You may not have given much thought to seed oils, but they’re a big part of our daily diet, found in everything from frozen foods and bread to powdered milk and canned foods. Masu.
In fact, more than 25 percent of the calories in our diet come from eight types of seeds: rapeseed oil, sunflower, flaxseed, corn, grapeseed, soybean, rice bran, and safflower, according to a 2023 study published in the journal Nutrients. It comes from oil.
However, there are growing concerns that they may have a negative impact on our health. They are thought to increase inflammation and, as a result, are associated with diseases such as type 2 diabetes, heart disease, depression, and Alzheimer’s disease. And two new studies suggest that seed oils may be driving up cancer rates.
So how bad is seed oil? We spoke to experts to find out.
What is seed oil?
It is extracted from the seeds of plants that are dried, steamed, and then processed to release the oil. They contain high levels of omega-6 fatty acids.
The problem is that while mechanically pressing seed oil (literally squeezing the oil out of the seed) tends to preserve nutrients and flavor, it is difficult to produce oil on a larger scale and with a longer shelf life. More modern methods involve complex steps and the use of chemicals such as peroxide, which produce tasteless oils and toxic byproducts.
Seed oils are a cheap source of fat and are therefore widely used, especially in ultra-processed foods (UPFs), such as ready-to-eat foods.
Seed oils are a big part of our daily diet and can be found in everything from frozen foods and bread to powdered milk and canned foods.
Are they “bad” for you?
These two new studies are certainly concerning.
Researchers at the University of South Florida analyzed colon cancer tissue from 81 people and found that it contained large amounts of inflammatory omega-6, a tiny fatty compound that is produced when the body breaks down seed oils. It turned out that
These are thought to promote inflammation, help cancer grow, and prevent the body from fighting tumors.
Tim Yetman, professor of surgery and lead author of the study, told Good Health: “Eating too much omega-6 leads to too much pro-inflammatory lipids.” [i.e. fats] The influence of mediators creates an immunosuppressive environment in colon cancer. and I think it’s allowed [the cancer] To grow, thrive, and reproduce.
Another study published in Clinical Oncology found that men with early-stage prostate cancer who removed seed oils from their diets (including processed foods) and ate more omega-3-rich foods such as salmon. The disease was found to progress more slowly.
William Aronson, professor of urology at the University of California, Los Angeles and lead author of the study, said, “Simple adjustments to your diet can slow cancer growth until more aggressive intervention is needed. This suggests that the period may be extended.”
Is it associated with type 2 diabetes and dementia?
Increases in obesity and type 2 diabetes have been linked to increased intake of seed oils, while Sarah Berry, professor in the department of nutritional sciences at King’s College London, says that increasing amounts of processed foods in our diets suggests that this may be the actual cause. Cause.
“Many ultra-processed foods contain seed oils, which are lacking in nutrients while also containing high levels of sugar, salt and other additives,” she explains.
“Eating lots of ultra-processed foods containing seed oils may therefore be associated with an increased risk of obesity and other diseases, but the seed oils are not the culprit.”
When it comes to dementia, a new lab-based study shows that vegetable oils are more likely to cause plaque buildup in the brain than olive oil.
Dr Katherine Shanahan, a US physician and author of ‘Dark Calories: How Vegetable Oils Destroy Our Health And How We Can Get It Back’, who previously wrote for the Mail, said: ‘Vegetable oils can feel like a mist. , can make you feel tired, cause migraines, and in the future can cause diseases such as dementia.
“Vegetable oils cause oxidative stress, which damages membranes and causes plaque buildup in the brain.”
But is eating seeds bad for your health?
Omega-6s are beneficial and even essential for our health when consumed in adequate amounts. For example, linoleic acid, the most common form of omega-6 found in seed oils, helps maintain healthy skin and forms part of cell membranes.
“And there is evidence that people with higher intakes of linoleic acid have a lower risk of dying from heart disease,” Professor Berry told Good Health.
It is also thought to lower levels of “bad” cholesterol and improve blood sugar control. “Omega-6s are associated with a lower risk of developing diseases such as metabolic syndrome and type 2 diabetes,” she says, adding: It’s just too much that’s a problem.
Part of the reason is that linoleic acid is converted in the body to arachidonic acid, which promotes inflammation. “Many experiments have shown that arachidonic acid promotes obesity, inflammation and tumor growth,” Professor Yetman added.
Seed oil processing can also generate more toxins, he says.
More than 25 percent of the calories in our diet come from eight seed oils: rapeseed, sunflower, flaxseed, corn, grapeseed, soybean, rice bran, and safflower.
“Commercial processing may include bleaching and deodorization steps that degrade the seed oil and produce dangerous byproducts.”
The problem is that most people consume far more omega-6 than omega-3. The estimated ratio in the modern Western diet is approximately 16:1. This should be close to 1:1. If not, the argument is that this causes inflammation. body. However, this is not clear-cut.
Professor Berry says: “It’s perfectly fine to consume omega-6 as long as you’re getting adequate amounts of omega-3, and omega-6 has protective effects against many chronic diseases.”
Typically, a minimum of 250mg and up to 4,000mg of omega-3 is said to be beneficial.
Professor Yetman added that consuming seed oils in moderation is healthy. “I’m not demonizing seed oils,” he says. “But when you eat it in salad dressing for breakfast, lunch, and dinner, that amount adds up, and that’s the problem.”
He advises avoiding UPF and reading food labels.
Is it okay to cook with it at home?
Professor Yetman said heating seed oil to high temperatures, such as in deep-frying, can increase toxin levels.
Of particular concern, Shanahan said, is that heating seed oils to high temperatures and reusing them repeatedly can build up levels of toxic compounds.
“The basic problem with these oils is that they are very high in polyunsaturated fatty acids (PUFAs). These compounds tend to react with oxygen, a process called oxidation. ” This oxidation produces toxic new compounds called lipid oxidation products (LOPs).
“Toxicologists doing actual testing of vegetable oils in people’s homes and restaurants have found that even before cooking, the oils contain higher concentrations of toxins than when originally bottled. “Heating oil to make food creates even more toxins,” says Dr. Shanahan.
“Reheating” leftovers would produce even more toxins, she added.
Another concern is aldehydes. These are produced when seed oils are heated to high temperatures.
Martin Grootfeld, a professor of bioanalytical chemistry and chemical pathology at De Montfort University, has been studying the formation of aldehydes in heated seed oils for decades.
“Acrolein, the most toxic aldehyde, is more toxic than acrylamide,” he told Good Health.
“Everyone in the health and nutrition field took acrylamide and its toxicological properties very seriously, but very little was said about acrolein, a heated PUFA-derived product that causes lung irritation when inhaled. Not done.”
In 2019, he published a study in Nature showing that a 5-ounce serving of French fries cooked in vegetable oil contains 25 times the World Health Organization’s exposure limits for carcinogenic aldehydes.
Dr. Shanahan’s advice is to avoid fried foods when eating out.
Should I switch to olive oil?
Professor Yetman suggests using other oils high in omega-3s, such as olive oil or avocado oil.
“Olive oil has many proven health benefits and is a central component of the Mediterranean diet, which has consistently been shown to be the healthiest dietary pattern. It is effective for health etc.
You may have heard people talk about the “smoke point” of oils. During cooking, the oil begins to smoke, and the fatty acids it contains begin to break down, forming harmful compounds.
Professor Berry said there was a lot of misinformation about this, adding: “It is true that heating some cooking oils at high temperatures for long periods of time can produce compounds that are unhealthy.” I am.
“But in a home kitchen, this is not something to worry about. Reusing oil can have a similar effect, but you wouldn’t do it at home, and you wouldn’t do it in a restaurant either.” There is a law in place to do so.”
Dr. Shanahan argues that the edible oil industry has been “instilled with the false idea that in order for an oil to be suitable for cooking, it needs to have a high smoke point.” “Unfortunately, even though the oil has a high smoke point, the PUFA in the oil [‘natural’ vegetable] Petroleum…is invisibly broken down in harmful ways long before you start smoking it.
What about butter?
The British Heart Foundation’s current advice is that replacing saturated fats with unsaturated fats is better for your heart, saying: “One way to do this is by simply swapping butter spread for margarine spread.”
Other experts strongly disagree and are against processed oil.
Dr. Shanahan recommends butter, ghee, extra virgin olive oil or unfiltered refined olive oil, unrefined peanut oil, unrefined coconut oil, unrefined avocado oil, sesame oil, unrefined palm oil, bacon fat, They say you should use tallow, lard, chicken fat or unrefined oil. Nut oils (almond, hazelnut, pecan, etc.).
