A Healthy Choice or Hidden Risk: Is Vegetable Oil Bad for You?

So, is vegetable oil bad for you? Is it a deservingly maligned food substance or have we cracked down too harshly on this versatile product? Here we'll explain what vegetable oil is, how it is produced and what impact it may have on your health, helping you make an informed choice about what you consume.

Is Vegetable Oil Bad for You?

The answer here is, vegetable oil isn't the best option, but it also won't kill you (today).

In the era of popular culture, believing that saturated fat caused heart disease, products like vegetable oil, canola oil and margarine were favourable substitutes. These products were championed as heart-healthy alternatives to butter, lard or tallow.

However, now that this myth has been thoroughly debunked, the truth about processed oils is emerging. Vegetable oil has been the subject of (deserved) scrutiny in the health and wellness sectors. Nutritionists, health advocates and researchers are increasingly questioning whether these highly processed oils contribute to chronic inflammation and other health issues.

Ultimately, the evidence suggests that relying on industrially refined seed oils is not optimal for long-term health. It's certainly a less desirable choice compared to natural fats humans have consumed for centuries. Overall, it's more something to consume minimally and mindfully, choosing alternatives wherever you can.

What Is Vegetable Oil?

Vegetable oil is typically a blend of various oils, such as soy, sunflower, safflower, corn and sometimes canola oil.

It's often a broad classification used to describe oils extracted from seeds, grains, beans or fruit. While technically plant-based, most of the oils sold under this label are not derived from vegetables in the culinary sense. Instead, they are extracted from crops grown on a massive industrial scale.

Common types of oils that comprise vegetable oil include:

• Soybean Oil: The most widely used variety, frequently found as the primary ingredient in generic "vegetable oil" blends and processed snack foods.

• Canola (Rapeseed) Oil: Marketed for its high smoke point and low saturated fat content, though it undergoes extensive industrial processing to become palatable.

• Corn Oil: A high-volume byproduct of the maize industry, commonly utilised in commercial frying due to its stability at high temperatures.

• Sunflower Oil: Extracted from sunflower seeds, this oil is a significant source of Vitamin E, though processing may impact nutrient profile.

• Safflower Oil: Chemically similar to sunflower oil, it is often used in high-heat cooking and as a base for many bottled dressings.

• Cottonseed Oil: Historically one of the first mass-produced oils, it remains a staple in the production of margarine and shelf-stable packaged goods.

How Is Vegetable Oil Made?

Corn, soy and other ingredients commonly used to make vegetable oil aren't exactly brimming with oil content. Extracting any amount of oil from these foods typically involves a complex processing method using bleach or solvents.

The result is a highly refined product that's stable, has a high smoke point and a long shelf life, making it ideal for restaurant use or commercial cooking. However, this process strips away any natural antioxidants, vitamins and minerals that would be readily available in the starting ingredient.

Here's what's involved in the production of vegetable oil:

The Industrial Extraction Method

1. Extraction: The seeds or grains are crushed and heated. To maximise the yield, manufacturers typically use a petroleum-based solvent, most commonly hexane, to dissolve the oil out of the seed pulp.

2. Refining: The crude oil is then treated with chemicals to remove impurities, gums, and waxes.

3. Bleaching: The oil is filtered through bleaching clay to remove pigments, resulting in the light, golden colour consumers expect.

4. Deodorising: Because the processing steps can create unpleasant smells, the oil undergoes high-temperature steam deodorisation. This removes volatile compounds and odours, creating a bland, neutral taste, which is ready to be packaged and sold.

Potential Health Concerns of Vegetable Oils

The Omega-6 to Omega-3 Imbalance

Two types of polyunsaturated fats (PUFAs) are important for human health: Omega-3 and Omega-6. The body cannot produce these on its own, so these fats must come from food.

Omega-3 fatty acids:

Found in fatty fish, seafood, phytoplankton, flaxseeds, walnuts, chia seeds and some leafy green vegetables and are generally anti-inflammatory, cardioprotective and neuroprotective. These compounds are converted to EPA and DHA in the body and play a key role in cell membrane function and protection.

Omega-6 fatty acids:

Found in high concentrations in vegetable oils, meat, poultry, eggs and certain processed foods. Excessive omega-6 fat intake can be pro-inflammatory and may contribute to a range of health conditions. While acute inflammation is a necessary physiological response to injury, chronic, low-grade inflammation is a root cause of many diseases, including cancer and various autoimmune disorders.

Oxidation and Instability

Polyunsaturated fats are chemically unstable. Their chemical structure contains multiple double bonds, which makes them highly reactive to oxygen and heat. When vegetable oils are exposed to the high heat of the refining process, and later, to the high heat of your frying pan, they can oxidise. Oxidised oils create free radicals, which are unstable molecules that can damage cells in the body.

This repeated heating generates harmful compounds like aldehydes, which have been linked to various health risks, such as an increased risk of heart disease and cancer. It also accelerates the ageing process of your cells, impacting your immune health, skin health and capacity to heal.

Trans Fats and Hydrogenation

Historically, vegetable oils were often chemically altered through a process called hydrogenation to make them solid at room temperature (like margarine or shortening). This process creates trans fats, which are well recognised as harmful to heart health.

While strict regulations have significantly reduced trans fats in most commercial food products, refined vegetable oils may still contain small amounts of trans fats due to the high heat used during the deodorisation phase.

Superior Alternatives: Some Better Oils for Your Health

If you are looking to optimise your health, swapping out refined vegetable oils for more stable, nutrient-dense fats is one of the most impactful dietary changes you can make. Here are some alternatives to stock in your pantry.

1. Extra Virgin Olive Oil (EVOO)

Widely considered the gold standard of healthy fats, Extra Virgin Olive Oil is extracted from the fruit of the olive tree using mechanical pressing. It is rich in monounsaturated fats and potent plant polyphenols.

How should I use it?

Salad dressings, drizzling over roasted vegetables, and low-to-medium heat cooking.

What makes it healthy?

Extensive research links EVOO and diets such as the Mediterranean diet with a reduced risk of diseases such as diabetes, cancer, depression, obesity and asthma. Contrary to popular belief, high-quality EVOO is actually quite stable for home cooking with a high heat tolerance due to its high antioxidant content. This is a great alternative to vegetable oil and canola oil for the average household.

2. Avocado Oil

Like olive oil, avocado oil is pressed from the flesh of the fruit, not the seed. It has a very similar nutritional profile to olive oil, being high in heart-healthy monounsaturated fats (oleic acid).

How should I use it?

High-heat cooking, baking and searing.

What makes it healthy?

With a smoke point of roughly 270°C, avocado oil is one of the most heat-stable oils available, making it a safer choice for stir-fries than vegetable oils. It can be a bit expensive, but it's another good option with a mild, mellow buttery flavour.

3. Coconut Oil

Coconut oil fell out of favour in the past due to its high saturated fat content, but in moderation, it's a worthwhile consideration as part of a balanced diet. It is composed mainly of medium-chain triglycerides (MCTs), which the body can easily burn for energy.

How should I use it?

Baking and sautéing, particularly in Asian or tropical-style dishes.

What makes it healthy?

Saturated fats are chemically stable and are commonly solid at room temperature. This means coconut oil is highly resistant to oxidation at high heat, making it a safe and healthy option for all sorts of cooking adventures.

4. Butter and Ghee

High-quality grass-fed butter and ghee (clarified butter) are excellent traditional fats. Ghee has had the milk solids removed, leaving pure butterfat.

How should I use it?

Baking, roasting, and pan-frying.

What makes it healthy?

Butter has a moderately high smoke point, while ghee has a very high smoke point and provides fat-soluble vitamins like Vitamin A, D, and K2.

5. Peanut Oil

Peanut oil is a plant-based oil with a relatively high smoke point, making it suitable for a variety of cooking methods. It is commonly used in Asian cuisine and deep-frying due to its ability to withstand high temperatures without oxidising.

How should I use it?

Stir-frying, deep-frying, and sautéing.

What makes it healthy?

Peanut oil contains heart-healthy monounsaturated fats and a very high smoke point, making it versatile for everyday cooking (as long as you don't mind a peanutty flavour in your food!)

Tips for Navigating Vegetable Oil Intake

Eliminating refined oils entirely can be challenging because they are ubiquitous in the modern food system. However, you can significantly reduce your consumption by being informed and aware.

1. Read the Fine Print

Vegetable oils are often hidden ingredients in packaged food. Check the labels of:

• Salad dressings and mayonnaise

• Crackers, chips, and biscuits

• Store-bought dips like hummus

• Plant-based milk alternatives

Look for brands that specifically use "100% Olive Oil" or "Avocado Oil." Be wary of "Olive Oil Blends," or "spreadable" butters, which are often cut with cheaper canola or soybean oil.

If you want to learn how to read and understand Australian food labels, check out this article here.

2. Take Control in the Kitchen

The easiest way to avoid industrial oils is to cook from scratch with your favourite healthy oil. 

Try making your own salad dressing. A simple vinaigrette made with EVOO, lemon juice, Dijon mustard, honey and salt takes seconds to make and is infinitely healthier than store-bought versions. 

Make your own nut milk! It’s a whole lot easier than you think, with no need for any additional emulsifiers like vegetable oil.

Also consider what spreads you use. Choose butter, avocado, or nut butter on toast instead of margarine or other synthetic spreads.

3. Be Mindful When Dining Out

Restaurants often use the cheapest oils available to keep costs low, which is critical to keep in mind. Foods like chips, calamari, fried chicken and spring rolls are almost guaranteed to be cooked in industrial vegetable oils that have been heated repeatedly. Opt for grilled, roasted, or steamed dishes instead.

Is Canola Oil Different from Vegetable Oil?

Canola oil is not the same thing as vegetable oil; however, they are often used interchangeably. Canola oil is also known as rapeseed oil and is often found as an ingredient in vegetable oil, mixed with other cropseed oils.

Choose Quality Over Convenience When Consuming Oils

The truth is, vegetable oil isn't great, especially when there is a range of alternative oils to choose from as a home cook. Much depends on what's happening or happened with the oil before you consume it. The chemically induced refining process alone is problematic.

However, as long as you enjoy a balanced, healthy diet, you should generally be able to tolerate it in strict moderation. Remember, when you choose less processed, nutrient-dense fats like olive oil, avocado oil, and butter, you are providing your body with stable energy and essential nutrients rather than inflammatory compounds. The next time you are in the supermarket, check the ingredients, understand the processing, and choose an oil that makes sense for you, your cooking and your future health.