What to know about seed oils: Myths debunked and recommendations
It seems like every week there's a new ingredient or subject being thrust into the internet spotlight with boastful claims of superb or detrimental health impacts stretching from social media feeds to scientific journals.
The latest buzzed-about topic, seed oils, is no exception.
Seed oils have cropped up as a heated topic of debate amid discussions surrounding the incoming Trump administration, which has tapped Robert F. Kennedy Jr. to lead the Department of Health and Human Services. Kennedy has voiced his intent to "Make America Healthy Again" if confirmed as HHS secretary, including cracking down on ultra-processed foods, many of which contain seed oils.
What are seed oils?
The vegetable oils extracted from the seeds of specific plants -- such as sunflower, grapeseed or safflower -- are commonly used in cooking, baking and processed foods alike.
Other seed oils across the category include canola -- which is a genetically modified version of rapeseed oil -- corn, cottonseed, soy and rice bran.
The calorie-dense ingredients can contain about 120 calories per tablespoon and are primarily composed of fats, including omega-6-rich polyunsaturated fats. Seed oils also contain small amounts of monounsaturated and saturated fats.
Some of the oils, such as sunflower, contain 5.6 milligrams of vitamin E per tablespoon.
Other seed oils like canola and soybean may also contain small amounts of omega-3 fatty acids.
Viral claims about seed oils
Social media wellness creators often post content about mass-produced seed oils, dubbing canola, corn, cottonseed, soybean, sunflower, safflower, grapeseed and rice bran oils as the "hateful eight" and toxic ingredients to stay far away from.
The various resounding online claims suggest that these oils in particular could contribute to inflammation, weaken the immune system and increase the risk of chronic illness. They reason that those oils are prone to breaking down into harmful compounds when exposed to heat, light or prolonged storage. Especially when cooking these oils at high temperatures, such as frying, the polyunsaturated fats in the seed oils can oxidize, producing compounds that may contribute to health issues.
Linoleic acid, an essential polyunsaturated fatty acid that's classified as an omega-6 fatty acid, is commonly found in seed oils, and according to Consumer Reports, many of those social media claims state that too much linoleic acid could promote chronic inflammation.
Critics of seed oils also argue that heat and solvents that can be used during the extraction process can create harmful chemicals and trans fats. However, experts say that the risk is relatively low, because oils are usually heated briefly and not at exceptionally high temperatures, which results in fewer trans fats than products like milk or butter.
Research and scientific studies on seed oils
Research has consistently shown that there is no increased heart disease risk from omega-6 intake and potential benefits for longevity. Additionally, the trace amounts found in seed oils are unlikely to harm health.
While studies are still limited, a randomized control trial on sunflower and rapeseed oil that was published in the European Journal of Nutrition in 2022 found no significant effect on heart or kidney disease markers in adults who were overweight or obese compared to their usual fat sources.
In 2019, researchers looked at a pooled global analysis of 30 studies and determined that linoleic and arachidonic acids levels did not raise the individuals' risk for heart disease.
Another study on linoleic acid published the year prior in The American Journal of Clinical Nutrition found that people with the highest blood levels of linoleic acid had a 43% lower risk of dying from any disease during the study period than those with the lowest levels of linoleic acid. Researchers also concluded that higher blood levels of arachidonic acid, another chemical related to the omega-6 fats found in seed oils, reduced the risk of death by 20%.
Expert recommendations for seed oil in your diet
Omega-6, including those from seed oil, are healthy fats that the human body needs, but can't produce itself, so they must be consumed from food. In moderate amounts omega-6 has been shown to help lower bad cholesterol and can reduce the risk of heart disease and stroke.
Excessive omega-6 intake, especially without enough omega-3s, which can come from fish, nuts and seeds, may promote inflammation that can negatively affect health.
The American Heart Association recommends getting 5% to 10% of daily calories from omega-6 fatty acids. For a 2,000-calorie diet, this equals 11 to 22 grams per day and between 100-200 calories.
Some valid concerns have bubbled up about seed oil consumption as it relates to bringing them to high temperatures that can cause a buildup of damaging chemicals. But experts note this is mainly a problem in commercial restaurants or factory deep fryers where oil is changed infrequently, as opposed to cooking at home.
Many commercially processed foods that use seed oils -- from snacks like protein bars to potato chips -- tend to be unhealthy for other reasons, experts note. Often, processed foods contain too many refined carbohydrates, as well as too much sodium, sugar and other unhealthy ingredients that are not part of a balanced diet.
