Why Processed Vegetable Oils are Bad
Your genes expect you to consume a variety of healthy fats as a significant part of your diet. Fats are among the most important molecules found in the human body. Cell membranes are comprised largely of fats; your brain is mostly fat; fat protects your organs and we store valuable energy in the form of saturated fat. Fats, as part of a meal, slow down absorption so that we can go longer without feeling hungry. In addition, they act as carriers for important fat-soluble vitamins A, D, E and K. Dietary fats are needed for the conversion of carotene to vitamin A, for mineral absorption and for a host of other processes.
That brings us to what fats you should eat, or shouldn’t you eat. It’s important to distinguish between the healthy and the harmful fats. Most dietary fats found in their natural state – especially saturated fats – are good for us.
When we look at closely at the evidence, it’s easy to figure out which oils and fats are healthy, and processed vegetable oils are firmly on the “bad for us” list, while natural fats including from animals not only make our food tastier but can benefit our health. That’s why avoiding processed oils (and embracing healthy sources of saturated fat, monounsaturated fat, and omega-3’s) is a major point of Primal/Paleo/Ancestral eating.
Unlike traditional fats (butter, tallow, lard, olive oil, etc.) processed vegetable oils are a very new addition to the “food” world. In fact, they were practically non-existent until the early 1900’s. With the invention of certain chemical processes and a need for “cheap” fat substitutions, the world of fat hasn’t been the same since.
Processed Vegetable Oils: What Are They Really?
Processed vegetable oils are unsaturated oils extracted from seeds, grains and legumes. Examples: soybean, corn, sunflower, cottonseed, and canola. To extract the oil from the seeds, grains and legumes requires extensive processing because the types of plants used for this don’t give up their oil easily. The processing includes mechanical extraction, high heat, industrial chemicals, deodorization, and toxic solvents.
Some plant-based oils are fine, like extra virgin olive oil, avocado oil, macadamia nut oil, and coconut oil, because they can be cold-pressed, require far less processing, retain more micronutrients and antioxidants, and have a more beneficial fatty acid profile.
Why Are Processed Vegetable Oils Bad for Us?
Partially hydrogenated fats (also known as trans fats) are among the most dangerous foods you can eat. These highly toxic fats are created by chemically treating vegetable and seed oils at high temperatures with hydrogen to render them solid. It’s an inexpensive way to enhance the shelf life of all manner of processed and frozen foods. It’s how they make margarine and fake butter spreads.
Partially hydrogenated trans fats oxidize to form free-radical chain reactions that have been shown to damage cell membranes and other tissue in your cardiovascular system, immune system, nervous system, and brain. Consumption of these agents has long been associated with cancer, heart disease, obesity, inflammation, and accelerated aging. They should never be consumed – sobering when you consider the widely cited estimate that 40 percent of the processed, packaged, frozen, junk food items in a typical supermarket contain these ingredients.
Another class of fats that warrant concern are refined high polyunsaturated vegetable/seed oils (PUFA’s), (canola, corn, safflower, and soybean; margarine and buttery sprays and spreads; assorted baked, frozen, packaged, and processed foods, mayonnaise and salad dressings). These are used extensively in frying because it gives the food a crispy texture, gives cookies their crunch and make bake goods flakey, making these processed convenient foods tasty and addictive, it’s hard to stop eating them once you start.
One problem with highly unsaturated oils is their susceptibility to oxidation. This can happen before the oil ever enters our body (such as while cooking, or if the oil is improperly stored and become rancid, as in clear bottles and in the light), but it can also happen in our bodies when the fats we consume from vegetable oils get incorporated into our tissues. While consuming already-oxidized oils is bad, oxidation of fats inside our body is also highly problematic. One of the ways a high omega-6 intake may contribute to cancer is by increasing the proportion of omega-6 in our cell membranes, leading to lipid peroxidation and ultimately DNA damage. By contrast, saturated and monounsaturated fats are much less prone to oxidation because of their chemical structure.
Because the predominant fat in processed vegetable oils is omega-6, you can easily end up consuming too much omega-6. Ideally, our intake of omega-6 versus omega-3 fats should be close to 1:1; but the ratio in Western Diets is anywhere between 10:1 to 25:1. We owe that to the high intake of vegetable oils (along with high grain consumption and grain-fed animal products).
The problem with that is that omega-6 fats contribute mainly to pro-inflammatory pathways, and when eaten in excess (or not balanced out with enough omega-3), they can stir up tons of trouble. Studies have liked high intakes of omega-6 (and a high ratio of omega-6 to omega-3) with a wide range of health problems, including certain cancers, cardiovascular disease, inflammatory diseases, osteoporosis, autoimmune disease, metabolic dysfunction, obesity, rheumatoid arthritis, IBS and asthma.
Given what we know, there is no reason to include processed vegetable oils in our diet. Emphasize intake of healthy fats, including saturated animal fats (ideally pasture-raised/grass-fed, or organic), oily, cold water fish (high in omega-3), and monounsaturated fat plant foods (avocado, macadamia nuts, olives/extra-virgin oil). A healthy “high-fat” (by SAD standards) diet supports optimal hormone and cellular function, promotes satiety, and raises HDL.
The source of omega-6 does make a difference. All omega-6 has largely been grouped together, regardless of the source. But whole-food sources of omega-6 also come packaged with other nutrients like dietary fiber, folic acid, niacin, tocopherols, vitamin B6, calcium, magnesium, potassium, phytosterols, vitamin E, and more. Just make sure you are also consuming healthy amounts of pre-formed EPA and DHA.
The top 15 omega-3 foods are:
- Atlantic Mackerel
- Salmon Fish Oil
- Cod Liver Oil
- Chia Seeds
- Alaskan Salmon
- Albacore Tuna
- White Fish
- Hemp Seeds
- Egg Yolks
Here are a few practical tips for modulating your omega-6 intake:
- Eat real food. Don’t fear the naturally occurring omega-6 in nuts, seeds, pastured meat, and other whole foods, especially if you are eating adequate amounts of omega-3 fatty acids. They are considered essential fatty acids, after all, and you do need some in your diet.
- Avoid industrial seed oils. Nix these nutrient-poor choices in favor of more nutritious and flavorful fats like olive oil, coconut oil, ghee, and other pastured animal fats. Fats with higher saturated fatty acid content tend to have higher smoke points.
- Don’t go overboard with the nut flours. This sort of goes along with “eat real food”. While nut flours can be a great substitute for wheat flour in baked goods, they are easy to eat in large quantities, and the omega-6 acids in these have the potential to be oxidized with heating. Switch it up with coconut flour or cassava flour. And, oh yes, save the baked treats for special occasions.
- Eat pre-formed EPA and DHA. Consuming cold-water fatty fish is a good idea for everybody, but it’s especially important for people who have diets high in omega-6 fats.
- Eat as many of your meals at home as you can. Just assume that anything you eat in a restaurant or that comes in a package has a long list of ingredients you don’t want to be consuming, unhealthy fats being just one of them.
For a detailed read about fats and cholesterol and the effect of them on your body, check out this article by Weston A. Price.