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Steak ‘n Shake recently announced it plans to transition from seed oils to butter and beef tallow—a move they referred to as “RFK’ing the fries.” Many other restaurants plan to follow suit due to growing populist criticism and curiosity about seed oils, driven by online influencers and, more recently, Secretary Kennedy.
This contradicts traditional health advice, which recommends limiting saturated fats (such as butter and beef tallow) and replacing them with unsaturated fats, like those found in oils and seeds.
So, what’s really going on with seed oils?
Thanks to the thousands of you who submitted questions on YLE platforms—this post is driven by your curiosity. I hope it helps spark conversations, guide evidence-based decisions, and satisfy some of the questions you’ve been holding onto.
What are seed oils?
Seed oils are extracted from the seeds of plants—like soybeans, canola, corn, sunflower, cottonseed, grapeseed, safflower, and rice bran. This includes vegetable oil blends. In contrast, oils like olive, coconut, palm, and avocado are extracted from fruits, not seeds.
Seed oils are high in unsaturated fat—a type of fat that’s typically liquid at room temperature and also found in fish, avocados, nuts and seeds. These are different from saturated fats, which are typically solid at room temperature and found in animal-based foods, such as meat and dairy, as well as in tropical oils like coconut and palm.
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Photo: Getty Images.
Are seed oils healthy?
Yes—as a part of a healthy diet.
Seed oils are particularly high in polyunsaturated fats (PUFAs) that are important for heart health, cell function, metabolism, immune regulation, and even brain health. Specifically, they offer linoleic acid, an essential omega-6 PUFA that our bodies can’t make on their own, so we have to get it from food.
A large body of evidence supports the health benefits of unsaturated fats, particularly when they replace saturated fat. This protective effect is driven mostly by reducing LDL (“bad”) cholesterol and triglyceride levels.
- A meta-analysis from the American Heart Association found that replacing saturated fat with vegetable oil PUFAs reduced the risk of heart disease by 30%, similar to the effect of statins.
- A study of 400,000+ adults found that higher intake of plant-based fats lowered the risk of death from heart disease by 15–30%.
- A 33-year study of 220,000 adults found that replacing one tablespoon of butter with a plant-based oil reduced the risk of all-cause and cancer-related death by 17%.
To be clear, some newer research is revisiting the role of saturated fats—particularly in whole foods like dairy, unprocessed meat and dark chocolate. But that doesn’t mean seed oils are harmful. Both types of fat can fit into a healthy and balanced diet.
So, why the backlash?
Critics call seed oils “toxic” or “poisonous” and blame them for the rise in chronic disease. Here’s what’s driving the backlash:
- Correlation ≠ causation
Yes, seed oil consumption has increased. So has obesity. However, both saturated and unsaturated fats are prevalent in ultra-processed foods, which now account for more than half of American calories. So, is it seed oils—or the ultra-processed foods they’re in? Chronic disease is complex, and no single ingredient is solely to blame.
- Omega-6 fats, inflammation, and balance
Seed oils contain linoleic acid, an omega-6 fatty acid, which can convert to arachidonic acid—a fatty acid involved in inflammation. However, research shows dietary linoleic acid does not significantly raise arachidonic acid levels or most markers of inflammation. Some studies suggest it may have anti-inflammatory properties. Additionally, we obtain most of our arachidonic acid from consuming animal-based foods, such as chicken, eggs, and beef, rather than from seed oils.
The other concern is that we are eating too many omega-6s and not enough omega-3s (which can be found in fatty fish, walnuts and flaxseed, for example) This concern is valid. Our intake of omega-6s has increased, while omega-3s remain too low. This shift in ratio may have health implications—but the clinical significance of the ratio itself is still debated. Regardless, most experts agree: the key is not to fear omega-6s, but to boost omega-3 intake.
- Processing and hexane
Like many things in our diet, seed oils require processing. Seed oils can be extracted using a liquid called hexane, which facilitates efficient separation of the oil from the seed. While trace amounts of hexane can remain, these levels are extremely low—much less than what we’re exposed to from air pollution. The refining process, which includes bleaching and deodorizing, strips away some nutrients but also improves shelf life and increases smoke points—important for maintaining stability during cooking. Cold-pressed oils are less processed options, but they’re more expensive and less stable.
- Conflicting evidence
Science is constantly evolving, and challenging conventional wisdom is healthy. But not all studies are created equal.
- Consider the Minnesota Coronary Experiment of the 1960s, which found that while vegetable oils lowered LDL cholesterol, they did not improve health outcomes. However, the study had serious flaws: high dropout rates, incomplete data, and limited generalizability. It’s one data point—not a reason to overturn decades of evidence.
- A more recent study linked inflammation in colon cancer to higher levels of arachidonic acid. Headlines were quick to point to seed oils as a culprit, but the study was observational, didn’t include any dietary data, and cannot imply a cause-and-effect relationship. It highlights a potential biological mechanism—not a reason to overhaul public health guidelines.
Follow the money
There’s also a booming wellness market that profits from fear. Valued at over $1 trillion, the industry is filled with influencers who demonize seed oils while selling products they claim will “reverse” the damage—like omega-3 supplements, antioxidants, or detox kits. Others push their own premium, seed-oil-free alternatives, including avocado oil, olive oil, or so-called “ancestral fats” like beef tallow and butter blends.
Examples:
- Mark Hyman, a physician and influencer, advises people to avoid seed oils and offers lab test memberships to help determine if their omega ratios are imbalanced.
- Mark Sisson, a fitness and food writer, founded Primal Kitchen—a seed oil-free brand of mayonnaise and salad dressings—and later sold it to Kraft Heinz for $200 million.
- Carnivore MD (Paul Saladino) frequently criticizes seed oils while promoting high-end, animal-based supplements.
Where does this leave us?
Seed oils can complement a healthy diet, providing essential omega-6 PUFAs, and are useful for cooking, baking, and dressings.
Avoiding seed oils alone isn’t necessarily harmful (we get plenty of these fats from grains, then meat, fats and nuts).
However, there can be unintended consequences, such as replacing seed oil with refined saturated fats like butter, lard and beef tallow (different from the aforementioned whole food sources that may have a beneficial “food matrix”). These trending swaps can be detrimental, as they raise LDL cholesterol and increase the risk of heart disease. There are also real cost implications for many Americans (see more below in the FAQ.) and unnecessary fear is not healthy either.
Ultimately, the seed oil debate reveals a deeper issue with how we talk about nutrition.
We tend to fixate on single ingredients or nutrients—such as seed oils, gluten, carbs, and fats—while ignoring the complexity of whole foods and the broader picture of overall diet quality, which matters far more.
That’s why initiatives like Food Is Medicine are so promising. They focus on promoting healthy eating patterns—integrating access, education, healthcare, culture and policy —without allegiance to any specific diets or ideology.
Bottom line
From a public health perspective, we do have room for improvement in our diets, but removing seed oils is far from the top of the priority list.
Seed oils are not miracle cures, and they’re not poison.
Like most things in nutrition, context is everything.
What matters most is your overall dietary pattern—diverse, nutrient-rich, and mostly minimally processed.
Demonizing seed oils oversimplifies the science and distracts from the real underlying issues in our food system.
