Difference Between Omega 3 and Omega 6 Fatty Acids

Key Difference – Omega 3 vs Omega 6 Fatty Acids 


 

The fatty acids have two ends. They are the carboxylic acid (-COOH) end, which is known as the beginning of the chain and therefore also known as alpha, and the methyl (CH3) end, which is known as the tail of the chain and therefore also known as omega. The name of the fatty acid is determined by the position of the first double bond, calculated from the methyl end, which is the Omega (ω-) or the n-end. Healthy omega 3 fatty acids and omega 6 fatty acids are some of the most popular supplements on the pharmaceutical and nutraceuticals market. Typically they are derived from plant and fish oils. They are well investigated and relatively free from adverse side effects. Omega-3 fatty acids are polyunsaturated fatty acids and their final double bond (C=C) exists at the third carbon atom from the end of the carbon chain. Omega-6 fatty acids also are polyunsaturated fatty acids but, in contrast, their final double bond (C=C) exists at the sixth carbon atom from the end of the carbon chain or the methyl end. This is the key difference between omega 3 and omega 6 fatty acids, and this article explores all the difference chemical and physical properties between omega 3 and omega 6 fatty acids.

What are Omega 3 Fatty Acids?

Omega-3 fatty acids are polyunsaturated fatty acids (PUFAs) with a double bond (C=C) at the third carbon atom from the tail of the carbon chain. There are three types of omega-3 fatty acids involved in human physiology, and they are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Humans are unable to synthesize the required amount of omega-3 fatty acids in the body, but can gain the shorter chain omega-3 fatty acid, the α-linolenic acid (ALA), through daily diet and use it to produce the more important long-chain omega-3 fatty acids such as EPA and DHA. However, the ability to make the longer chain omega-3 fatty acids from ALA may be decreased with aging. When foods exposed to the atmosphere, omega 3 unsaturated fatty acids are susceptible to oxidation and rancidity.

Difference Between Omega 3 and Omega 6 Fatty Acids

Chemical structure of alpha-linolenic acid (ALA)

What are Omega 6 Fatty Acids?

Omega-6 fatty acids are polyunsaturated fatty acids (PUFAs) with a final double bond (C=C) at the sixth carbon atom from the tail of the carbon chain. They also belong to the family of pro-inflammatory and anti-inflammatory polyunsaturated fatty acids. Linoleic acid is the shortest chained omega−6 fatty acid, and it is one of many essential fatty acids because the human body cannot synthesize it. Four major food oils such as palm, soybean, rapeseed, and sunflower are rich sources of omega 6 fatty acids. The evening primrose flower (O. biennis) also produces oil containing a high content of γ-linolenic acid that is a type of omega−6 fatty acid.

Key Difference - Omega 3 vs Omega 6 Fatty Acids

Chemical structure of linoleic acid

What is the difference between Omega 3 and Omega 6 Fatty Acids?

Definition:

Omega 3 fatty acids are polyunsaturated fatty acids with a final double bond (C=C) at the third carbon atom from the tail of the carbon chain.

Omega 6 fatty acids are polyunsaturated fatty acids with a final double bond (C=C) at the sixth carbon atom from the tail of the carbon chain.

Other Names:

Omega 3 fatty acids: ω-3 fatty acids, n-3 fatty acids

Omega 6 fatty acids: ω-6 fatty acids, n-6 fatty acids

Chemical Structure:

Omega 3 fatty acids: ALA is an essential omega-3 fatty acid that denotes as 18:3Δ9c, 12c, and 15c. This means a chain of 18 carbons with 3 double bonds on carbons run to 9, 12, and 15. Although chemists count from the carbonyl carbon (indicate in blue numbering), biologists and nutritionist count from the n (ω) carbon (indicate in red numbering). From the n (ω) end (tail of the fatty acid), the first double bond appears as the third carbon-carbon bond, therefore, the name “n-3″ or Omega 3 fatty acid.

Omega 6 fatty acids: Linoleic acid is an essential omega-6 fatty acid that denotes as 18:2Δ9c, 12c. This means a chain of 18 carbons with 2 double bonds on carbons run to 9 and 12. Although chemists count from the carbonyl carbon (indicate in blue numbering), biologists and nutritionist count from the n (ω) carbon (indicate in red numbering). From the n (ω) end (tail of the fatty acid), the first double bond appears as the sixth carbon-carbon bond, therefore the name “n-6″ or Omega 6 fatty acid.

Most Common Examples:

Omega 3 fatty acids: α-Linolenic acid (ALA), Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA)

Omega 6 fatty acids: Linoleic acid (LA), Gamma-linolenic acid (GLA), Dihomo-gamma-linolenic acid (DGLA), Arachidonic acid (AA)

Essential Fatty Acids:

Omega 3 fatty acids: α-Linolenic acid (ALA)

Omega 6 fatty acids: Linoleic acid (LA)

Sources of Omega 3 and Omega 6 Fatty Acids:

Omega 3 fatty acids: α-linolenic acid (ALA) is found in plant oils such as walnut, edible seeds, clary sage seed oil, algal oil, flaxseed oil, Sacha Inchi oil, Echium oil, and hemp oil. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are both commonly found in marine oils, marine algae, phytoplankton, fish oil, krill oil, egg oil, and squid oil.

Omega 6 fatty acids: Rich in palm, soybean, rapeseed, evening primrose flower, cereal, and sunflower oils

Health Aspects:

Omega 3 fatty acids are associated with various health benefits. They are;

  • Reduce the risk of cancer development
  • Prevent cardiovascular disease, platelet aggregation and hypertension
  • Help to reduce LDL cholesterol (Bad cholesterol) and increase HDL cholesterol (good cholesterol)
  • They have the anti-inflammatory activity and lowers markers of inflammation in the blood such as C-reactive protein and interleukin 6
  • Reduce the risk of rheumatoid arthritis
  • Supplements are given to autism children and Alzheimer’s diseases patients
  • Brain development in small children

Omega 6 fatty acids: They have both pro-inflammatory and anti-inflammatory properties. They are incorporated into pharmaceutical drugs to inhibit the inflammatory process in atherosclerosis, asthma, arthritis, vascular disease, thrombosis, immune-inflammatory processes, and tumor proliferation. But excess omega−6 fatty acids consumption interfere with the health benefits of omega−3 fats because they compete for the equivalent rate to contact with limiting enzymes. In addition to that, a high quantity of omega−6 to omega−3 fat in the diet shifts the physiological state in the tissues in the direction of the pathogenesis of many diseases such as pro-thrombotic, pro-inflammatory and pro-constrictive.

In conclusion, both omega 3 and omega 6 fatty acids have several roles in the human body. In addition to being the principal component of stored fat, they also serve as important building blocks of cell membranes and regulate inflammatory processes.

 

References

Okuyama, H., Ichikawa, Y., Sun, Y., Hamazaki, T. and Lands, W.E.M. (2006).ω3 Fatty Acids Effectively Prevent Coronary Heart Disease and Other Late-Onset Diseases – The Excessive Linoleic Acid Syndrome. In Okuyama, H. Prevention of Coronary Heart Disease.World Review of Nutrition and Dietetics. pp. 83–103.

Ricciotti, Emanuela and FitzGerald, Garret, A. (2011). Prostaglandins and inflammation.American Heart Association Journal, 31(5): 986–1000.

Scorletti, E. and Byrne, C. D. (2013).Omega-3 fatty acids, hepatic lipid metabolism, and nonalcoholic fatty liver disease.Annual review of nutrition, 33(1): 231–48.

 

Image Courtesy:

1. ALA Numbering By Edgar181 [Public domain], via Wikimedia Commons

2. LA Numbering By Edgar181 at English Wikipedia [Public domain], via Wikimedia Commons