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 effects edit

The American Heart Association "supports an omega-6 PUFA intake of at least 5% to 10% of energy in the context of other AHA lifestyle and dietary recommendations. To reduce omega-6 PUFA intakes from their current levels would be more likely to increase than to decrease risk for coronary heart disease."[2]

A 2018 review found that an increased intake of omega‐6 fatty acids has been shown to reduce total serum cholesterol and may reduce myocardial infarction (heart attack), but found no significant change in LDL cholesterol and triglycerides.[3] A 2021 review found that omega-6 supplements do not affect the risk of CVD morbidity and mortality.[4]

A 2023 review found that omega-6 polyunsaturated fatty acids are associated with lower risk of high blood pressure.[5] Omega‐6 fatty acids are not associated with atrial fibrillation.[6]

Dietary sources edit

Dietary sources of omega-6 fatty acids include:[7]

Vegetable oils edit

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, grape 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.[8][9]

Properties of vegetable oils[10][11]
The nutritional values are expressed as percent (%) by mass of total fat.
Type Processing
treatment[12]
Saturated
fatty acids
Monounsaturated
fatty acids
Polyunsaturated
fatty acids
Smoke point
Total[10] Oleic
acid
(ω-9)
Total[10] α-Linolenic
acid
(ω-3)
Linoleic
acid
(ω-6)
ω-6:3
ratio
Avocado[13] 11.6 70.6 52–66
[14]
13.5 1 12.5 12.5:1 250 °C (482 °F)[15]
Brazil nut[16] 24.8 32.7 31.3 42.0 0.1 41.9 419:1 208 °C (406 °F)[17]
Canola[18] 7.4 63.3 61.8 28.1 9.1 18.6 2:1 204 °C (400 °F)[19]
Coconut[20] 82.5 6.3 6 1.7 175 °C (347 °F)[17]
Corn[21] 12.9 27.6 27.3 54.7 1 58 58:1 232 °C (450 °F)[19]
Cottonseed[22] 25.9 17.8 19 51.9 1 54 54:1 216 °C (420 °F)[19]
Cottonseed[23] hydrogenated 93.6 1.5 0.6 0.2 0.3 1.5:1
Flaxseed/linseed[24] 9.0 18.4 18 67.8 53 13 0.2:1 107 °C (225 °F)
Grape seed   10.4 14.8 14.3   74.9 0.15 74.7 very high 216 °C (421 °F)[25]
Hemp seed[26] 7.0 9.0 9.0 82.0 22.0 54.0 2.5:1 166 °C (330 °F)[27]
High-oleic safflower oil[28] 7.5 75.2 75.2 12.8 0 12.8 very high 212 °C (414 °F)[17]
Olive, Extra Virgin[29] 13.8 73.0 71.3 10.5 0.7 9.8 14:1 193 °C (380 °F)[17]
Palm[30] 49.3 37.0 40 9.3 0.2 9.1 45.5:1 235 °C (455 °F)
Palm[31] hydrogenated 88.2 5.7 0
Peanut[32] 16.2 57.1 55.4 19.9 0.318 19.6 61.6:1 232 °C (450 °F)[19]
Rice bran oil 25 38.4 38.4 36.6 2.2 34.4[33] 15.6:1 232 °C (450 °F)[34]
Sesame[35] 14.2 39.7 39.3 41.7 0.3 41.3 138:1
Soybean[36] 15.6 22.8 22.6 57.7 7 51 7.3:1 238 °C (460 °F)[19]
Soybean[37] partially hydrogenated 14.9 43.0 42.5 37.6 2.6 34.9 13.4:1
Sunflower[38] 8.99 63.4 62.9 20.7 0.16 20.5 128:1 227 °C (440 °F)[19]
Walnut oil[39] unrefined 9.1 22.8 22.2 63.3 10.4 52.9 5:1 160 °C (320 °F)[40]
 
Comparison of dietary fat composition from a 1995 study

List of omega-6 fatty acids edit

 
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.[41]

See also edit

References edit

  1. ^ Chow, Ching Kuang (2001). Fatty Acids in Foods and Their Health Implications. New York: Routledge Publishing. OCLC 25508943.[page needed]
  2. ^ Harris, WS; Mozaffarian, D; Rimm, E; Kris-Etherton, P; Rudel, LL; Appel, LJ; Engler, MM; Engler, MB; Sacks, F (2009). "Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention". Circulation. 119 (6): 902–7. doi:10.1161/CIRCULATIONAHA.108.191627. PMID 19171857.
  3. ^ 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 KH (2018). "Omega‐6 fats for the primary and secondary prevention of cardiovascular disease". Cochrane Database of Systematic Reviews. 11. CD011094. doi:10.1002/14651858.CD011094.pub4. PMC 6516799. PMID 30488422.
  4. ^ 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.
  5. ^ Hajihashemi P, Feizi A, Heidari Z, Haghighatdoost F. (2023). "Association of omega-6 polyunsaturated fatty acids with blood pressure: A systematic review and meta-analysis of observational studies". Critical Reviews in Food Science and Nutrition. 63 (14): 2247–2259. doi:10.1080/10408398.2021.1973364. PMID 36939291.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ Garg PK, Guan W, Nomura S, Weir NL, Tintle N, Virtanen JK, Hirakawa Y, Qian F, Sun Q, Rimm E, Lemaitre RN, Jensen PN, Heckbert SR, Imamura F, Steur M, Leander K, Laguzzi F, Voortman T, Ninomiya T, Mozaffarian D, Harris WS, Siscovick DS, Tsai MY (2023). "Fatty Acids and Outcomes Research Consortium (FORCE). n-6 fatty acid biomarkers and incident atrial fibrillation: an individual participant-level pooled analysis of 11 international prospective studies". The American Journal of Clinical Nutrition. 118 (5): 921–929. doi:10.1016/j.ajcnut.2023.09.008. PMID 37769813.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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  12. ^ "USDA Specifications for Vegetable Oil Margarine Effective August 28, 1996" (PDF).
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  20. ^ "Coconut oil, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  21. ^ "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.
  22. ^ "Cottonseed 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.
  23. ^ "Cottonseed oil, industrial, fully hydrogenated, fat composition, 100 g". US National Nutrient Database, Release 28, United States Department of Agriculture. May 2016. Retrieved 6 September 2017.
  24. ^ "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.
  25. ^ 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.
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  29. ^ "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.
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  33. ^ Orthoefer FT (2005). "Chapter 10: Rice Bran Oil". In Shahidi F (ed.). Bailey's Industrial Oil and Fat Products. Vol. 2 (6th ed.). John Wiley & Sons, Inc. p. 465. doi:10.1002/047167849X. ISBN 978-0-471-38552-3.
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Bibliography edit