Vegetable oils, derived from seeds, nuts, and some fruits, are commonly used in cooking and baking. While some may offer health benefits, there’s ongoing debate about whether others are good for you.
Vegetable oils are extracted from the seeds, nuts, or fruit of plants. The majority of vegetable oils are produced using chemical extraction, although some oils are extracted using modern equipment that presses the juice or utilizes heat to extract the oil.
Types of vegetable oils include soybean oil, safflower oil, and canola oil. Oils from fruits, like olive oil and avocado oil, are sometimes considered types of vegetable oil, even though they’re technically fruit oils.
Different types of vegetable oils have different nutritional compositions and can have different effects on your health. This largely depends on the types of fat they contain.
Types of Fats
- Saturated fats: Found mostly in animal fats (like butter) and tropical oils (like coconut and palm oil), saturated fats are solid at room temperature. Diets high in saturated fat can increase bad (LDL) cholesterol levels in your blood, increasing the risk for heart disease.
- Trans fats: These fats are artificially created by hydrogenating oils to make them more solid. They are often found in ultra-processed foods like frozen pizza, cookies, and biscuits. Trans fats have been linked to an increase in LDL cholesterol and a decrease in good (HDL) cholesterol. They are also associated with a higher risk of type 2 diabetes.
- Monounsaturated fats (MUFA): Found in olive oil, avocado oil, safflower oil, and canola oil, monounsaturated fats help lower LDL cholesterol and may improve heart health.
- Polyunsaturated fats (PUFA): These fats include omega-3 and omega-6 fatty acids, which are essential for many functions in the body. Polyunsaturated fats also help reduce LDL cholesterol. Sources include sunflower, canola, corn, and soybean oil.
Vegetable oils are often considered heart-healthy. Research shows that replacing saturated fats with vegetable oils rich in MUFA and PUFA can lower cholesterol and reduce the risk of heart disease in both healthy and at-risk adults.
Unrefined vegetable oils, such as cold-pressed olive oil, also contain beneficial plant compounds like antioxidants that can protect against cell damage.
Some of the best oils for health include:
- Extra virgin olive oil: The antioxidants and monounsaturated fats in olive oil, especially oleic acid, support heart health and may help lower the risk of heart disease. Extra virgin olive oil is generally the healthiest oil to cook with. It is made without heat or chemicals, so it retains its full range of natural antioxidants and polyphenols.
- Avocado oil: Similar to olive oil, avocado oil is high in heart-healthy monounsaturated fats like oleic acid, has a mild flavor, and is rich in antioxidants. Cold-pressed avocado oil retains the most nutrients and beneficial compounds.
- Canola oil: Canola oil is a seed oil that contains monounsaturated fats and some heart-healthy omega-3 fats. However, most commercially produced canola oil is extracted using a chemical solvent called hexane, and the process often involves the use of heat. This may reduce some of its beneficial compounds. For the most potential health benefits, look for unheated and unrefined canola oil.
While vegetable oils can be healthy in moderation, there are some concerns about potential negative health consequences.
Too Much Omega-6 and Inflammation
Most refined vegetable oils are high in polyunsaturated fats, especially omega-6, while having less omega-3. Both types are needed in your diet, but eating too much omega-6 compared to omega-3 may promote inflammation.
The Western diet tends to have a very high omega-6 to omega-3 ratio, which some studies suggest may create a pro-inflammatory environment that contributes to chronic diseases. If you use vegetable oils, eating more fatty fish, flaxseeds, and chia seeds can help balance this ratio by providing more omega-3s.
You can also opt for oils like olive and avocado oil, which are lower in omega-6 fats and higher in monounsaturated fat.
Oxidation and Free Radicals
When vegetable oils high in omega-6 fats are repeatedly heated to high temperatures, like during frying, they can oxidize. Oxidized oils produce compounds called free radicals, which can damage cells and contribute to inflammation and disease.
Rather than just focusing on smoke point, research suggests that fatty acid composition, natural antioxidants, and the level of refining are more important. A study highlighted that extra virgin olive oil, with its low polyunsaturated fat content and unrefined nature, can be suitable for use in high-heat cooking.
Trans Fats and Hydrogenation
Some vegetable oils are partially hydrogenated to make them more solid, which creates harmful trans fats. Although trans fats have largely been removed from the food supply in the United States, some imported or processed foods may still contain them.
Avoid products with “partially hydrogenated oils” on the label.
Here are some simple tips to make healthier choices with vegetable oils:
- Choose minimally processed oils: Opt for extra virgin olive oil, avocado oil, or unrefined oils when possible. These retain more health-promoting nutrients and are often linked with lower levels of inflammation.
- Balance omega-6 and omega-3 fats: Swap oils high in omega-6 for avocado or olive oil, which are lower in omega-6. Also, include more omega-3-rich foods like salmon, walnuts, and flaxseeds in your diet.
- Limit fried and processed foods: Many packaged and ultra-processed foods are prepared in refined vegetable oils. These foods also often contain added sugar, high amounts of sodium, and high-fructose corn syrup, which can contribute to chronic disease when consumed in excess.
- Store oils properly: Keep oils in a cool, dark place and tightly sealed to prevent oxidation. Throw away oils once they are past their expiration date.
- Include in moderation: Even healthy oils are high in calories. Use them in moderation as part of a balanced diet that includes lean protein, fruits and vegetables, other healthy fats, and whole grains.
Vegetable oils are a source of unsaturated fats, which have been shown to benefit heart health when used in place of saturated fats. However, consuming too many highly processed oils high in omega-6 fats may have downsides, though more research is needed.
Until we have more research, choosing minimally processed vegetable oils, adding more omega-3 fats to your diet, and avoiding fried and processed foods are safe steps you can take to improve your health.
