Vegetable oils sound healthy!

 ‘Vegetable oils are very unstable - that is, they can become dangerously rancid very quickly. Rancid means oxidised, and in your body, oxidised means damage to your cells and tissues. . . If you eat vegetable oils that are already oxidised from heat and light in processing, you are exposing your own healthy tissues to a volatile substance that will damage them.’ 

― Julia Ross

The heart foundation guidelines still promote the use of seed and vegetable oils and yet these oils are one of the worst things to come out of industrial agriculture.

Marketed as vegetable oils to appear healthy; these unstable, pro-inflammatory oils are present in nearly all of our processed foods and there is some evidence that the impact of vegetable oils on human health is worse that we could have imagined [i] One study published in Open Heart concluded that an increase in dietary linoleic acid from industrial seed oils promotes inflammation, and atherosclerosis. [ii] Although the research is inconclusive concerning health risks, there are no good randomised clinical trials to indicate that seed oils are good for cardiovascular health, or human health in general.

We were told that consuming vegetable oils (canola, sunflower, soybean, safflower, and palm oil), would reduce the risk of heart disease as there was evidence that they reduce cholesterol. We now know there is no association between cholesterol and heart disease and yet vegetable oils are still recommended over saturated fat.

 These oils are pro-inflammatory because they are omega 6 fatty acids, and omega 6 fatty acids tend to fuel our inflammatory pathways. Omega 3 fatty acids are anti-inflammatory and throughout history our diets were a ratio of 1:1 omega 6 to omega 3 fatty acids. This is ideal, but our modern diet is so saturated with omega 6 fatty acids that they have displaced omega 3 fatty acids, even reducing the availability of the anti-inflammatory omega 3 in our tissues.

David Gillespie, author of Toxic Oils proposes that when we start to replace omega 3 fats in our diets with fats that have been manufactured from seeds, we significantly increase the amount of  harmful omega 6 fats incorporated into our cell membranes. These fats’ are very prone to oxidation and oxidation leads inevitably down a pathway to inflammation and then to cancer and heart disease.

This notion is supported by a study published in Biochimica et Biophysica Acta (BBA) – Biomembranes, with the conclusion that diets containing less that 10 percent of omega 3 fatty acids as total polyunsaturated fatty acids has significant negative health effects and impacts membrane composition. [iii]

The estimated consumption of soybean oil has increased more than 1000 fold from 1909- 1999, resulting in declined omega 3 fatty acids in our tissues. [iv]  We know that our gut microbiome is integral to human health and influences all aspects of physical and mental health. [v] A recent study has reported that soybean oil disrupts our gut microbiome and is associated with increase of cardiovascular disease biomarkers. [vi]

‘These are the so-called “vegetable” oils many of us grew up on. Found at your typical grocery store, these clear, tasteless, highly refined and processed oils include corn, soybean, canola, safflower, and sunflower oils. ‘

-Dr. Mark Hyman

Dr. Cate Shanahan is a board certified family physician, trained in biochemistry and genetics at Cornell, attending Robert Wood Johnson Medical School, disagrees that seed oils are toxic because they contain a high concentration of omega 6 fatty acids. Rather she asserts they are toxic because the fats are oxidised. In her book the Fatburn Fix Shanahan suggests that industrially produced seed oils accumulate in our body fat. They then play havoc on our metabolism, and mood. We aren’t meant to burn omega 3 and omega 6 fatty acids as energy, rather they play an important role in cell membrane integrity and inflammatory processes. So what happens is we store these fatty acids in our adipose tissue and they stay there.

A 2015 study in the Advances in Nutrition review journal set out determine increases in omega 6 linoleic acid in adipose tissue in a US cohort.[vii] The researchers found that concentrations of linoleic acid has increased by a whopping 136 percent in adipose tissue between 1959 and 2008. In 2008 adipose tissue linoleic acid concentrations sat at 21.5 percent and this correlates with increased intake of omega 6 fatty acids.  We don’t know the full extent of the health impact of stored linoleic acid in our tissues; however it does impact biological processes via oxidation products.

 As far back as 2001, there have been suggestions that polyunsaturated seed oils when heated emit toxic compounds. These toxic compounds arising from heated seed oils are implicated in the development of atherosclerosis, rheumatoid arthritis, cancer and even birth defects.[viii] This is not the case when cooking with saturated or monounsaturated fats.

In modern western countries seed oils are packed into almost all commercially produced food; the amount of omega 6 fatty acids we consume has exploded. In Australia, the average polyunsaturated fat intake is currently at least 22 grams a day; more than double what it was in 1996.

Back In 1996, a study from the Karolinska Institute in Sweden including 63,870 women aged between 40 and 76 years monitored diet and breast cancer occurrence over 4.2 years. Saturated, monounsaturated and polyunsaturated fat intake was recorded. The results showed no association between total fat or saturated fat intake and risk of breast cancer. Higher intake of monounsaturated fat reduced the risk of breast cancer by 20 percent, but high consumption of polyunsaturated fat increased the risk by 20 percent. [ix] This had been demonstrated in rodent studies earlier. More recent research is starting to suggest that polyunsaturated fats, and in particular the omega-6 fats in seed oils is responsible for the accelerating incidence of diseases as diverse as macular degeneration, [x] as well as inflammatory conditions such as autoimmune disease,[xi] inflammatory bowel syndrome, [xii]and obesity. [xiii]

A recent study published in Scientific Reports shows that chronic exposure to canola oil for six months leads to increased body weight and neuro-inflammation, along with other markers of Alzheimer’s Disease in mice.[xiv] And we know that inflammation is central to an unwell mind, so high intake of seed oils will increase inflammation and contribute to poor mental health.[xv]

These oils are toxic but very cheap and are in most processed foods. We really need to take charge of our health and boycott restaurants and cafes which continue to use vegetable oils over more stable saturated fats.

[i] H Okuyama, PH Langsjoen, N Ohara et al. (2016). ‘Medicines and Vegetable Oils as Hidden Causes of Cardiovascular Disease and Diabetes.’ Pharmacology. Vol 98 pp134-170.

[ii] JJ DiNicolantonio, JH O’Keefe. (2018). ‘Omega-6 vegetable oils as a driver of coronary heart disease: the oxidized linoleic acid hypothesis.’Open Heart 2018;5:e000898. doi: 10.1136/openhrt-2018-000898

[iii] SK. Abbott, PL. Else, TA. Atkins et al (2012).’Fatty acid composition of membrane bilayers: Importance of diet polyunsaturated fat balance.’Biochimica et Biophysica Acta (BBA) – Biomembranes. Vol 1818 (5) pp 1309-1317.

[iv] TL Blasbalg, JR Hibbeln, CE Ramsden et al. (2011). ‘Changes in consumption of omega-3 and omega-6 fatty acids in the United States during the 20th century.’ American Journal of Clinical Nutrition. Vol 93(5) pp 950-962.

[v] AM Valdes, J Walter, E Segal et al (2018). ‘Role of the gut microbiota in nutrition and health.’ British Medical Journal. Vol 361 :k2179

[vi] H Korach-Rechtman, O Rom, L Mazouz et al (2020). ‘Soybean Oil Modulates the Gut Microbiota Associated with Atherogenic Biomarkers.’ Microorganisms. Vol 8(4) p 486.

[vii] SJ Guyenet , SE Carlson (2015). ‘Increase in adipose tissue linoleic acid of US adults in the last half century.’ Advances in nutrition (Bethesda, Md.). Vol  6(6) pp 660–664.

[viii] M Grootveld, CJ Silwood, P Addios et al (2001). ‘Health Effects Of Oxidised Heated Oils.  ’Foodservice Research International. Vol 13 pp 41-55. 

[ix] A Wolk, R Bergström, D Hunter et al (1998). ‘A prospective study of association of monounsaturated fat and other types of fat with risk of breast cancer.’ 

Archives of Internal Medicine. Vol 158 pp 41- 45.

[x] TC Mance, D Kovacević , Z Alpeza-Dunato et al (2011). ‘The role of omega6 to omega3 ratio in development and progression of age-related macular degeneration.’ Coll Antropol. Vol 35 (2) pp 307-310.

[xi] G Fernandes. ‘Dietary lipids and risk of autoimmune disease.’ Clinical Immunology and  Immunopathology. Vol 72(2) pp193-197.

[xii] G Clarke, P Fitzgerald, AA Hennessy et al (2010). ‘Marked elevations in pro-inflammatory polyunsaturated fatty acid metabolites in females with irritable bowel syndrome. ‘Journal of lipid research,. Vol 51(5) pp 1186–1192.

[xiii] MC Rudolph, BE Young, DJ Lemas et al. (2017). ‘Early infant adipose deposition is positively associated with the n-6 to n-3 fatty acid ratio in human milk independent of maternal BMI.’ International Journal of Obesity (Lond). Vol 41(4) pp 510-517.

[xiv] E Lauretti, D Praticò (2017). ‘Effect of canola oil consumption on memory, synapse and neuropathology in the triple transgenic mouse model of Alzheimer’s disease.’ Scientific  Reports. Vol 7 p17134

[xv] RK McNamara, FE Lotrich (2012). ‘Elevated immune-inflammatory signaling in mood disorders: a new therapeutic target?’ Expert review of neurotherapeutics Vol 12(9), pp 1143–1161.