Are Seed Oils Healthy? 

The group of oils known as seed oils has recently come under scrutiny in various online communities. Pointing to the processing they undergo and their fatty acid make-up, some people oppose the use of these oils—which include peanut oil, sesame seed oil, canola oil, soybean oil, and others—claiming that they are unhealthy. 

The truth, however, is more nuanced according to Dana-Farber dietitian Christina Conte, LDN, RDN.  

“What can be confusing is that seed oils are commonly used in ultra processed foods, fast foods, and deep-fried foods,” she explains. “Those sorts of foods are linked to increasing chronic disease risk. They tend to have more sodium, more unhealthy fats, more processed carbs.” 

On their own, though, seed oils are no more unhealthy than other cooking oils. “It’s more about the context that they’re being used in,” Conte says.  

In fact, she recommends using them over butter, lard, or coconut oil which have high concentrations of unhealthy saturated fats. For those who are concerned about maintaining heart health, which includes many people who have been treated for cancer, seed oils can be a useful ingredient. 

What are seed oils? 

The term seed oil references a range of cooking oils also known as vegetable oils that are made from the seed of a plant rather than the fruit. They include: 

• Canola oil 

• Peanut oil 

• Sesame oil 

• Rapeseed oil 

• Soybean oil 

They often have a neutral flavor, a high smoking point (the temperature at which they burn) and are ideal for cooking at high temperatures. Some of them also tend to be more affordable than other popular choices like olive and avocado oil. 

Are seed oils healthy? 

Dietitians like Conte recommend using seed oils over butter or lard while cooking. This comes down to the ratio of saturated to unsaturated fats in the oils. While unsaturated fats are linked to improved heart health and are important for a healthy diet, saturated fats raise unhealthy LDL cholesterol. In moderation, oils with a higher level of unsaturated fats like olive, avocado, and even seed oils will be better for your heart health than butter, lard, or coconut oil. 

 It is important to remember that, while our bodies need fats, they should be consumed in moderation.  

Opponents of seed oils say that their fatty acid make-up is detrimental to health. Many of these types of oils have a higher ratio of omega-6 fatty acid than omega-3, and omega-6 has been linked to inflammation.  

“You could see how this would raise concern,” Conte says. “But this is an extrapolation that is not currently supported by strong evidence, especially when these oils are consumed in moderation.” Researchers who have studied this question have not found evidence that the levels present in seed oils are concerning. 

In some cases, even the opposite is true. Canola oil is an excellent vegetarian source of omega-3 fatty acids which may support heart health. 

Are seed oils connected to cancer? 

Research has not found a link between seed oils and cancer. Conte even recommends that some people undergoing treatment replace butter and lard with seed oils like canola oil. 

Some people have raised concerns about the extraction process for making these oils. In some cases, companies use chemicals like hexane which is known to be toxic in gas form. “This fact is cherry picked,” Conte says.   

In this process, hexane is used in a liquid form rather than gas. Only trace amounts, if any, remain in the oil itself. Compared to other daily exposures, like gasoline fumes, the level of exposure would be much lower.    

Should I avoid seed oils? 

The bottom line is that seed oils are safe to use for cooking, and dietitians recommend them over animal fats like butter or lard. Avocado and olive oil are also healthy cooking oils.  

If you are concerned about seed oils in your diet, the first thing you can do is cut back on ultra-processed foods. “Overall, this would be a big health win,” Conte says. “Whole foods will always be more nutritious.”