Omega-6 fatty acid

Omega-6 fatty acids (also referred to as ω-6 fatty acids or n-6 fatty acids) are a family of polyunsaturated fatty acids that have in common a final carbon-carbon double bond in the n-6 position, that is, the sixth bond, counting from the methyl end.[1]

The evening primrose flower (O. biennis) produces an oil containing a high content of γ-linolenic acid, a type of omega-6 fatty acid.

Health effectsEdit

One review found that an increased intake of omega‐6 fatty acids has been shown to reduce total serum cholesterol and may reduce myocardial infarction. The same review found no significant change in LDL cholesterol and triglycerides.[2] A 2021 review found that omega 6 supplements do not affect the risk of CVD morbidity and mortality.[3]

Dietary sourcesEdit

Dietary sources of omega-6 fatty acids include:[4]

Vegetable oilsEdit

Vegetable oils are a major source of omega-6 linoleic acid. Worldwide, more than 100 million metric tons of vegetable oils are extracted annually from palm fruits, soybean seeds, rape seeds, and sunflower seeds, providing more than 32 million metric tons of omega-6 linoleic acid and 4 million metric tons of omega-3 alpha-linolenic acid.[5][6]

Properties of vegetable oils[7][8]
Type Processing
treatment[9]
Saturated
fatty acids
Monounsaturated
fatty acids
Polyunsaturated
fatty acids
Smoke point
Total[7] Oleic
acid
(ω-9)
Total[7] α-Linolenic
acid
(ω-3)
Linoleic
acid
(ω-6)
ω-6:3
ratio
Avocado[10] 11.6 70.6 52–66[11] 13.5 1 12.5 12.5:1 250 °C (482 °F)[12]
Brazil nut[13] 24.8 32.7 31.3 42.0 0.1 41.9 419:1 208 °C (406 °F)[14]
Canola[15] 7.4 63.3 61.8 28.1 9.1 18.6 2:1 238 °C (460 °F)[14]
Coconut[16] 82.5 6.3 6 1.7 175 °C (347 °F)[14]
Corn[17] 12.9 27.6 27.3 54.7 1 58 58:1 232 °C (450 °F)[18]
Cottonseed[19] 25.9 17.8 19 51.9 1 54 54:1 216 °C (420 °F)[18]
Flaxseed/linseed[20] 9.0 18.4 18 67.8 53 13 0.2:1 107 °C (225 °F)
Grape seed   10.5 14.3 14.3   74.7 74.7 very high 216 °C (421 °F)[21]
Hemp seed[22] 7.0 9.0 9.0 82.0 22.0 54.0 2.5:1 166 °C (330 °F)[23]
Olive[24] 13.8 73.0 71.3 10.5 0.7 9.8 14:1 193 °C (380 °F)[14]
Palm[25] 49.3 37.0 40 9.3 0.2 9.1 45.5:1 235 °C (455 °F)
Peanut[26] 16.2 57.1 55.4 19.9 0.318 19.6 61.6:1 232 °C (450 °F)[18]
Rice bran oil 25 38.4 2.2 34.4[27] 15.6 232 °C (450 °F)[28]
High-oleic safflower oil[29] 7.5 75.2 75.2 12.8 0 12.8 very high 212 °C (414 °F)[14]
Sesame[30] ? 14.2 39.7 39.3 41.7 0.3 41.3 138:1
Soybean[31] partially hydrogenated 14.9 43.0 42.5 37.6 2.6 34.9 13.4:1
Soybean[32] 15.6 22.8 22.6 57.7 7 51 7.3:1 238 °C (460 °F)[18]
Walnut oil[33] unrefined 9.1 22.8 22.2 63.3 10.4 52.9 5:1 160 °C (320 °F)[34]
Sunflower[35] 8.99 63.4 62.9 20.7 0.16 20.5 128:1 227 °C (440 °F)[18]
Cottonseed[36] hydrogenated 93.6 1.5 0.6 0.2 0.3 1.5:1
Palm[37] hydrogenated 88.2 5.7 0
The nutritional values are expressed as percent (%) by mass of total fat.

List of omega-6 fatty acidsEdit

 
The chemical structure of linoleic acid, a common omega-6 fatty acid found in many nuts, seeds, and vegetable oils.
Common name Lipid name Chemical name
Linoleic acid (LA) 18:2 (n−6) all-cis-9,12-octadecadienoic acid
Gamma-linolenic acid (GLA) 18:3 (n−6) all-cis-6,9,12-octadecatrienoic acid
Calendic acid 18:3 (n−6) 8E,10E,12Z-octadecatrienoic acid
Eicosadienoic acid 20:2 (n−6) all-cis-11,14-eicosadienoic acid
Dihomo-gamma-linolenic acid (DGLA) 20:3 (n−6) all-cis-8,11,14-eicosatrienoic acid
Arachidonic acid (AA, ARA) 20:4 (n−6) all-cis-5,8,11,14-eicosatetraenoic acid
Docosadienoic acid 22:2 (n−6) all-cis-13,16-docosadienoic acid
Adrenic acid 22:4 (n−6) all-cis-7,10,13,16-docosatetraenoic acid
Osbond acid 22:5 (n−6) all-cis-4,7,10,13,16-docosapentaenoic acid
Tetracosatetraenoic acid 24:4 (n−6) all-cis-9,12,15,18-tetracosatetraenoic acid
Tetracosapentaenoic acid 24:5 (n−6) all-cis-6,9,12,15,18-tetracosapentaenoic acid

The melting point of the fatty acids increases as the number of carbons in the chain increases.[38]

See alsoEdit

ReferencesEdit

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  2. ^ Hooper L, Al‐Khudairy L, Abdelhamid AS, Rees K, Brainard JS, Brown TJ, Ajabnoor SM, O'Brien AT, Winstanley LE, Donaldson DH, Song F, Deane KHO (2018). "Omega‐6 fats for the primary and secondary prevention of cardiovascular disease". Cochrane Database of Systematic Reviews. 11 (CD011094): CD011094. doi:10.1002/14651858.CD011094.pub4. PMC 6516799. PMID 30488422.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Mazidi, M., Shekoohi, N., Katsiki, N., & Banach, M. (2021). "Omega-6 fatty acids and the risk of cardiovascular disease: insights from a systematic review and meta-analysis of randomized controlled trials and a Mendelian randomization study". Archives of Medical Science. 18 (2): 466–479. doi:10.5114/aoms/136070. PMC 8924827. PMID 35316920.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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  17. ^ "Corn oil, industrial and retail, all purpose salad or cooking, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  18. ^ a b c d e Wolke, Robert L. (May 16, 2007). "Where There's Smoke, There's a Fryer". The Washington Post. Retrieved March 5, 2011.
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  20. ^ "Linseed/Flaxseed oil, cold pressed, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  21. ^ Garavaglia J, Markoski MM, Oliveira A, Marcadenti A (2016). "Grape Seed Oil Compounds: Biological and Chemical Actions for Health". Nutrition and Metabolic Insights. 9: 59–64. doi:10.4137/NMI.S32910. PMC 4988453. PMID 27559299.
  22. ^ Callaway J, Schwab U, Harvima I, Halonen P, Mykkänen O, Hyvönen P, Järvinen T (April 2005). "Efficacy of dietary hempseed oil in patients with atopic dermatitis". The Journal of Dermatological Treatment. 16 (2): 87–94. doi:10.1080/09546630510035832. PMID 16019622. S2CID 18445488.
  23. ^ "Smoke points of oils" (PDF).
  24. ^ "Olive oil, salad or cooking, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  25. ^ "Palm oil, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  26. ^ "FoodData Central". fdc.nal.usda.gov.
  27. ^ Orthoefer, F. T. (2005). "Chapter 10: Rice Bran Oil". In Shahidi, F. (ed.). Bailey's Industrial Oil and Fat Products. Vol. 2 (6 ed.). John Wiley & Sons, Inc. p. 465. doi:10.1002/047167849X. ISBN 978-0-471-38552-3.
  28. ^ "Rice bran oil". RITO Partnership. Retrieved 22 January 2021.
  29. ^ "Safflower oil, salad or cooking, high oleic, primary commerce, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  30. ^ "Oil, sesame, salad or cooking". FoodData Central. fdc.nal.usda.gov.
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  32. ^ "Soybean oil, salad or cooking, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  33. ^ "Walnut oil, fat composition, 100 g". US National Nutrient Database, United States Department of Agriculture.
  34. ^ "Smoke Point of Oils". Baseline of Health. Jonbarron.org.
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BibliographyEdit