchovy, Salmon (wild, Atlantic), white fish, tuna (bluefin), oysters (rich in zinc, copper, and vitamin B12), Halibut (Greenland), Sardines rich in  vitamin B12, 24% for vitamin D, and 96% for selenium (Atlantic, canned in oil), Tuna (Albacore, canned in water), Bluefish, Striped bass, Rainbow trout (wild), Tuna (light, canned in water).
          2. Fish oils (Egg oil, Fish oils, Krill oil, Squid oils)
          3. Flax seeds and flax seed oil (often used as an omega-3 supplement)
          4. Chia seeds rich in manganese, selenium, magnesium, and other nutrients
          5. Edamame, cereals
          6. Soybean (rich in riboflavin, folate, potassium, vitamin K, and magnesium) and Soybean oil
          7. Walnuts (rich in fibers, copper, manganese, and vitamin E)
          8. Caviar includes fish eggs or roe (a good source of choline)
          9. Anchovies (a good source of niacin and selenium)
          10. Avocado
          11. Oatmeal
          12. Broccoli
          13. Veffies (Spinach, Cauliflower, brussels sprouts)

          Types of Omega-3 Fatty Acids

          There are three types of omega-3 fatty acids:

          Eicosapentaenoic acid (EPA)

            • EPA is a long-chain, marine-derived omega-3 fatty acid consisting of 20 carbons, so it is called C20:5n-3. 
            • The chemical name is all-cis-5,8,11,14,17-eicosapentaenoic acid. It converts into DHA.
            • It is essential for the functioning of our inflammatory system, which is responsible for maintaining the immune response to attacks or infections.
            •  The sources of EPA are fatty fish, fish oils, and krill oils; However, Originally, they were synthesized by microalgae, not by the fish. 
            • Omega-3 fatty acids provide energy to our body and produce eicosanoids.

            Docosahexaenoic acid (DHA)

              • DHA is an essential, long-chain, marine-derived omega-3 fatty acid consisting of 22 carbons, so it is called C22:6n-3. 
              • The chemical name is all-cis-4,7,10,13,16,19-docosahexaenoic acid. 
              • It occurs in animal products like fatty fish and fish oil, while meat, eggs, and dairy from grass-fed animals in a significant amount. 
              • It is present in the retina, brain, skin, testicles, and sperm. Mainly, it is highly present in the cell membrane of the retina. 
              • They are not present in vegetarian and vegan products. It helps in the normal development and retina function.
              • It is essential for the functioning of our brain and nervous system.

              Alpha-linolenic acid (ALA)

                • ALA, plant-derived omega-3 fatty acids, consists of 18 carbon atoms and three double bonds (18:3) called C18:3n-3 (n-3 means omega fatty acids). 
                • The active conversion of ALA (precursor of EPA and DHA) is limited (less than 15 %)- converted into EPA and then to DHA; our body uses it as energy and is from the diet.
                • The source of ALA is plants like flaxseed, soybean oil, chia seeds, walnuts, Algae oil, edamame, hemp seeds, mustard oil, olive oil, broccoli (raw and cooked), raw Cauliflower, lettuce, purslane, raw spinach, grains (barley bran, corn germ, rice, wheat bran), avocados, raspberries, strawberries), and canola oils. 
                • Fish acquire omega-3 fatty acids in their tissues when they consume phytoplankton that previously devoured microalgae. 

                Benefits of omega-3 fatty acids

                Omega-3 fatty acids play a crucial role in our body for maintaining a healthy lifestyle. The benefits of omega-3 fatty acids are:

                1. It reduces the risk of cancer, obesity, strokes, pneumonia, and cardiovascular problems such as heart disease.
                2. It maintains the fluidity of cell membranes.
                3. It reduces morning stiffness, swollen joints, ulcerative colitis, Crohn’s disease, psoriasis, and rheumatoid arthritis.
                4. It helps in not forming stones in the kidneys.
                5. It maintains mental health disorders, such as tackling depression and anxiety. Moreover, it also reduces tiredness and sadness.
                6. It is an essential source for providing nutrition to dry and damaged hair.
                7. It reduces menstrual cramp pain.
                8. It enhances the development of the brain and memory power.
                9. It helps to maintain cholesterol levels.
                10. It lowers blood inflammation by the consumption of marine-based omega-3 fatty acids.
                11. It improves the quality of life by controlling appetite and weight after ingesting supplements.
                12. It promotes brain health during pregnancy, which is beneficial to the child. It improves cognitive development and communication skills.
                13. It helps to improve eye health and reduce the macular degeneration risk.
                14. It decreases the risk of attention deficit hyperactivity disorder (ADHA).
                15. It provides good sleep. 

                Symptoms of Omega-3 deficiency

                1. It causes cardiovascular problems.
                2. It leads to Weight gain and obesity.
                3. It Leads to Alzheimer’s disease due to poor memory.
                4. It can cause depression and mood swings.
                5. It causes joint pains and cramps.
                6. It increases the cholesterol level.
                7. It can cause autoimmune diseases.
                8. It can cause rough, scaly skin and dermatitis.
                9. It might cause sleep deprivation. 
                10. It might cause improper brain development and functioning that results in Parkinson’s disease and loss of cognitive ability in children.

                Side effects of omega-3 fatty acids

                • There are no extensive side effects of omega-3 fatty acid supplements, but it may cause gastrointestinal problems like diarrhea. However, it can be manageable by limiting the usage of supplements. 
                • People who are using any medication or drugs should consult with a doctor before using omega-3 supplements because it might affect their health.

                References

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                2. Libretexts. (2022, July 4). Introduction to fatty acids. Retrieved from https://chem.libretexts.org/Bookshelves/Biological_Chemistry/Supplemental_Modules_(Biological_Chemistry)/Lipids/Fatty_Acids/Introduction_to_Fatty_Acids
                3. Biology Dictionary. (2019, October 4). Fatty acids. Retrieved from https://biologydictionary.net/fatty-acids/
                4. McLaughlin, K., PhD. (2020, October 20). Cell membrane. Retrieved from https://biologydictionary.net/cell-membrane/
                5. Office of Dietary Supplements – Omega-3 fatty acids. (n.d.). Retrieved from https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/
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                8. Admin. (2023, February 22). Omega-3 fatty acid – Structure, types, sources, and benefits. Retrieved from https://byjus.com/chemistry/omega-3-fatty-acids/#structure-of-omega-3-fatty-acid
                9. Testbook. (2023, May 15). omega-3 Fatty Acid: Definition, Structure, Sources, Benefits, Uses, side effects, symptoms, and Importance. Retrieved from https://testbook.com/chemistry/omega-3-fatty-acids
                10. Structures of omega-3 fatty acids | DHA/EPE Omega-3 Institute. (n.d.). Retrieved from https://dhaomega3.org/overview/structures-of-omega-3-fatty-acids
                11. Ellulu, M. (2012, April 29). Omega 3 [Slide show]. Retrieved from https://www.slideshare.net/slideshow/omega-3-12737406/12737406
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                13. Ms, F. H. (2024, January 26). 12 foods that are very high in omega-3. Retrieved from https://www.healthline.com/nutrition/12-omega-3-rich-foods
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                About Author

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                Prativa Shrestha

                Prativa Shrestha is an enthusiastic person pursuing a master's degree in Food Microbiology from St. Xavier's College., Kathmandu. Currently, She is doing thesis work at Nepal Academy of Science and Technology (NAST). She loves to explore new ideas and showcase her creativity. She has also published two research articles. Moreover, She is interested in research fields like Food microbiology Biotechnology, and enzyme production.

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