Seed oils, commonly known as vegetable oils, are a staple in most diets. People often cook with seed oils, which can also be found in snack foods, restaurant meals, and even baby formula.
Seed oils, such as soybean and canola, tend to get a bad rap, but do you really need to avoid these popular fat sources for optimal health?
Seed oils are oils extracted from seeds of plants such as corn, soybean, and canola.
Seed oils are obtained either through mechanical or chemical extraction. Mechanical extraction involves crushing the seeds to get their oil. Chemical extraction involves using a solvent, like hexane, to extract the oil from the seeds.
After extraction, most vegetable oils undergo a refining process, including bleaching and deodorizing. The oil is exposed to high temperatures to create a final product that’s neutral in color and taste and resistant to going bad. This is why refined seed oils are known as “RBD” oils, which stand for refined, bleached, and deodorized.
There are several seed oils used in everyday cooking and food production. Some of the most common types include:
- Soybean oil: Soybean oil is derived from soybeans and is the most common vegetable oil in United States diets.
- Canola oil: Canola oil is derived from the seeds of the canola (rapeseed) plant.
- Corn oil: Corn oil is derived from corn kernels. It is commonly used in commercial food production and deep-frying.
- Safflower oil: Safflower oil is derived from the seeds of the safflower plant. It’s used in home cooking and is popular in products like salad dressings and snack foods.
- Sunflower oil: Sunflower oil is derived from sunflower seeds, and it’s used in cooking, commercial food production, and skincare products.
Oils from canola, soybeans, and sunflower seeds make up 87% of global vegetable oil production.
Seed oils are commonly used in home cooking methods such as pan-frying, baking, and sauteing. They’re also used in restaurants, fast-food establishments, and commercial food production.
Though seed oils aren’t inherently harmful to your health, there are potential health concerns if consumed regularly.
Seed oils are rich in omega-6 fats necessary for brain function, growth, and development. While your body needs omega-6 and omega-3 fats, most people consume too many omega-6 fats and too few omega-3 fats.
The average diet in the U.S. contains up to 20 times more omega-6 fatty acids than omega-3s. While there’s no consensus on the ideal omega-6 to omega-3 ratio, experts believe it should be between 1:1 and 4:1 for optimal health.
Consuming a diet too high in omega-6s and too low in omega-3s promotes inflammation and may increase the risk of several health conditions, such as type 2 diabetes and heart disease. Most people could benefit from increasing their intake of foods high in omega-3 fats, like seafood, and decreasing their intake of omega-6-rich foods, like seed oils.
Seed oils are highly refined and prone to oxidation at high temperatures. They are commonly used for frying but are high in polyunsaturated fats, which are unstable at high temperatures and prone to oxidation. Oxidation occurs when fats break down and form harmful compounds like trans fats and free radicals.
Free radicals are highly reactive and can damage cells and increase inflammation. Trans fats have been shown to negatively affect health and increase the risk of heart disease. One study found that repeatedly heating canola oil increased the amount of trans fats in the oil by 233%.
Seed oils repeatedly heated, such as those used to deep fry foods like French fries, are especially prone to oxidation. Eating foods fried in seed oils regularly may increase the risk of several diseases, including heart disease and cancer.
The refining process used to make seed oils strips them of beneficial compounds, such as polyphenol antioxidants and vitamin E, making them less nutritious than unrefined oils like cold-pressed olive oil.
While overconsumption of seed oils could have negative health effects, there’s no reason to avoid them completely. In fact, some research suggests that certain seed oils may offer some benefits.
Seed oils are affordable, which is why they’re often used in commercial food production and restaurants. People on a budget may prefer using seed oils over more expensive fats like olive oil and avocado oil.
Seed oils are a source of essential nutrients, such as vitamin E. One tablespoon of canola oil provides 2.42 milligrams of vitamin E, which is 16% of the Daily Value (DV). The same serving of sunflower oil provides 37% of the DV.
Vitamin E is an antioxidant that protects against cellular damage by neutralizing reactive compounds called free radicals. Vitamin E is also important for immunity, blood clotting, and other bodily processes.
Most people in the U.S. don’t get enough vitamin E through their diets. Studies show that around 90% of men and 96% of women in the U.S. don’t consume enough vitamin E.
Research suggests that up to 32% of vitamin E is removed from seed oils during the refining process. Choosing unrefined oils, such as cold-pressed sunflower oil, can reduce this nutrient loss.
Unrefined vegetable oils contain other antioxidants, such as carotenoids and phenolic compounds. These can protect against cellular damage that can lead to disease. One study found that replacing butter with canola, corn, or olive oil was associated with lower total and heart disease-related mortality.
Some research suggests that certain seed oils may offer other benefits, such as protecting against obesity. More studies are needed to understand fully how consuming vegetable oils impacts overall health.
Many seed oils have a high smoke point, which is the temperature at which an oil starts to smoke. Canola oil has a smoke point of around 400 degrees Fahrenheit (204 degrees Celsius), making it a good choice for high-heat cooking.
Keep in mind that repeatedly heating seed oils, such as in deep-fat frying, leads to the formation of harmful compounds like trans fats and free radicals.
Seed oils can be part of a well-rounded diet when consumed in moderation. Seed oils have many uses in the kitchen, whether for cooking or baking.
Here are a few ways to use seed oils:
- Use seed oils with a high smoke point for high-heat cooking methods
- Use seed oils to make salad dressings and marinades
- Use seed oils, like canola oil, when baking cakes, cookies, and brownies
- Substitute in seed oils if you run out of butter, olive oil, or coconut oil while cooking or baking
When possible, choose unrefined seed oils—such as cold-pressed seed oils—over refined seed oils. Unrefined seed oils are higher in protective compounds, such as vitamin E and carotenoid antioxidants, making them a healthier overall choice.
If you’re trying to reduce your seed oil consumption, there are plenty of healthier swaps, like olive oil and avocado oil.
Olive oil is packed with protective nutrients and plant compounds, such as vitamin E and polyphenols. Virgin olive oils, including extra-virgin olive oil (EVOO), are healthier choices than refined olive oil because they contain more protective compounds, such as polyphenol antioxidants.
Olive oil is more flavorful than seed oils like canola oil. Its taste is often described as grassy, buttery, and peppery. When using olive oil in place of seed oils, you’ll need to account for the taste differences.
Avocado oil is also an excellent substitute for seed oils since it has a mild taste that won’t overpower dishes. It’s high in vitamin E and antioxidant plant compounds like polyphenols and carotenoids.
Seed oils are oils extracted from the seeds of plants, including soybeans, canola, and corn.
Seed oils offer some benefits, such as providing a source of vitamin E. However, they’re best consumed in moderation since most are highly refined and are high in omega-6 fats.
To promote overall health, try consuming various healthy fats, such as oils, avocados, nuts, seeds, and full-fat yogurt.
