If you’ve spent any time on social media lately, you’ve probably heard that seed oils are toxic, inflammatory, and the root of all our health problems. Is this really true?
First: What are seed oils?
Seed oils are simply oils made by extracting oil from the seeds of plants. They’re commonly found in packaged foods and restaurant cooking, but also in ordinary cooking oils used at home.
Common examples include:
- Canola oil
- Soybean oil
- Sunflower oil
- Corn oil
- Peanut oil
- Grapeseed oil
Not every plant-based oil is a seed oil, as some oils are extracted from the fruit of the plant rather than the seed, such as olive oil and avocado oil.
Most seed oils contain primarily unsaturated fats, including monounsaturated and polyunsaturated fats. They also provide essential fatty acids, including omega-6 fatty acids and in some oils even omega-3 fatty acids.
Fiction: “Omega-6 fats cause inflammation.”
This is probably one of the most common things I’ve heard in the recent seed oil controversy.
Seed oils tend to contain omega-6 fatty acids, like linoleic acid. Both omega-6 and omega-3 fatty acids are essential fats, meaning our bodies can’t make them and we need to obtain them from food. You’ve likely heard all about how omega-3 fats can benefit your heart. Although omega-3 fats have well-established health benefits, most Americans don’t eat enough of them! (We do, however, eat plenty of omega-6 fats.)
Research shows that consuming typical amounts of omega-6 fats does not automatically cause inflammation, but eating only omega-6 fats without any omega-3s may increase metabolic disorders or inflammation. Rather than spending a lot of energy worrying about the omega-6 fats in seed oils, it’s better to make sure you are regularly eating omega-3-rich foods like salmon, sardines, walnuts, chia seeds, and flaxseeds.
While we’re on the topic of inflammation, an anti-inflammatory diet includes lots of fruit, vegetables, legumes, nuts, and whole grains, too!
Importantly, evidence supports the role of unsaturated fats, including seed oils, as part of a heart-healthy dietary pattern, particularly when they replace saturated fats.
Fact: The type of fat you replace matters.
Instead of asking, “Is this food healthy or unhealthy?”, we dietitians often ask a different question: “Compared to what?”
Replacing a food high in saturated fat with a source of unsaturated fat can be better for cardiovascular health. Seed oils are generally much lower in saturated fat than fats such as butter, lard and beef tallow. That doesn’t mean butter is “bad” or that you can never eat it – just that different fats have different benefits, and the overall pattern matters.
Another common social media claim is that Americans have had worsening health in recent decades alongside an increase in the intake of seed oils. While it’s true that Americans have been eating more seed oils, the increase has generally come from the increase in ultra-processed foods, which are frequently high in sodium, added sugar, and saturated fat and other ingredients of concern. It’s hard to place the blame squarely on seed oils alone!
Finally, some food companies are taking advantage of this controversy to sell you more of their food products! If an ultra-processed food like a cheesy cracker reformulates its recipe to swap out seed oils for a non-seed oil… does the new recipe of cheesy cracker become significantly healthier? Most dietitians would say “no”; the healthiness of the cheesy cracker is basically the same before and after reformulation – but that doesn’t stop the food companies from labelling the new crackers as “seed oil free” to try to convince you to buy more of it.
A Well Balanced Plate might still include those cheesy crackers on occasion, but will typically focus on a variety of fruits, vegetables, healthy proteins, whole grains, and legumes to nourish your body and mind.
Fiction: “Seed oils are toxic.”
There is a lot of scary language surrounding seed oils online, including claims that the extraction process makes them toxic. But the reality is much less dramatic.
Some seed oils are extracted using solvents, such as hexane, which is separated from the oil during processing. Although hexane can be harmful at high levels of exposure, that doesn’t mean that eating commercially produced seed oils exposes you to harmful amounts.
Seed oils may also go through refining processes that improve their flavor, stability, and shelf life. Refining can remove some naturally occurring compounds, such as polyphenols and tocopherols, but it doesn’t automatically make an oil toxic or unhealthy.
In other words, “processed” doesn’t automatically mean “dangerous.” Processing exists on a spectrum, and the fact that something has been processed doesn’t tell us everything we need to know about whether it’s nutritious or should be avoided.
So, should you avoid seed oils?
You don’t need to fear seed oils or eliminate every food that contains them to eat well!
Seed oils are not inherently toxic, and eating omega-6 fats does not automatically cause inflammation. Seed oils’ unsaturated fats can be part of a heart-healthy routine, particularly when they replace saturated fats. You certainly can choose to use less seed oil if you prefer olive oil or avocado oil for cooking – there’s nothing wrong with having preferences!
