The Truth About Seed Oils, According to MSK

Are seed oils harmful? Social media trends and wellness influencers often say yes. Some restaurants now advertise seed oil–free menus. The new federal dietary guidelines, known as the Food Pyramid, suggest using fats other than seed oils, such as butter and beef tallow.  

So what does the science about seed oils really show? Members of the registered dietitian-nutritionist team at Memorial Sloan Kettering Cancer Center (MSK) say seed oils are actually an important part of a healthy diet.  

“The scientific literature strongly supports incorporating seed oils into a well-balanced diet,” says MSK clinical dietitian Michelle Myers, MS, RDN, CSO, CDN. “They provide essential fatty acids the body cannot produce on its own, and when consumed in typical amounts, they’re both safe and beneficial.” 

What are seed oils?  

Seed oils are fats taken from plant seeds. Seed oils often were called vegetable oils in the past. The most common seed oils come from canola, corn, cottonseed, soybean, sunflower, safflower, grapeseed, and rice bran.  

Other vegetable oils, such as olive oil and avocado oil, are not seed oils. They’re made from the pulp of the fruit, not the seed.  

How did seed oils get a bad reputation? 

In recent decades, experts have linked having many highly processed foods to a rise in obesity and health problems, including some cancers. Highly processed foods have a lot of seed oils, and some people suggest the oils themselves may have caused the surge in health problems. Some people have also proposed that a specific type of fat in seed oils may cause more inflammation in the body. 

What is the role of seed oils in ultra-processed foods?   

Ultra-processed foods often have ingredients that someone cooking at home would not use. Examples of ultra-processed foods include many cereals, crackers, packaged baked goods, and meat substitutes. They also include sugary drinks, candy, and fast food.  

“A helpful way to spot ultra-processed foods is by checking the ingredient list,” Myers says. “If you see a long list with additives like emulsifiers, stabilizers, artificial flavors, or preservatives, the food is likely ultra-processed. These are ingredients you wouldn’t usually use in home cooking.” 

Seed oils often are used in ultra-processed foods because they’re cheap and don’t change the flavor of other ingredients. 

“We know if you eat a diet high in ultra-processed foods, you’re likely eating more seed oils,” says MSK clinical dietitian Elissa Meditz, MS, RDN, CSO, CDN. “But seed oils are not the reason ultra-processed foods should be limited or avoided in someone’s diet. Ultra-processed foods are often high in calories and contain high amounts of saturated fats, sodium, and sugar. They contain low amounts of healthful nutrients such as fiber.” 

Why are seed oils important for good health?  

Seed oils are high in a type of fat called omega-6 polyunsaturated fatty acids, including a fatty acid called linoleic acid.   

Linoleic acid is an essential nutrient. Our bodies can’t make linoleic acid on our own, so we must add it to our diet. It’s harmful to have no linoleic acid at all. Having too little linoleic acid can cause skin problems, hair loss, and stunted growth in children. 

People worried about seed oil argue linoleic acid breaks down to arachidonic acid, another fatty acid that causes inflammation. But research shows only a very small amount of linoleic acid (0.2%) becomes arachidonic acid.   

“Inflammation has become a buzzword, but its connection to health is complicated,” Meditz says. “Also, it’s important to note that there’s no evidence of increased inflammation in people who eat typical amounts of seed oils.”  

A 2025 study published in the journal Nutrients found no connection between levels of linoleic acid in the blood and markers for inflammation. The study included almost 3,000 people.  

Why are seed oils healthier than animal fats? 

Seed oils are lower in saturated fat. That’s the biggest difference between seed oils and animal fats such as butter, lard, and beef tallow.  

Saturated fat molecules have more hydrogen atoms, which makes these fats solid at room temperature. Saturated fat can make cholesterol build up in your blood vessels, raising your risk for heart disease, stroke, and other health problems. 

You can lower these health risks by replacing saturated fats with unsaturated fats, like seed oils. A study published in JAMA Internal Medicine in 2025 compared people with the highest and lowest levels of seed oils in their diets. People who consumed the highest levels of seed oils were 16% less likely to die than people with low levels. 

Swapping about 2 teaspoons of butter for seed oil each day also lowered their chances of dying from cancer: Replacing 10 grams of butter with the same amount of seed oil lowered the risk by 17%.  

“The scientific literature supports incorporating seed oils into a well-balanced diet, particularly when they replace sources of saturated fat,” Myers says. “The majority of peer-reviewed research does not support concerns about seed oils when consumed in typical dietary amounts.” 

It’s important to note that seed oils in ultra-processed foods are often hydrogenated, which means chemical changes make them behave more like saturated fats. Hydrogenated oils are less healthy than seed oils in their natural liquid form. Try to avoid hydrogenated oils, just like other saturated fats.  

What diet do MSK experts recommend for people concerned about cancer? 

“Plant-based diets have the most scientific support for promoting good health, so we encourage our patients to follow recommendations for plant-based eating as much as they can,” Meditz says. “This doesn’t mean you have to be vegetarian or vegan. The goal is for at least two-thirds of the foods you eat to come from plants and one-third to come from animal products.”

Meditz says examples of plant foods include fruits, vegetables, whole grains, beans, legumes, nuts, and seeds. “For those who choose to consume animal products, we recommend choosing lean sources, such as poultry or fish, most often rather than red and processed meats,” she adds.  

“When a diet goes viral or starts trending on TikTok, it may grab people’s attention, but it can also spread misinformation,” Myers says. “Telling people to eat a balanced diet is not going to sound exciting, but it’s what’s essential for good health.” 

“We want MSK patients to know that our clinical dietitians are available to provide science-based guidance and answer any questions that they may have,” says Christina Stella, MS, RDN, CDCES, CSO, CDN, a Clinical Nutrition Manager.