Seed Oil: Study Links Omega-6s to Colon Cancer—What’s the Full Story?
New research links high levels of omega-6 fatty acids with colon cancer tumor growth.
Omega-6 fatty acids are also found in seed oils, which are abundant in ultraprocessed foods.
The study findings indicate that a specific type of food we eat may be to blame, not cooking oils specifically.
Seed oils have come under fire over the past few weeks with the nomination of Robert F. Kennedy Jr. as head of the U.S. Department of Health and Human Services. Kennedy has made his feelings about seed oils clear, suggesting that Americans are being “unknowingly poisoned” by them.
Now, new research published in the journal Gut found that ultraprocessed foods can cause inflammation in colon cancer tumors, suggesting that they may help fuel colon cancer. Some say this fuels the theory that seed oils, found in ultraprocessed foods, cause cancer, but that’s not what the study found. The findings do not say that seed oils cause colon cancer.
Meet the experts: Timothy Yeatman, M.D., study co-author and professor of surgery at the University of South Florida and Tampa General Hospital’s Cancer Institute; Wael Harb, M.D., a medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA; Anton Bilchik, M.D., Ph.D., surgical oncologist, chief of medicine and director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute in Santa Monica, CA
Here’s what the study findings do suggest, plus what cancer experts we spoke to recommend doing from here based on them.
What did the study find?
For the study, which was published in the journal Gut, researchers looked at the impact of fats (aka lipids) in the micro-environments around colon cancer tumors.
The researchers specifically looked at colon cancer tumors of 81 people with a tool called a mass spectrometer. That tool analyzed the types of lipid mediators (a type of fat that communicates between cells in the body, and that is mostly from the fats a person eats), along with how many were in the tumors.
The researchers determined that nearly all of the lipid mediators in the tumors were in a “pro-inflammatory” class of fats that includes omega-6 fatty acids. (Inflammation has been linked to certain cancers, including colon cancers.) The researchers also discovered that the lipid mediators suppressed the body’s immune response to the tumor.
Ultimately, the researchers concluded that eating ultraprocessed foods may fuel lipid mediators to suppress the immune system around tumors, fueling their growth. “Instead of fighting [tumor cells] off, they may be immunosuppressed or incapable of normal immune surveillance,” says Timothy Yeatman, M.D., study co-author and professor of surgery at the University of South Florida and Tampa General Hospital’s Cancer Institute.
Does this mean seed oils cause cancer?
No, this does not mean that seed oils cause cancer, Dr. Yeatman says. “But it suggests that omega-6s—prominent in seed oils—when taken in large daily amounts to the degree that they swap out the omega-3s in a 15-20:1 ratio, could induce a state of chronic inflammation and local immunosuppression,” he says.
The larger issue, as Dr. Yeatman explains, is that having too many omega-6 fatty acids in your diet and not enough anti-inflammatory omega-3 fatty acids may keep those omega-3s from doing their job (and, in this case, fighting tumors). This could allow tumor mutations “to take a foothold when otherwise they might be destroyed,” Dr. Yeatman says.
Ultimately, the problem is more about having too much processed food, says Anton Bilchik, M.D., Ph.D., surgical oncologist, chief of medicine and director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute in Santa Monica, CA. “There is emerging evidence that processed food increases the risk of colorectal cancer,” he says.
Wael Harb, M.D., a medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA, agrees, noting that there is “compelling evidence” that ultraprocessed foods may be linked to a higher risk of colon cancer, as well as a “diminished capacity for the body to combat the disease.”
But doctors stress that more than diet plays a role in whether someone will develop colon cancer. “Other factors such as genetic predisposition, family history, age, smoking, alcohol consumption, physical inactivity, and obesity also play crucial roles,” Dr. Harb says. Trying to lower your risk of developing colorectal cancer means looking at all of those areas, he says.
Are seed oils bad for you?
Not necessarily. The American Heart Association (AHA) maintains that seed oils can be a helpful part of your diet. In fact, the organization released a statement in 2017, noting that polyunsaturated fats like omega-6s help the body reduce the level of bad cholesterol, and lower the risk for heart disease and stroke.
A 2017 scientific analysis also determined that linoleic acid did not have a significant effect on inflammatory markers in the blood. And a study published in 2023 in the International Journal of Molecular Sciences found that people with higher levels of omega-6 fatty acids in their blood were more likely to have better cardiovascular health and glucose metabolism.
Yet another study, this one published in the British Journal of Nutrition found that linoleic acid may lower the risk of cardiovascular disease and type 2 diabetes.
What doctors suggest taking away from these findings
Ultimately, the cancer experts we spoke to say that doing your best to lower how much ultraprocessed food you have on a regular basis is never a bad thing. If you want to modify your diet to lower your your colorectal cancer risk, Dr. Harb suggests focusing on these foods:
vegetables
fruits
whole grains
legumes
nuts
lean proteins like fish and poultry
It’s also a good idea to limit how much you have of red and processed meats, along with sugary and ultraprocessed foods, Dr. Harb says. And, if you’re concerned about your omega-6 fatty acid intake, reducing that, along with increasing your intake of omega-3 fatty acids may also be helpful. That includes getting them from sources like anchovies, salmon, sea bass, bluefin tuna, and trout, along with oysters and mussels, per the AHA.
Of course, if you’re particularly concerned about your colorectal cancer risk or if you have a family history of the disease, it’s important to talk to a doctor for personalized recommendations on how to lower your risk, as well as potential increased or early screenings.
You Might Also Like
