Vegetables are good for us, right? But vegetable oils… Well, I’m no longer sure about them!
Most people perceive vegetable oils as natural and healthy. It must be the word ‘vegetable’ in them that has been contributing to their misperception for such a long time!
We can eat vegetables to our heart’s content, but vegetable oils must be curbed in our diets as soon as possible. Although the mainstream nutritionists recommend that we consume these oils because unsaturated fats are much healthier than saturated fats, many studies have now demonstrated that they can do serious harm.
The composition of the fatty acids in vegetable oils is different than anything we were ever exposed to throughout our evolution, which leads to physiological changes within our bodies and contributes to multiple diseases.
Here are 10 reasons why vegetable oils are causing concerns:
Vegetable oils are extremely high in Omega-6 linoleic acid
Omega-3 and Omega-6 fatty acids are polyunsaturated fats, meaning that they have many double bonds in their chemical structure. They are often termed ‘essential fatty acids’ because the body lacks the enzymes to produce them. These fatty acids are important for many biochemical pathways, including those related to inflammation, immunity and blood clotting.
We need to take a balanced amount of Omega-3 and Omega-6. When this balance goes off, it can interrupt these important biochemical pathways. For example, these 2 types of fatty acids often compete for the same enzymes and the same spots in cell membranes. They often have related but opposing roles: both of them are used to produce signaling molecules called eicosanoids. Eicosanoids made from Omega-6s tend to be pro-inflammatory, while those made from Omega-3s tend to be anti-inflammatory.
Throughout the human evolution, we used to consume balanced amounts of Omega-3 and Omega-6 fatty acids. The problem today is that this Omega-3 and Omega-6 balance is drastically slanted towards Omega-6. Not only are people eating way too much Omega-6, but also their Omega-3 intake is incredibly low, which is a genetic blueprint for disaster.
Whereas in the distant past our Omega-6 /Omega-3 ratio may have been about 1:1or 3:1, these days it is about 16:1! Way outside the evolutionary norms! Where then lies the rub?
Well, vegetable oils are by far the biggest source of Omega-6 fatty acids in the diet. They are particularly high in the Omega-6 fatty acid called linoleic acid.
So, it is the linoleic acid that causes a host of problems when consumed in excessive amounts, especially when Omega-3 intake is low (which is usually the case).
Linoleic acid builds up in cell membranes!
Fats are more than just sources of energy. Some of them have potent biological activity, and some remain in the body where they are used for structural and/or functional purposes. It turns out that linoleic acid, which is the main fatty acid in vegetable oils, does accumulate in the fat cells of the body, as well as in cell membranes.
So, our excessive consumption of vegetable oils leads to actual structural changes within our body’s tissues. The linoleic acid content of breast milk has also increased significantly!
- Consuming linoleic acid increases oxidative stress and contributes to endothelial dysfunction
Since polyunsaturated fats like linoleic acid have 2 or more double bonds in their chemical structure, it makes them sensitive to damage by free radicals-highly reactive molecules that are constantly being formed in the body. This is actually what antioxidants are for: they help neutralize the free radicals. When free radicals in the body outnumber the antioxidants, this leads to a condition known as oxidative stress.
Not surprisingly, because polyunsaturated fats are more disposed to damage by free radicals, studies have shown that a high intake of linoleic acid can contribute to oxidative stress. In one controlled trial, people were fed a diet high in Omega-6 linoleic acid, mostly from sunflower oil. After 4 weeks, blood markers of oxidative stress had increased significantly. Another thing they noted was that blood markers of Nitric Oxide (NO) levels had gone down.
Nitric oxide is a signaling molecule produced by the endothelium – the thin layer of cells that lines the vascular system. It helps dilate blood vessels and keep blood pressure down. Reduced nitric oxide is the first phase of endothelial dysfunction, where the lining of the vascular system stops working as it is supposed to.
To recap, linoleic acid from vegetable oils increases oxidative stress in the body, contributing to a state called endothelial dysfunction, which is a stepping stone towards heart disease and vascular problems.
Vegetable oils lower LDL levels, but they also lower HDL
One of the main reasons vegetable oils are mistakenly considered very healthy, is that consuming them can lower Total and LDL cholesterol levels. As most people know, LDL is often referred to as the “bad” cholesterol. Copious studies show that vegetable oils can lower LDL, which, when it is high, is considered a well-established risk factor for heart disease. However, it’s important to keep in mind that this is just a risk factor, it is not an actual diagnosed disease.
Vegetable oils have also been shown to mildly lower HDL levels, which is a bad thing because having a high HDL is associated with a low risk of heart disease.
To recap, it is true that vegetable oils can lower Total and LDL cholesterol levels. However, they can also lower HDL, the “good” cholesterol.
Vegetable oils increase oxidized LDL lipoproteins
What people refer to as “LDL cholesterol” isn’t really cholesterol. LDL stands for Low Density Lipoprotein – which is the protein that carries cholesterol in the bloodstream. One of the crucial steps in the heart disease process, is Low Density Lipoprotein becoming oxidized, forming what are called oxidized LDL particles, or ox-LDL. These are the LDL particles that build up inside the walls of the arteries.
Polyunsaturated fats from vegetable oils do find their way to LDL lipoproteins, making them much more likely to become oxidized and form ox-LDL particles.
To recap, vegetable oils do increase the susceptibility of LDL lipoproteins to oxidation, a crucial step in the development of heart disease. Heart disease is the world’s most common cause of death.