The Hidden Truth About Your Cooking Oil: What You Need to Know for Your Health

Kylee Melo, RD, RDN
Aug 14
5 min read

Cooking Oils: From Ancient Presses to Modern Kitchens

Cooking oils play a crucial role in our daily cooking, affecting flavor, nutrition, and even health. With a wide variety of oils available, understanding their origins and production methods helps us make better choices. This blog post takes a closer look at popular cooking oils, their histories, how they are made, and evaluates their health impacts in practical terms.

The History of Cooking Oils

Cooking oils have a rich history that dates back to ancient civilizations. Early cultures used methods to press seeds and nuts, creating oils for cooking and preservation. For instance, olive oil has been a staple in Mediterranean diets for thousands of years due to its distinct flavor and health benefits. Similarly, sesame oil has been used in Asia for culinary and medicinal purposes.

Over the years, advancements in agriculture led to increased oil varieties. By the mid-20th century, the rise of industrial farming contributed to the mass production of oils such as canola, vegetable, and corn oil, making them more affordable and accessible to consumers.

Canola Oil: From Industrial Lubricant to Kitchen Staple

Canola oil is derived from the seeds of the canola plant, which is a genetically modified version of rapeseed developed in Canada in the 1970s. Its name, "canola," stands for "Canadian oil, low acid."

It's interesting to note that the rapeseed plant, from which canola was bred, actually has a history of industrial use. Early varieties of rapeseed oil were primarily used as industrial lubricants and in fuels due to their properties. The original rapeseed plant contained high levels of erucic acid, making it unsuitable for human consumption. Canadian scientists developed the new "canola" variety to address this, but the processing methods largely remained industrial.

The production process of canola oil involves several stages:

Harvesting and Cleaning: Canola seeds are harvested and cleaned to remove impurities.
Crushing: The seeds are then crushed to extract the oil.
Intensive Refinement (RBD Process): Finally, the oil undergoes extensive refining to remove impurities, resulting in a product with a light flavor and longer shelf life. This refining process is often referred to as RBD: Refined, Bleached, Deodorized. It involves subjecting the oil to high heat, chemical solvents like hexane for extraction, followed by bleaching (to remove color) and deodorizing (extreme heat and vacuum to remove strong odors and flavors). This harsh processing can fundamentally alter the oil.

Despite its low saturated fat content, this intensive refining process significantly removes beneficial nutrients like antioxidants that were present in the original seed. Additionally, the high heat and pressure can lead to oxidation (creating harmful free radicals that damage cells) and even the formation of small amounts of unhealthy trans fats, even in non-hydrogenated oils. Concerns also exist about the long-term health effects of consuming oils derived from genetically modified crops, with research indicating that about 87% of canola crops in the United States are genetically modified.

Vegetable Oil: A Blend of Many, A Source of Inflammation

Vegetable oil is a broad category encompassing various oils, primarily soybean, palm, and sunflower. This oil gained traction in the mid-20th century primarily due to its low cost and versatility in cooking.

The production of vegetable oil generally involves:

Extraction: Oils are extracted using mechanical pressing or often, harsh chemical methods like solvent extraction (e.g., using hexane).
Refining: The oil then undergoes the RBD (Refined, Bleached, Deodorized) process, similar to canola, to improve flavor, color, and extend shelf life. This high-heat and chemical treatment can degrade the oil.

Even though vegetable oil is widely used, it's important to note that it typically contains high amounts of omega-6 fatty acids. While omega-6s are essential, the intensive processing damages these fats, and excessive consumption of them, especially when unbalanced with omega-3s, can lead to widespread inflammation in the body. This inflammation is a key driver linked to numerous chronic health issues, including heart disease. Experts recommend that omega-6 intake should not exceed 4% of total daily calories, highlighting the importance of moderation in using these heavily processed vegetable oils.

Corn Oil: The "Sweet" Oil with Hidden Downsides

Corn oil is extracted from the germ of corn kernels and has been popular in the United States since the 1800s. Its high smoke point makes it an excellent choice for frying and baking.

To produce corn oil, the following process is used:

Steeping and Milling: Corn kernels are steeped in water and milled to separate the germ.
Extraction: The oil is then extracted using heat or chemical solvents before undergoing extensive refining.

While corn oil is useful for high-temperature cooking, it also contains high levels of omega-6 fatty acids and lacks many beneficial nutrients when compared to less processed oils. The harsh processing methods strip away valuable compounds and can make the remaining fats more prone to oxidation. Experts advise limiting its use, especially since excess consumption of these processed omega-6 oils could contribute to similar inflammatory health problems associated with other processed vegetable oils.

The Healthier Alternatives: Extra Virgin Olive Oil and Coconut Oil

Now let’s highlight two oils considered healthier options that retain more of their natural integrity: extra virgin olive oil and coconut oil.

Extra Virgin Olive Oil: The Gold Standard Extra virgin olive oil (EVOO) is made from the first cold pressing of olives, which helps retain their natural flavors and nutrients. This oil has been cherished since ancient Greek and Roman times for its taste and health benefits.

Using EVOO in cooking enhances the flavor of dishes such as salads and marinades. Nutritionally, it is rich in monounsaturated fats and antioxidants. In fact, studies have shown that diets rich in olive oil can lower the risk of heart disease by up to 30%, making it a top choice for healthy cooking.

Coconut Oil: The Tropical Treasure Coconut oil has risen in popularity due to its culinary versatility and potential health benefits. It is extracted from the flesh of mature coconuts through gentler methods like cold-pressing or expeller-pressing, which preserve more of its natural compounds.

What makes coconut oil unique is its high content of medium-chain triglycerides (MCTs). These fats can be rapidly absorbed by the body and are linked to various benefits, such as aiding in weight management. For instance, research indicates that MCTs can boost metabolism by up to 12%. Whether used in baking, frying, or as a dairy-free alternative, coconut oil also adds a delicious flavor to recipes.

Understanding Your Choices

As we explore the spectrum of cooking oils, it becomes evident that knowledge about their origins, production methods, and health implications plays a crucial role in informed decision-making in the kitchen.

While oils like canola, vegetable, and corn oil are common in many households, they come with concerns related to their intensive processing, high omega-6 content, and potential for oxidation and trans fat formation. In contrast, extra virgin olive oil and coconut oil shine as healthier, less refined alternatives that enhance both flavor and nutritional value in your meals.

By paying attention to the types of cooking oils you use, you can create healthier and more delicious dishes that positively impact your overall well-being. Choosing oils that preserve their natural qualities can elevate your culinary creations and support a healthier lifestyle.

Do you read labels on the food you buy?