Over the course of a few decades, the consumption of vegetable oils has drastically increased thanks to modern industrial processing. This has coincided with the rise in nearly all chronic degenerative diseases, and for good reason1.
Previous to this increase in vegetable oil consumption, humans used animal based fats for cooking, such as lard or butter, or other traditional plant based oils like olive oil and coconut oil. Unfortunately, in the early days of nutritional research in the 1950’s, saturated fat was wrongly accused of increasing cholesterol and causing cardiovascular disease2. This lead to a switch from these healthy fats to highly processed vegetable oils like canola, corn, soy, etc. (which are also much cheaper to produce). In order to make these oils more stable and solid, they were hydrogenated, meaning they added hydrogen, which created trans fats. Many people today are aware that trans fats are extremely unhealthy and most countries have banned the use of them in food production. Although we have since stopped using hydrogenated vegetable oils (for the most part), the original vegetable oils are still problematic. These oils are typically high in omega-6 fats, a type of polyunsaturated fatty acid.
These fats are extremely sensitive to environmental change like temperature and UV exposure. When exposed to this they easily oxidise (chemical structure changes) and become toxic3. This is particularly unsettling as most vegetable oils are used for deep frying. Although omega-6 is not innately problematic (in fact it is important for many cellular functions), the processing and heating of it change the conversation. The other issue is that of the balance between omega-3 and omega-6 fats. When the ratio of omega-6 to omega-3 fats is significantly increased, it can lead to a plethora of health problems. Unfortunately, with today’s modern foods and cooking methods, our diets are significantly higher in omega-6’s and lower in omega-3’s – some estimates to the order of 20:1 (whereas it should be 1:1 to 3:1)1.
This imbalance leads to improper cellular signalling and increased levels of inflammation. Chronic inflammation leads to many known chronic degenerative diseases such cardiovascular disease, cancer, autoimmunity, arthritis and even psychological disorders. This inflammation also depletes the body of its natural antioxidants, which are important for managing the numerous sources of cellular stress (oxidation) – which is much more elevated in today’s high stress, toxin filled environments. Many of the top health experts place vegetable oils at the top of the list for most damaging foods to health. Unfortunately, almost all processed foods contain them and most restaurants still cook with them.
The best way to avoid these unhealthy fats is to stay away from premade foods, try not to eat out often, and cook your own food in high quality stable fats like butter, ghee, lard or coconut oil (olive oil is ok at medium heats).
- Hibbeln JR, Nieminen LRG, Blasbalg TL, Riggs JA, Lands WEM. Healthy Intakes of N-3 and N-6 Fatty Acids: Estimation Considering Worldwide Diversity. American Journal of Clinical Nutrition. 2006: 83(6);1483-93
- Nettleton JA, Brouwer IA, Geleijnse JM, Hornstra G. Saturated Fat Consumption and Risk of Coronary Heart Disease and Ischemic Stroke: A Science Update. Annals of Nutrition and Metabolism 2017:26–33
- Narasimhamurthy K, Raina RL. Long Term Feeding Effects of Heated and Friend Oils on Lipids and Lipoproteins in Rats. 1999:195(1);143-53