For several years now, a real debate has been raging in the world of nutrition: are vegetable oils harmful to our health?
Some blame them for chronic inflammation and many modern diseases. Others consider them beneficial for the heart, highlighting their ability to reduce cholesterol and the risk of cardiovascular disease.
But where does the truth lie? Is the problem the nature of these oils or their excessive consumption? Or both?
Let’s decipher this subject together to better understand their impact on our health and make informed choices.
What are vegetable oils?
Vegetable oils are extracted from an oilseed plant, that is, a plant whose seeds, nuts, almonds or fruits contain lipids. Some examples:
- Rapeseed oil
- Corn oil
- Soybean oil
- Sunflower oil
- Grapeseed oil
- Rice bran oil
How are they produced?
These oils are extracted using industrial processes involving high heat, pressure and chemical solvents such as hexane (from petroleum). While most of the hexane is removed at the end of production, traces may remain.
Although these methods are effective in producing low-cost oils with a long shelf life, they can also oxidize the oils and generate potentially inflammatory byproducts.
Omega-6 vs. Omega-3: The Essential Balance
Seed oils are rich in unsaturated fatty acids, especially omega-6 , but contain little omega-3 . However, these two types of fats must exist in balance in our diet.
Omega-6s contribute to the body's inflammatory response, which is helpful in cases of infection or injury. Omega-3s have anti-inflammatory effects that benefit the brain, heart and cells.
But when omega-6s are consumed in excess, they take over and reduce the body's ability to use omega-3s. The result? Chronic, low-grade inflammation, which is associated with many diseases:
- Cardiovascular diseases
- Diabetes
- Depression and cognitive decline
- Arthritis and inflammatory pain
- Obesity
Historically, our ancestors had an omega-6 to omega-3 ratio of around 1:1 to 4:1. Today, with the overconsumption of seed oils, this ratio often reaches 10:1 or even 20:1.
Overconsumption: The Real Problem
The problem with vegetable oils is not only their composition, but above all their massive and unconscious consumption .
They are omnipresent in ultra-processed foods: chips, ready meals, industrial sauces, fast food... Between 1909 and 1999, the consumption of linoleic acid (from industrial oils) increased by more than 1,000% .
Even adding omega-3s to the diet is not enough if omega-6s remain excessive. Reducing vegetable oils and avoiding ultra-processed products is therefore essential .
Why Do Some People Promote Seed Oils?
Organizations such as the WHO recommend vegetable oils as a replacement for saturated fats. Their main argument? The polyunsaturated fatty acids (PUFAs) they contain help reduce LDL cholesterol.
However, monounsaturated fatty acids (MUFAs) found in olive or avocado oil provide the same benefits without the excess omega-6 .
In addition, PUFAs are very sensitive to heat. During cooking, they oxidize and form toxic by-products (aldehydes, lipid peroxides, OXLAMs) that are potentially inflammatory.
What to do?
Personally, I avoid seed oils and recommend replacing them with healthier alternatives:
For high temperature cooking : avocado oil, ghee, coconut oil
For moderate cooking : avocado oil, extra virgin olive oil
For seasonings : extra virgin olive oil, walnut oil, flaxseed oil
