Essential fatty acids, such as omega-3 and omega-6, are fatty acids that are polyunsaturated due to the multiple double bonds in their biochemical structure. As a fatty acid, they are basically a hydrocarbon chain with a carboxylic acid on one end and a methyl group on the other end. The methyl end of the chain is referred to as “omega”. Thus, omega-3 and omega-6 fatty acids got their names based on where the first double bond between two carbon molecules occurs from the methyl end of the hydrocarbon chain. This means omega-3 fatty acid is the essential fatty acid whose first double bond occurs between the third and the fourth carbon molecules whereas the omega-6 fatty acid is one in which the first double bond is between the sixth and the seventh carbon molecules.1, 2
Why essential fatty acids are essential
Essential fatty acids, particularly omega-3 and omega-6, are labeled as essential because we need them for various biological processes but our body is not equipped to produce them. We lack desaturase enzymes, which catalyze the insertion of double bonds distinctive of omega-3 and omega-6. We can only obtain these essential fatty acids by consuming food containing them. Some of the good sources are fish, seeds, bananas, nuts, and vegetable oils. In humans, α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are the three most notable omega-3 fatty acids whereas linoleic acid (LA) is one of the most important forms of omega-6 fatty acids.1, 2 However, how much of the essential fatty acids we need daily varies according to what our body requires. Our body needs them in an amount based on several confounding factors. Some of the factors to consider are physical activity and the time of the year.3
Biological importance of essential fatty acids omega-3 and omega-6
The essential fatty acids, omega-3 and omega-6, are important in the diet because of their various biological roles. The biochemical processes in which they take a part of are mostly associated with the regulation of the inflammatory responses of the body. For instance, they form the precursors to prostaglandins, thromboxane, leukotrienes, lipoxins, and resolvins. The essential fatty acids are also involved in cell signaling, e.g. by modulating lipid rafts in cell membranes. Furthermore, the essential fatty acids, and their metabolites, have been found to: (1) modulate the activities of angiotensin-converting and HMG-CoA reductase enzymes, (2) act as nitric oxide enhancers, (3) serve as β-blockers, (4) enhance diuresis, (5) enhance insulin action, (6) enhance insulin action, and (7) function as anti-atherosclerotic molecules.4
Essential fatty acids: the omega-6: omega-3 ratio
Too much of anything, no matter how good they are for health, can turn out bad. The essential fatty acids omega-3 and omega-6 can turn against us especially when taken in wrong proportions. They are unsaturated fats and therefore they are tagged as the healthy fats since they are “good for the heart”. Omega-3 fatty acids, most especially, have been associated with increasing high density lipoprotein (HDL, the good cholesterol) while decreasing low density lipoprotein (LDL, “the bad cholesterol”). However, a great disparity between the amount of omega-6 and omega-3 in the diet could be detrimental to health. Too much omega-6 while too little of omega-3 in the diet has been linked to increased risk to chronic inflammation and cancers such as breast, prostate, and colorectal. In contrast, more omega-3 fatty acids than omega-6 promoted anti-inflammation and decreased risk to cancer.3, 5
No consensus has been reached yet as to the proper omega-6: omega-3 fatty acid ratio. However, researchers recommend the ratio from 1:1 or 2:1 to 5:1 of omega-6 fatty acid to omega-3 fatty acid.5 More studies in this regard are needed. A healthy ratio of these essential fatty acids appears to be a key to proper biological functions and decreased risk to certain life-threatening health conditions.
— written by Maria Victoria Gonzaga
1 “Omega-3 fatty acid”. (n.d.). Biology-Online Dictionary. Retrieved from https://biology-online.org/dictionary/Omega-3_fatty_acid
2 “Omega-6 fatty acid”. (n.d.). Biology-Online Dictionary. Retrieved from https://biology-online.org/dictionary/Omega-6_fatty_acid
3 DiPasquale, D. (2011). “Everything About Fat”. Sott.net. Retrieved from https://www.sott.net/article/230686-Everything-About-Fat
4 Das, U. N. (2006). Biological significance of essential fatty acids. J Assoc Physicians India. 54:309-19. https://pdfs.semanticscholar.org/ff75/7e0dbe0a14fc2810ba52b833a5682b02b09e.pdf
5 Huerta-Yépez, S., Tirado-Rodriguez, A. B., & Hankinson, O. (2016). Role of diets rich in omega-3 and omega-6 in the development of cancer. Bol Med Hosp Infant Mex. 73(6):446-456. doi: 10.1016/j.bmhimx.2016.11.001.