Take a moment and explore the food inside your pantry and refrigerator. Pay close attention to the list of ingredients provided somewhere on the packaging of these foods. Do you notice any similarities? Perhaps the prevalence of either sugar or vegetable oil has caught your eye? The former is a topic worthy of a separate discussion. Today, I want to talk about the use of certain industrially processed seed oils known colloquially as “vegetable oil” and how they negatively impact your health.
One of the traditional pieces of advice still put forth by some healthcare practitioners today is somewhere in the realm of “Eat less fat, particularly saturated fat, and keep your cholesterol low. Both cause heart disease!” This is absolute nonsense. Despite overwhelming evidence to the contrary, the idea that animal fats are unhealthy prevails among the “educated.” The origin of this lie dates back to observational research performed in the 1950s by Ancel Keys. Keys noted that groups of starving individuals showed fewer incidences of death from heart disease than fully fed populations. To explain this, Keys postulated that eating a full-calorie diet meant consumption of larger quantities of fat and cholesterol which would accumulate in the blood and cause atherosclerosis.
Keys set out to prove his hypothesis by observing fat consumption in 22 countries and how it correlated to heart disease. In a highly unscientific manner, Keys decided to publish the results from only seven countries which at the time showed a near-perfect correlation between fat intake and the number of deaths from heart disease. Why weren’t the other countries included? Keys never mentioned why, but a quick look at the data reveals that the remaining countries show no correlation between fat intake and deaths. If one were to imitate Keys and cherry-pick a different set of countries, for example, Germany, Switzerland, Austria, Israel, and Norway, the opposite conclusion could be drawn. For the countries above, a near-perfect negative association emerges between fat intake and the number of deaths from heart disease.
Despite the irregularities in the data, by the mid-1960s organizations such as the American Heart Association and American Medical Association began publishing recommendations to avoid saturated fat and replace it with polyunsaturated vegetable oils. In 1980, the US Department of Health joined the US Department of Agriculture to instruct Americans to “avoid too much fat, saturated fat, and cholesterol” because it led to heart disease. With the weight of the US government behind them, the agricultural industry dove headfirst into promoting and manufacturing consumer products rich in vegetable oil. How convenient for the food industry that these new ingredients were but a fraction of the price of animal fat and fruit oils!
Before we continue, can you name which vegetables consumed by humans provide significant amounts of oil? No? The fact is there is no such thing as “vegetable oil.” Oils not derived from mechanical pressing, such as high-fat fruits or nuts, are extracted from the seeds of certain plants through a highly refined industrial process. The sheer volume of these ingredients used in modern food processing has accelerated dramatically in the last century not only because of the change in dietary guidelines but largely because seed oils are demonstrably cheaper than healthier alternatives such as olive oil, butter, or tallow. Fortunately for the food industry, a single flick of the marketing wand turns obscure substances like soybean and rapeseed oil into magic vegetable oil. And didn’t grandma say you should eat your vegetables? Sadly, the lack of awareness of the ramifications of a diet containing seed oils has led to a multitude of health problems for consumers.
The first thing consumers must understand about fats is their structure and general stability. Excluding artificial trans fats, there are three structures of fat molecules. Artificial trans fats are simply seed oils that have been hydrogenated and thus become solid at room temperature. In 2015, artificial trans fats were outlawed by the USDA due to the overwhelming evidence of increased risk for heart disease. This fact alone should cast significant doubt about the safety of seed oils in our food. The other three forms of fat are saturated, monounsaturated, and polyunsaturated. Saturated fat is by far the most stable fat and therefore less prone to oxidation than monounsaturated and polyunsaturated fats. Monounsaturated fat is still fairly stable but should be protected from light and heat so as not to go rancid (the effects of oxidation). Polyunsaturated fats are the least stable and therefore most prone to oxidation. Most nuts and seeds oils contain a majority of fats that fall under this category.
Why is oxidation dangerous? When fats are oxidized they are broken down into chemicals that damage the integrity of cells in our body. This process, repeated over and over, can facilitate the growth of cancer and arterial lesions. Before the advent of industrialized oils, humans consumed mostly saturated fat which as we know is very stable and does not oxidize much. For the small amounts of oxidized fats that were consumed, our bodies would employ endogenous antioxidants, such as glutathione and coenzyme Q10, to tamper out the damage. Fast forward to present day and the average person is consuming quantities of highly unstable polyunsaturated fats far beyond what their body can manage. And yet, our body requires polyunsaturated fats, namely omega-3 and omega-6, for proper functioning. Is this a paradox? Not quite. Polyunsaturated fats by themselves are not the enemy. The naturally occurring polyunsaturated fats found in animals and raw nuts are quite safe and desirable. Rather the industrialized process of refining plant seeds to make cooking oils, causing rampant oxidization, is the culprit.
The refining process is not a simple one. Since mechanical pressing of seeds yields a low 35% and leaves many impurities in the oil, manufacturers employ a wholly different process. The seeds extracted from rapeseed plants, for example, are treated with chemical solvents and heat to extract, decolor, degum, bleach, and finally deodorize the resulting oil. In each of these steps, oxidation occurs. Then these oils are shipped out in clear containers where light and heat will induce more oxidation. Finally, the consumer purchases a bottle of canola oil for cooking upon which more oxidation will occur.
When consumers ingest processed seed oils, they interact directly with the cholesterol in our bodies. Most cholesterol, roughly 70%, is created endogenously by the body and one of its primary functions is to bind fat in the bloodstream together so that nutrients can be properly transported (otherwise fat would float around in our blood like cream on top of milk). Of the cholesterol floating around, roughly 60-80% is LDL and the remainder HDL. The main difference between these two types is not that one is “bad” or “good,” which is truly bad science, but that LDL transports fat to cells while HDL collects unused fats and returns them to the liver. So why do we constantly hear people spout that LDL is bad for you? Because out of the two types, it’s LDL cholesterol that is most affected by oxidized fat.
When LDL particles pick up oxidized fats, typically in the form of polyunsaturated fats from seed oils, a chain of events begins. First, our livers will respond by releasing antioxidants to combat the damage. When this system is overloaded and the LDL particle runs out of antioxidant help, immune cells called macrophages target and envelop them before they can do further damage. This system can be overloaded too, and when that happens, we start to see the negative impacts accumulate. Again, it is damaged LDL cholesterol that is the problem. Two individuals can both have high LDL and yet be oppositely healthy. There are now tests that can identify the degree of LDL oxidation in the body.
What then happens to these damaged LDL particles? The cells in our body no longer register them as nutrient-carrying counterparts. The oxidized transports will circulate in the blood and occasionally embed themselves in the endothelium of arterial walls. This process can be catalyzed by the presence of fructose (note that high fructose corn syrup and other added sugars are quite common in processed foods containing seed oils). Once the damaged LDL particle is attached to the arterial wall, it releases the burned half remains of unsaturated fats into the cell lining which sends signals for an immune response. The result is an attack on our arteries and the production of atherosclerotic lesions (you will always find dead immune cells and oxidized LDL in arterial lesions).
An interesting study demonstrating this outcome at the population level was conducted in 1965. The London Hospital Study followed three groups of middle-aged men divided by diet: one eating a standard British diet, one instructed to replace animal fats with corn oil (60% polyunsaturated), and the last told to replace animal fats with olive oil (9% polyunsaturated). Despite cholesterol being 25% lower in the corn oil group at the end of the study, the rate of heart attacks suffered was 48%, nearly half! The group told to eat a standard British diet suffered a heart attack rate of only 28%. Other studies and observations associate higher consumption of polyunsaturated fats with cancer, macular degeneration, and even allergies. More information about these studies and others can be found in David Gillespie’s Toxic Oil. I highly recommend this book (which was a significant source of information for this piece).
My solution to the problem described above is a simple one. Do not cook with seed oils and avoid eating regularly at restaurants that use them. Stick to grass-fed butter or tallow when heated fats are needed and cold-pressed olive oil or coconut oil when necessary. It’s simply not worth the cost to your health to use anything else. Unfortunately, many products will be off limit as a result of this change. I find the satisfaction of performing at my best far more intoxicating than any short-term pleasure derived from processed foods. A major component to this fact is the absence of seed oils and the accompanying inflammation (there are other factors involved too, which I may choose to address in future writings). Each person needs to make their own independent, denial-free assessment as to whether this is a change they are willing to make long term. I believe it only takes a few days of removing these foods before benefits are felt. Good luck and may the power of discipline prevail!