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Unsaturated Fatty Acids: Omega-3, -5, -6, -7, -9

Dernière mise à jour : 14 mai 2020


Fatty acids are an important member of the lipids family. They are actually made up of long chains of hydrogen and carbon molecules (logically called hydrocarbon chains) with an acidic end called the carboxyl group (-COOH) and a methyl group at the other end (CH3) which is also referred to as the omega end of the fatty acid (figure 1).

The length of the hydrocarbon chain and the number and type of bonds it has determines the type of fatty acid it forms, how our body processes it and how healthy it is for us. Based on this information, fatty acids can be categorized into three general groups:


Fatty acids play various important roles in the body including:

  • They provide energy and act as efficient energy storage units

  • they insulate and protect the body

  • they transport the fat-soluble vitamins (A, D, E, K) and are a precursor of active vitamin D

  • They become part of cell membranes (as phospholipids)

  • They are a structural component in cells and lipoproteins

  • They are part of the structure of certain steroid hormones: estrogen and testosterone

  • They are involved in a wide range of biological signaling pathways


Unsaturated fatty acids are named according to a convention based on the location of their first double bond with respect to the omega end of the chain. Therefore, an omega-3 fatty acid has its first double bond located 3 carbon atoms away from the omega end and an omega-6 fatty acid has its first double bond located 6 carbons away from the omega end, and so on (figure 3).


Some fatty acids are considered essential because they are necessary for optimal health yet our bodies cannot synthesize them. We have to obtain them from our diet to avoid any deficiencies. The two essential fatty acids are alpha-linoleic acid (ALA) and linolenic acid (LA). Other fatty acids which are also very necessary for our health are considered non-essential because a healthy body can manufacture them if it receives enough ALA and LA from the diet.

However, even with adequate intake of both ALA and LA the conversion and/or synthesis of the non-essential fatty acids is not always very efficient. Therefore, in order to ensure that our body receives sufficient quantities of all the unsaturated fatty acids it needs and that an optimal ratio between the different fatty acids is maintained, it is important to include both essential and non-essential fatty acids in our diets and of course to also adopt healthy lifestyle habits:

  • A healthy diet rich in leafy green vegetables, avocados, raw seeds and nuts

  • Consumption of omega-rich fish at least 3-4 times per week (choose wild or organic fish that is low in mercury content).

  • Extra virgin olive oil for salad seasoning and cooking

  • Daily omega supplementation, when and as needed

The following table contains food sources of the different fatty acids and highlights the many important roles they play in maintaining good health.


Khan Academy: Overview of lipids, covering fats & oils, saturated & unsaturated fats, triglycerides, phospholipids, steroids.

Cooper GM, The Cell: A Molecular Approach. 2nd edition; Structure of the plasma membrane. Sunderland (MA): Sinauer Associates; 2000

Dr Ananya Manda, Lipid Biological Functions

Dr. Barry Sears: ‘’Omega Rx Zone’’; Regan Books, Harpertorch, HarperCollins Publishers 2002

SFGate: Three Functions of Fat in The Body

Gene Bruno; Essential & Non-Essential Fatty Acids. Huntington college of Health Sciences 2005: Literature Education Series On Dietary Supplements

Dr. Michael Roisen, MD : What should I know about odd omega fatty acids 3,5,7, and 9?

Authority Nutrition: What Are Omega-3 Fatty Acids? Explained in Human Terms

Chang CY, De DS, Chen JY. ‘’Essential Fatty Acids and Human Brain’’; Acta Neurol Taiwan 2009 Dec; 18(4)231-41

Joseph C. Maroon, M.D. and Jeffrey Bost, P.A.C. ‘’Fish Oil, The Natural Anti-Inflammatory’’. Basic Health Publications Inc. 2006

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