Read on to find out.
What are omega-6 fatty acids?
Omega-6 fatty acids are a type of polyunsaturated fat. They have a different chemical structure to saturated and monounsaturated fats by having at least two carbon-carbon double bonds, the first being at the 6th carbon from the methyl end. The main omega-6 fatty acid we consume is linoleic acid (Harris et al 2009; Paddock 2018). It is an essential fatty acid which cannot be made by the body and must be provided by the diet (Simopoulos 2016). It is from linoleic acid that other omega-6 fatty acids are made in the body (Russo 2008).
Where do we find it?
Rich sources of omega-6 fatty acids include vegetable oils such as corn, cotton seed, soybean, sunflower and safflower. Cold-pressed (unrefined) oils rather than refined are the best choice. No heat has been used during processing with the former which minimises unfavourable changes to the fat molecules (Cold Pressed oil Vs. Refined oil 2017). Brazil nuts, walnuts, sunflower seeds, hemp seed, and pumpkin seeds are also good sources (No need to avoid healthy omega-6 fats 2019; Robertson 2017; Russo 2008).
Why the controversy?
Omega-6 has often been seen in a negative light. Linoleic acid is the precursor to other long-chain omega-6 fatty acids including arachidonic acid. Like linoleic acid, it contributes to the makeup of the cell membrane, allowing fluidity and flexibility which is essential for the function of all cells (Tallima & El Ridi 2018; Wijendran & Hayes 2004). The focus however has been on the ability of arachidonic acid to produce pro-inflammatory substances. Coronary heart disease has an inflammatory component, which would suggest that a high dietary intake of omega-6 fatty acids would therefore increase the risk of coronary heart disease (Harris et al 2009).
Studies recently though claim to suggest otherwise. An analysis of 30 cohort studies in 2019 concluded that higher levels of circulating and tissue levels of linoleic acid (and maybe arachidonic acid) were not associated with an increased risk of cardiovascular events. Linoleic acid may also have a positive role in the prevention of cardiovascular disease. It seems the conversion rate of linoleic acid to arachidonic acid is low in the body. Furthermore, arachidonic acid is metabolically regulated irrespective of dietary intakes of linoleic acid (Marklund et al 2019).
Another recent study, via an analysis of 20 cohort studies, focussed on a possible connection between the omega-6 fatty acids, linoleic and arachidonic, and the prevention of type 2 diabetes. The authors’ findings claim that linoleic acid may be of benefit in the long-term prevention of type 2 diabetes and arachidonic acid is not harmful (Wu et al 2017).
Take home message:
Eat your omega-6 fatty acids from whole foods like nuts and seeds. Choose cold-pressed vegetable oils rather than refined. Always do your research so you can make informed food choices.
This column is not intended as medical advice but rather to provide information for educational purposes. Consult with your GP or other medical professional regarding the applicability of any of the information provided.
Cold Pressed Oil Vs. Refined Oil, 2017, Harappa Cold Pressed Oil, viewed 19 February 2020, <https://harappaoil.com/cold-pressed-oil-vs-refined-oil-why-you-should-not-use-refined-oils/>.
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, Circulation, Vol. 119, pp. 902-907.
Marklund, M et al, 2019, Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality, Circulation, Vol. 139, pp. 2422-2436.
No need to avoid healthy omega-6 fats 2019, Harvard Health Publishing, viewed 18 February 2020, < https://www.health.harvard.edu/newsletter_article/no-need-to-avoid-healthy-omega-6-fats>.
Paddock, C 2018, Could omega-6 fatty acids help us live longer? viewed 18 February 2020, < https://www.medicalnewstoday.com/articles/321266>.
Robertson, R 2017, Omega-3-6-9 Fatty Acids: A Complete Overview, viewed 18 February 2020, < https://www.healthline.com/nutrition/omega-3-6-9-overview>.
Simopoulos, AP, 2016 An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity, Nutrients, Vol. 8, 128.
Tallima, H & El Ridi, 2018, Arachidonic acid: Physiological roles and potential health benefits – A review, Journal of Advanced Research, Vol. 11, pp. 33-41.
Wijendran, V & Hayes, KC, 2004, DIETARY n-6 AND n-3 FATTY ACID BALANCE AND CARDIOVASCULAR HEALTH, Annual Reviews Nutrition, Vol. 24, pp. 597-615.
Wu, JHY et al, 2017, Omega-6 fatty acid biomarkers and incident type 2 diabetes: pooled analysis of individual-level data for 39 740 adults from 20 prospective cohort studies, The Lancet Diabetes & Endocrinology, Vol. 5, pp. 965-974.