Navigating the world of cooking oils can be difficult. Most of us didn’t even know what seed oils were until a few years ago. They were and still are, often called vegetable oil.

The term ‘vegetable oil’ refers to any oil that comes from a plant seed.

Are Seed Oils Bad for You?

oil bottles

Some oils are better than others for your cooking, and more importantly, your health. Some plant oils are healthy to eat, but most should be avoided. Healthy oils include olive, coconut, avocado and flaxseed. Unhealthy oils are mass produced in large undustrial factories. They end up with no nutritional benefit once processing is complete.

Mass-produced oils should be avoided at all costs. These are called Industrial Seed Oils.

What are Industrial Seed Oils?

Anything called vegetable oil is a seed oil. These oils are highly refined and processed. They lack flavor and nutrients. Seed oils go rancid when heated during processing.

Unhealthy Seed Oils

  • Canola Oil (Rapeseed)
  • Corn Oil
  • Soybean Oil
  • Peanut Oil
  • Safflower Oil
  • Sunflower Oil
  • Cottonseed Oil
  • Grapeseed Oil
  • Rice Bran Oil
  • Vegetable shortening
  • Margarine

They are polyunsaturated, which means they have more than one double bond. They oxidise easily and should not be heated.

Oxidised oils/fats cause inflammation in the body. They are a major cause of many health problems today including Rheumatoid Arthritis, Alzheimer’s, Diabetes, Chronic Inflammation and more.

Are Seed Oils Essential Oils?

In short, no. They are not remotely essential.

Origins of Seed Oils

Unlike traditional fats like olive oil, coconut oil, butter, ghee, and lard, industrial seed oils are a recent addition to our diet. They only became a part of mainstream diets in the early 20th century with the advent of large-scale agriculture and processing.

Did you know they were originally used for making soap? William Proctor and James Gamble came up with the concept to replace soap that had been made by rendered pork fat by using the waste product of cottonseed oil manufacture.

Seed oils became mass-produced,
and therefore, very cheap to produce.

Refined oils became much cheaper to produce than animal fats like butter and pork rinds. Just compare the price of a bottle of canola oil to a bottle of olive oil.

Their affordability makes them the preferred source of cooking oil for restaurants, fast foods, bottled, processed and packaged foods.

How Industrial Seed Oils Are Made?

Seed oils are ultra-processed. This means they are extracted by mechanical pressing and solvent extraction. Then they go through a refining process.

  1. The seeds are gathered from the soy, corn, cotton, safflower, and rapeseed plants.
  2. Then the seeds are heated to extremely high temperatures, causing the unsaturated fatty acids to oxidise – this process creates harmful byproducts
  3. Seeds are then processed with a petroleum-based solvent, such as hexane, to maximize the amount of oil extracted from them
  4. Chemicals are used to deodorise the oils to improve their flavour, This process produces trans fats, which are harmful to your cardiovascular health
  5. The oils are then dyed to improve their color

In general, the process of extracting industrial seed oil creates an energy-dense, nutrient-poor oil that still has traces of chemical residues, trans fats, and oxidised byproducts that your body has to neutralise.

You can see how they are made here.

What Do Industrial Seed Oils do to Your Health?

Unlike actual vegetables, ‘vegetable oils’ and industrial seed oils are not nutrient-dense foods. In fact, they’re quite the opposite.

These oils are far from healthy, despite misleading claims that may appear on their labels.

1. Too much linoleic acid:

Our bodies are not designed to consume linoleic acid in such high quantities as that found in seed oils. We get roughly 8% of our calories from linoleic acid if we use seed oils for cooking, whereas previous generations would only get 1-3% of their calories from linoleic acid.

2. Unbalanced omega-6-to-omega-3 fatty acid ratios:

Before mass manufacturing, it was easy to maintain a ratio of 1:1 for omega-3 to omega-3 consumption. The Westernised diet has blown that ratio way out of balance, pushing it to the range of 10 or even 20:1. Industrial seed oils are the most significant contributor to the skewed ratio of omega-6 to omega-3. This imbalance leads to chronic inflammation which increases the risk of chronic diseases.

3. Easily oxidised and highly unstable:

Fats in industrial seed oil are highly unstable, meaning they oxidise easily when heated during cooking. In fact, even exposure to light can cause them to oxidise1.

4. Harmful additives:

Seed oils are highly unstable when exposed to light or when heated, so synthetic antioxidants are added to prevent them from oxidation. These antioxidants have a negative effect on your immune system, causing a disruption in its ability to fight other diseases, and can trigger allergies.

5. Derived from GMO crops:

Seed oils are primarily derived from genetically-modified crops which also raises questions about their safety for long-term consumption.

6. Repeated heating is linked to cardiovascular disease:

These oils are typically used by restaurants that reheat the oil for deep frying. While cost-effective, this only amplifies its negative qualities. By reheating industrial seed oil, the vitamin E content is also depleted.

Reheating increases the formation of free radicals that cause oxidative stress and damages DNA, proteins, and lipids. Therefore, repeatedly heated industrial seed oils are associated with high blood pressure, heart disease, and liver damage.

7. Links to common problems:

While some of these oils are marketed as ‘heart healthy’ research has shown that their high omega-6 fatty acid content leads to increased inflammation and chronic disease.

Connections are now being made between seed oils and asthma2, autoimmune conditions, diabetes, obesity, heart disease, gut health, infertility, the list goes on.

How to Avoid Industrial Seed Oils?

  • Clear your pantry of any foods that list a seed oil in their ingredient list.
  • Throw out any bottles of vegetable, canola, corn, cottonseed, soybean, sunflower, safflower, or peanut oils you have in your kitchen.
  • Cut processed foods out of your diet (chips, biscuits, jar sauces, etc.).
  • Cook at home more often, rather than eating out. Then you know what’s going into your food.
  • Avoid eating grain-fed meat. These animals are fed by-products of seed oils. Eat grass-fed meat instead.

Try These Oils Instead

Olive oil, coconut oil, and animal fats are natural, healthy sources of fatty acids. And, they all require minimum processing to get to the supermarket shelf.

Some oils work well raw in sauces and dressings, while others are suited for cooking or baking. Let’s look at the options.

For Dressing (to eat uncooked):

Extra Virgin Olive Oil (EVOO)

This is the purest form of olive oil, cold pressed and created with minimal processing. It has a low smoke point so is best consumed raw, not for cooking. Extra Virgin Olive oil is great for salads and making your own salad dressings. EVOO is a good source of Vitamin E.

Flaxseed Oil

This oil is anti-inflammatory and is a great oil for dressings. It’s not suitable for cooking and should be kept in the fridge. Downside: it’s quite unstable and goes rancid in about 6 weeks after pressing – within a few hours if left in sunlight. Eat flaxseeds whole instead.

For Cooking:

Virgin Olive Oil

Made with the same process as EVOO but with riper fruit. Although olive oil is a healthy fat, it has a low smoke point and is preferred as an uncooked food. Many people like to cook with it but it oxidises when heated removing the health benefits.

Coconut Oil

Coconut oil contains 90% saturated fat, which makes it very heat stable. It has a high smoke point so is safe to use in cooking at high temperatures. However, due to its high fat content, should be used in moderation.

Palm Oil

This oil works well in cooking, but most people will object to it due to the mass degradation of land in its production.

Avocado Oil

This oil is unrefined like extra virgin olive oil. However, it has a higher smoke point so is suitable for cooking at higher temperatures. Downside: It can be more expensive than other oils.

Almond Oil

Like extra virgin olive oil, almond oil is best used raw, as a dressing rather than being heated in cooking.

Not Oils, But Great Cooking Fats

While you may be limited in what oils are suitable for heating, you may want to try some of these animal fats as a replacement for the seed oils you may have been using.


If dairy isn’t a problem, then butter is an excellent option. It can be heated to approx. 200º before it starts to burn.


Ghee is made from clarified butter by heating the butter and allowing the milk portion to separate from the fat. It is, therefore, a good option for dairy-sensitive people. Ghee is also good for cooking at high temperatures.


Rendered from pigs, lard is high in saturated fat and suitable for cooking. Along with ghee, it is suitable for dairy intolerant people.


This fat rendered from beef, rather than pork. Another excellent option for cooking at high temperatures, including deep-frying.

Duck Fat

Another animal fat with a high smoke point. It has a beautiful flavor and works really well for cooking roast vegetables.

While swapping vegetable oils for healthier oils may not seem like a big diet shift, its benefits go well beyond aesthetics. Removing them from your diet is an easy change to make for big benefits for your health.

You’ll find some more information on healthy fats here.

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