What Are Seed Oils? Here’s What Science Has to Say

If you’re interested in food and on social media, you’ve probably seen a lot of posts mentioning “seed oils,” which critics claim can contribute to obesity, heart disease and cancer. In fact, seed oil opposition was part of the platform of 2024 presidential candidate, and current Secretary of Health and Human Services, Robert F. Kennedy, Jr., who posted on X that we needed to return to using beef tallow on french fries to avoid “being unknowingly poisoned by heavily subsidized seed oils.” However, others say that seed oils, while not particularly healthy, are still healthier than cooking with meat-based products like lard or tallow. 

If you’re still trying to figure out exactly what seed oils are—and if you should avoid them—we’ve put together this handy guide to cut through some of the debate. 

What are seed oils? 

Seed oils are basically any type of vegetable oil that’s derived from the seed of a plant, rather than its fruit. There are eight main types of seed oils that are on the market:

• corn oil
• cottonseed oil
• grapeseed oil 
• canola oil (also known as rapeseed oil) 
• sunflower oil
• soybean oil
• safflower oil
• peanut oil
• rice bran oil 

What’s the difference between “seed oils” and “vegetable oils?”

There isn’t one, really. All seed oils are vegetable oils, and many of them are marketed under that name. Although, we should mention that not all vegetable oils are seed oils, as many popular oils like olive oil, avocado oil, and palm oils don’t come from seeds. 

So, why are people concerned about seed oils but not other vegetable oils? 

The biggest complaint most have against seed oils is how they’re processed, as refined oils (which also includes plenty of non-seed oils) often use solvents to extract the flavor of the oils and refine it for market. And while these solvents are not present in the final product, many are worried about their use in any food. 

However, government and safety organizations argue that those solvents do not result in any danger to consumers. And there are also other refining methods you can choose from, like cold-pressing. (Although, those oils are often more expensive.) 

Also, seed oils tend to get used in ultraprocessed foods, which are often fried in oil and also high in unhealthy ingredients like salt, sugar, and saturated fat. But that doesn’t mean that seed oils are to blame for health problems. 

Do seed oils cause inflammation? 

Another common criticism of seed oils is that they cause inflammation and constrict blood vessels, but there’s no evidence to support that. It’s often claimed that the Omega 6 fatty acids in seed oils are to blame for this, but those fatty acids actually help prevent that kind of cardio-vascular inflammation. It’s just that the most well-known Omega 3 fatty acids (often found in fish and plants) fight it even more. And over the years, that fact has been twisted into saying that Omega 6s are bad for inflammation, instead of just not being as effective as Omega 3s. 

Are seed oils healthier than cooking with meat products? 

According to the FDA, yeah. It’s easy to forget, but before vegetable oils became popular, most foods were fried in beef tallow or fat, which are very high in saturated fats that increase cholesterol. Vegetable oils are high in unsaturated fats, which can lower cholesterol. However, the concerns about seed oils have many people advocating for a return to beef products, which are undoubtedly higher in saturated fats and trans fats. But we have decades of research showing the dangers of a diet high in saturated fats, as opposed to the unsaturated fats you find in seed oils.