I absolutely hate to come off as an alarmist. It’s just not my style. But if there is one time in which I’m willing to channel my inner Chicken Little, it’s while making the case to avoid vegetable oil.
As a Nutritional Therapist, I’ve been asked a few times “If I were to make one change to improve my health, what would you recommend?” My response to that question is always to start making an effort to avoid vegetable oils.
Vegetable oils are the one food that I have a rule against bringing into our home. I read labels to make sure that we avoid them, and I just don’t buy products that contain them. Though we eat a primarily unprocessed diet, you will find (organic) processed meats, all-purpose flour and regular old sugar (for making snickerdoodles at Christmas), glutenous beer, and condiments that have added sugar (ketchup and my favorite almond butter) in our home. But you won’t find vegetable oil.
Because it’s nearly impossible to avoid refined vegetable oil while eating out, and given the reasons below for reducing intake as much as possible, I think it’s important that we avoid them all together at home. (To find out what we use at home, visit my list of my seven favorite healthy fats.)
What is a Vegetable Oil?
‘Vegetable oil’ (sometimes referred to as ‘seed oil’) is a generic term used to describe oils that are created from crops like corn, soybean, cottonseed, safflower, sunflower, and ‘canola’ (more on canola in a future post). All fats and oils (the difference is solid versus liquid) are a combination of the three types of fat: saturated, monounsaturated, and polyunsaturated. Vegetable oils are high in polyunsaturated fatty acids (PUFAs).
Americans are consuming vegetable oil in massive quantities. This study found that the consumption of soybean oil increased more than 1000-fold during the twentieth century. The same study found that soybean oil, a food that was basically unheard of in 1900, made up 7% of the calories in the average American diet in 1999. (And that’s just soybean oil!)
How are we consuming seven percent of our calories in a food that wasn’t even a food a century ago? Because it’s everywhere. When the (unfounded) fear of saturated fat arose in the 1950s and 60s, fat consumption dramatically shifted to PUFAs. And, it’s cheaper than saturated fats like coconut oil, lard, or tallow.
Even if you are not cooking with vegetable oils in your home, there’s a good chance you are consuming much more than you realize. Nearly everything you eat outside your home, either in fast food or a restaurant, especially if it is fried, is cooked in vegetable oil. Trying to be healthy and ordering a salad? The dressing is most probably made with vegetable oils.
Processed foods are also full of vegetable oils, and Americans eat a lot of these. This study, while it was focused on added sugar, shows that more than 50% of calories for Americans come from ultra-processed foods. Take a look at the labels of the foods in your pantry or freezer and look for vegetable oils. You are likely to find them in in the ingredients of most. Remember, they may be labeled ‘vegetable oil’ or listed by the seed’s name.
Even foods that seem to be made from oils other than vegetable oil can be deceiving. Here are a few photos I took at Whole Foods of salad dressings that appear to be olive oil based.
Let me also share a few charts with you.
Here are the amounts of added fats in the US diet over the past decades:
And here are a few statistics on chronic illness in the US over the past few decades.
(hospitalization for heart failure; source)
I’m in no way implying that a couple of charts pulled off the internet equal causation. But it is obvious that something(s) has caused an increase in chronic illness in the US. That the increased consumption of vegetable oils could be a factor is food for thought (pun intended, I love puns), and reason to consider the arguments against avoiding vegetable oils laid out in the next section.
I’ve packed a ton of detail into the next section. If you’d like an abridged version, jump on down to the infographic at the end. If you’re curious about the nitty gritty, read on.
Why We Avoid Vegetable Oils
1. The processing involves and results in known toxins.
When was the last time you enjoyed a delicious, fatty piece of corn? Right. Crops commonly used to make seed oils are not known for their fat content. It takes a lot of processing to go from a kernel of corn or a soybean to a bottle of vegetable oil. Unlike the fat available in high-fat foods like coconut, palm, and olive, that can be removed mechanically, fat from seed oils needs to be removed chemically.
Oil is extracted from the seeds by high heat and pressure. Hexane, a byproduct of refining gasoline and identified by both the FDA and EPA as toxic, is often used to extract the last bits of oil from the seed. Once extracted, oils are washed at high heat to remove impurities, but are still foul looking and smelling. Additional chemicals are used to bleach, deodorize, and possibly recolor the oils before they land on store shelves.
This processing also removes almost all of the naturally occurring antioxidants in the seeds, which we’ll explore the effects of shortly.
To really understand the processing, I recommend watching the four minute video below (it’s a canola oil commercial, so please ignore the first minute of propaganda).
If you’re not already upset that the product resulting from this sort of processing is considered a food, let me add that trace amounts of the chemicals used in processing are allowed in the final product. While the levels are minimal, very little research has been conducted to determine the effect on human consumption at these levels.
2. PUFAs oxidize easily.
Polyunsaturated means that there are multiple kinks (missing hydrogen atoms) in the fatty acid chain, which makes a PUFA the most chemically unstable type of fat. This is why they are liquid at room temperature, versus solid like a saturated fat (‘saturated’ meaning no missing hydrogen atoms). Because PUFAs are highly unstable, it takes very little for a PUFA to oxidize, including everyday light or room temperature. Oxidization results in damaged (rancid) fats and the formation of free radicals.
Quick science lesson: Simply put, a free radical is a molecule that has an unpaired electron. It “attacks” other molecules to steal an electron, which turns that molecule into a free radical, causing a chain reaction that can destroy cells and damage DNA. Some amount of free radicals are naturally occurring and useful as they can perform functions like fighting viruses. But too many is dangerous, as they’ve been linked to cancer, Alzheimers, etc. Antioxidants, like Vitamin E, are able to stop the chain of destruction by donating an antioxidant to the free radical. But as we learned, the processing of vegetable oils removes almost all the antioxidants that are naturally available in these crops. (resource)
So, if you recall, vegetable oils are mostly PUFAs. If everyday light can cause a PUFA to oxidize, imagine what all the high heat processing that is used to create a bottle of vegetable oil in the first place does to the fats? Yep. Oxidation.
And once processed, the oil is stored in a clear bottle on a grocery store shelf, exposing it to more light and potentially heat. More oxidation.
And then we bring the bottle home, store it on the counter, and heat the oil for cooking. More light, more heat, even more oxidation.
Or, when we go out to eat, vegetable oils are heated in a fryer over and over again for foods like french fries, chicken tenders, tortilla chips, fish sticks, fried chicken sandwiches, etc. I’m starting to sound like a parrot, but even more oxidation.
While completely unscientific, I came across a thread on how often fast food restaurants change out fryers, according to employees, and if true, it’s scary. Imagine just how many times oil is heated in a week at a busy McDonalds.
I will also point out that the foods I just listed above make up 75% of the items on the kid’s menus we are presented with in restaurants. Excuse me while I go meditate.
Once we consume the oil, the damaged fats are inflammatory and free radicals attack healthy cells. Inflammation is routinely listed as a contributor to chronic disease.
Rancid fats are are not safe for human consumption, and there is (high) potential for refined vegetable oil to be rancid even before it is purchased.
3. PUFAs do not provide fat ratios that support optimal health.
Let’s pretend for a minute that vegetable oils are not created via a process that results in toxic chemicals and that they aren’t (likely) rancid. Are they still healthy?
Fats play many important roles in our body, like being the building blocks of hormones and being necessary for the absorption of fat-soluble vitamins. Another incredibly important function is that they make up the membrane of ever single cell in the body. All 30 something trillion of them. Cell membranes are important because they control what is allowed in and out of every cell. The quality and type of fat we eat affects cellular function.
How much PUFA should we be eating? The best estimates are about 4% of our total fat intake. This is a ‘best estimate’ because it is bioindividual and there is not one perfect number for everyone. Some cultures traditionally ate a much higher percentage, but it came form naturally occurring PUFA, not from refined vegetable oil.
For a quick review, 7% of total calories, not just fat, is coming from soybean oil alone, which is 58% PUFA. This doesn’t count all the other sources of natural and manmade PUFAs that we consume, so it’s clear that the PUFA percentage of total fat intake is well above the recommended 4%. Some estimates show that it’s around 30%.
What is the result of our body expecting 4% of our fat to be PUFA, but instead receiving 30% (with a large percentage of that being rancid)? With high levels of PUFAs, our body does not have the required building blocks to produce hormones or strong, permeable cell membranes.
And there’s another problem.
PUFAs are made of Omega-3 and Omega-6 essential fatty acids, and in refined vegetable oils the percentage of Omega-6 is very high. Ideally, we want our overall intake to be somewhere between 1:1 and 1:3 (Omega-3 to 6).
Why does the ratio of Omega-3 to Omega-6 matter? Omega-3 is anti-inflammatory, whereas Omega-6 is inflammatory. Having some inflammatory fatty acid is important for optimal health. For instance, with an injury. The body first inflames so that it can heal (think of redness and swelling). But high ratios of Omega-6 to Omega-3 result in chronic inflammation and current estimates for the average American is a 16:1 ratio. Sixteen to one. I can’t drill this point home hard enough: chronic inflammation is continually linked to chronic disease. Go ahead and take a look at those graphs above one more time.
Please note, I’m not vilifying Omega-6. It is an essential fatty acid and we need it. The problem is the quantities available in vegetable oils and the amount of vegetable oils we consume. It’s much, much harder to skew the ratio when eating whole foods sources of Omega-6, like seeds, nuts, and avocados.
4. Vegetable Oils Are Detrimental to Children and Fertility
This heading is misleading because, obviously, vegetable oil is detrimental to humans, regardless of age or reproductive status. But because my passion is supporting healthier families, I want to explore a few ways in which refined vegetable oils are detrimental specifically to the youngest of us and those looking to conceive. However, I want to do them justice and this post is already quite long. I’ll expand on this one in an upcoming post.
How to Reduce Vegetable Oil Consumption
How much you choose to reduce your or your family’s vegetable oil consumption is up to you. I choose to exclude all vegetable oils from our home, but I understand that when eat out, I’m guaranteed to consume some. This is worth it to me to enjoy meals out with my family and friends and to have a break from cooking here and there. I also like to think that the nourishing practices I follow, like consuming liver and bone broth, aiming for six servings of veggies per day, staying hydrated, and
getting adequate sleep, help my body process the rancid fats, reduce inflammation, and stop the free radical damage.
If you’re ready to limit your intake, here are my top three tips:
- This probably seems obvious, but remove all the vegetable cooking oils from your home. If they aren’t there, you can’t use them. Look for canola oil, vegetable oil, corn oil, etc. and toss them. Also, if you have any shortening or butter replacement products like margarine, toss those. We’ll talk more about the solid products in a separate post.
- Read labels in the store. Again, how deep you decide to go on removing oils from your home is up to you, but you will find that many, many processed products are going to have some form of vegetable oil. And the oil will be listed in different ways.
- When dining out, avoid what vegetable oils you are able to by skipping fried foods, salad dressings, and other oil based sauces. When possible, request that your food be cooked in butter or olive oil.
Phew. That’s probably more than you wanted to know about vegetable oils, but as they say “knowledge is power”. Confused about what fats are healthy? Check out the list of my seven favorite healthy fats. Have any questions about vegetable oils? Leave them in the comments and I’ll get back to you.
If you found this informative, I’d be honored if you’d share the following infographic to help spread the word.
Better Beauty News
I'm a believer that we shouldn't have to compromise our health in the name of beauty. Or performance in the name of safety.