Deep-fried foods are one of the worst foods you can eat. They are a major contributor to Alzheimer’s disease, type 2 diabetes and obesity. But the surprising thing is that until recently, researchers didn’t understand why. New theories point to vegetable and seed oils, which are rich in omega-6, polyunsaturated fatty acids. Could it be that omega-6s are responsible for the underlying mechanisms that lead to chronic disease?
Over the years on the Miracle Noodle blog, several articles have focused on the health risks of cooking with vegetable oils (like this one). Why another one? Well, there are two reasons.
First, it’s a very important topic to address simply for the fact that many people still believe that vegetable oils are healthy. And why wouldn’t people believe this? After all, vegetables are healthy. So vegetable oil must be healthy as well. Case in point: I used to go to a Mexican restaurant that prominently displayed a sign reading, “We proudly use vegetable oil instead of lard.”
Another reason why many people would be surprised to hear vegetable oil is unhealthy is that it contains omega-6 fatty acids, which is a polyunsaturated fatty acid. For over half a century, people have been programmed to believe that only saturated fat is bad for health.
The other reason to cover this topic is that up until recently, the exact mechanisms of how vegetable oils contributed to lifestyle diseases wasn’t understood.But in 2020, Japanese researchers, writing in Advances in Nutrition, explained the metabolic damage caused to cells by vegetable oils.
Omega 3 to Omega 6 Ratio
We’ll get to that research shortly. But first, it’s important to mention that omega-6 fatty acids aren’t inherently bad. In fact, they are essential fatty acids, which means you need them in your diet.The problem is that most westerners eat far too many foods with omega-6 fatty acids and not enough omega-3 fatty acids. Highly-processed foods are loaded with vegetable oils in order to extend the shelf life. Vegetable oils are predominantly omega-6 polyunsaturated fats. So if you’re eating lots of packaged foods, you’re consuming lots of omega 6’s.
Nutrition experts suggest eating a diet with a ratio of no higher than 4:1 omega 3 to omega 6 fatty acids. The problem with this suggestion is that when we eat meals, it’s really difficult to gauge how many grams of omega 3’s and 6’s you’re getting. Unlike counting carbs with an app, omega-6 counting isn’t as user friendly.
Because of the prevalence of processed foods in the western diet, most people are consuming up to 20 times the amount of omega-6s to omega-3s. The overconsumption of omega-6 fatty acids in vegetable oils has greatly contributed to inflammatory diseases.
Now let’s see what’s going on with the damage that vegetable oils cause at the molecular level…
How Omega 6 Fatty Acids Cause Cellular Death
What do canola oil, soybean oil, sunflower oil, and corn oil have in common? According to the Japanese researchers, they already contain or generate lipid peroxidation. What is lipid peroxidation? Lipid peroxidation is a chain of reactions. Free radicals "steal" electrons from the fatty substances (lipids) in cell membranes. This results in cellular damage.
Mild cellular damage can be overcome with DNA repair. But when your cells are constantly being bombarded by free radicals, premature aging is the result.
Vegetable Oils Are A “Shock” To The System
In addition to damaging lipids in the cell membranes, omega-6 fatty acids in vegetable oil also denature important proteins called heat-shock proteins. Heat shock proteins are a group of stress proteins that protect essential cell components from various types of harmful damage, Science Direct explains.
This damage to heat shock protein results in the inability of cells to recycle damaged proteins. Also, your cells have a digestive system of its own and it can be found in the part of the cell called the lysosome.
The shock to heat shock protein leads to instability of the lysosome. In other words, eating lots of processed food or cooking with lots of vegetable oil at home can not only adversely affect your digestive system, it can also interfere with digestion at the cellular level.
The Japanese researchers claimed that they were the first to show how the daily consumption of omega 6 polyunsaturated-rich vegetable oils causes the failure to repair lysosomes, ultimately leading to cellular death.
Vegetable Oils & Alzheimer’s Disease
In 1998, a hypothesis was formulated that pinned the blame on two enzymes for creating a lack of blood flow that causes death to information transmitters in the brain (neurons). This neuronal damage is a factor in the development of Alzheimer’s disease.
Vegetable Oils & Obesity
What does that have to do with vegetable oils? Well, remember the damage to the cell membrane (lipid peroxidation) from above? The Japanese researchers believe that the cellular death caused by vegetable oils can negatively impact the hypothalamus, liver, and pancreas.
As a consequence, appetite can increase, leading to overeating. This is because the hypothalamus senses information from the hunger hormone, leptin. The hypothalamus also receives hunger signals from circulating free fatty acids.
Research has shown that people with obesity have higher concentrations of oxidized circulating fatty acids. In response to the overreaction of a specific fatty acid receptor, the regulation of calcium becomes disrupted. This is bad because calcium ions play a critical role in basically every cellular process.
Processed foods are made with cheap vegetable oils. The omega-6 fatty acids extend the shelf life in packaged/processed foods but do so at a steep price to human health. And cooking with vegetable oils is no better. Even though they keep processed foods stable, vegetable oils are highly unstable when heated. Use healthier oils at home such as avocado oil or walnut oil to cook with.