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]
Health effects
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
Dietary sources of omega-6 fatty acids include:[7]
Vegetable oils
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]
| 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 | 0.019 | 1.68 | 88:1 | 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] |
List of omega-6 fatty acids
| 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
References
Bibliography
- Tokar, Steve (2005-09-02). "Omega-6 fatty acids cause prostate tumor cell growth in culture". Medical News Today. MediLexicon International. Retrieved 2008-03-23.
- "Brain fatty acid levels linked to depression". News-Medical.Net. AZoNetwork. 2005-05-25. Retrieved 2008-03-23.
- Tribole, E.F. (2006-03-27). "Excess Omega-6 Fats Thwart Health Benefits from Omega-3 Fats". British Medical Journal Rapid Responses to Hooper, et Al., 2006. 332 (7544): 752. Retrieved 2008-03-23.
- Erasmus, Udo (1993). Fats That Heal, Fats That Kill (3rd ed.). Burnaby (BC): Alive Books. ISBN 978-0-920470-38-1.