Seed oils and colon cancer?🔥
Did you read the headlines last week about seed oils and colon cancer? Fact or fiction? Let’s dig into the science of cooking oils and untangle the confusion
What Are Seed Oils?
Seed oils—like canola, sunflower, soybean, corn, safflower, sesame, and peanut oil—are, yep, you guessed it, extracted from seeds. But let’s not lump all seed oils into one bucket - the way they are extracted can make a difference:
High heat, pressure, and chemical solvents (like hexane): This refining process strips beneficial compounds like vitamin E and may even introduce trace amounts of solvents like hexane, although these amounts are tiny and unlikely to pose a health risk at amounts used for normal cooking.
Cold pressing: A gentler method where oil is mechanically squeezed out of seeds without heat or chemicals. This process retains more nutrients and produces higher-quality oil with fewer contaminants 🌱.
Why Are Seed Oils So Widely Demonized?
Seed oils are often high in omega-6 fatty acids—a type of polyunsaturated fat that’s essential for health (yes, your body needs it). The controversy? Omega-6 fats can become problematic when consumed excessively, especially relative to omega-3s.
Think of omega-6 and omega-3 as competitive siblings vying for your body’s attention. To keep things balanced, the ideal omega-3 to omega-6 ratio is about 1:2 or 1:3.1 Unfortunately, Western diets skew this balance dramatically—closer to 1:20—thanks to the overconsumption of ultra-processed foods and insufficient omega-3 intake.
Omega-6 fats alone aren’t inherently inflammatory. The issue lies with the overall dietary imbalance of omega-6 to 3. This is why I had to get off Instagram for my sanity - social media posts lack nuance because the algorithm pushes sensationalized headlines…
Don’t Fall for the Headlines
Last week’s news headlines really outdid themselves 🫣 with “Seed oils may be linked to increased colon cancer in young people!” Honestly, I’m still picking up pieces of my brain from how far they stretched this one. Classic case of media doing mental gymnastics for clicks.
Let’s break it down. This was the headline.
What they wrote in the article:
This is utter rubbish - for lack of a better word 🤭. The paper they linked to did not even name seed oils as a contributing factor. And yet right away, we saw social media influencers jump on the bandwagon without even checking what the paper ACTUALLY said (Can you see why I needed a social media break? And why I’m so grateful to have you here 👯♀️?)
Here’s what it said instead ⬇️.
The Actual Study
Researchers2 looked at 81 colorectal cancer tumor samples and analyzed:
The fat (lipid) composition of the cell membranes,
Gene expression in the tumor cells that controlled inflammation
The tumor microenvironment (i.e., the tissue around the tumor).
Here’s what they found:
Increased arachidonic acid (AA)-derived pro-inflammatory lipids in the tumor cells,
Inflammatory genes are upregulated,
Chronic inflammation in the tumor environment.
Translated into English: they found inflammatory lipids (fats) in the tumor cells, the genes that control inflammation were ramped up, and there was chronic inflammation in the tissue surrounding the tumor cells.
Is that even surprising to you? I mean, we KNOW that chronic inflammation is a breeding ground for cancer - so these findings are in keeping with what we already know.
But here’s the problem I have with the news headlines.
Nowhere in the paper did they suggest that seed oils were the culprits. In fact, they did not even know if the patients from whom the tumor samples came from even consumed seed oils - or what their diet was like…
What the paper hypothesized, was the “Western diet – low in fiber, high in omega-6 fatty acids like linolenic acid (LA)” – is linked to chronic inflammation and colorectal cancer.
Where is the biggest source of omega-6 fatty acids in the Western diet? Ultra-processed foods!!
A more accurate headline would be:
📰 “Ultra-processed foods could be causing colon cancer surge in young people” — because these foods embody the “low fiber, high omega-6” diet the study referenced.
The Science They Ignored:
Yes, inflammatory mediators (the chemical messengers that stir up inflammation) are made from omega-6 fatty acids (like LA).
But if there is only ONE thing you take away from this article, let it be this.
Saying “eating omega-6 fats = more inflammation” is like saying “having flour in your pantry = automatic cake on your kitchen counter.”
The body produces inflammatory mediators when there’s a trigger—like an infection. This acute inflammation is a protective and repair mechanism. But when the trigger persists, inflammation can become chronic. The paper hypothesized that chronic inflammation may be a driver for cancer. Nowhere did it mention that seed oils caused chronic inflammation.
Too much omega 6 is not ideal, and seed oils can be rich in omega 6. But it’s more about omega 3 : 6 ratio - and not just omega 6 by itself (more on that later).
Dr. Dariush Mozaffarian, MD, DrPH, dean of the Friedman School of Nutrition at Tufts, sums it up perfectly here.
My Take:
Don’t panic. That 1 tablespoon of canola oil in your veggie stir-fry isn’t plotting your demise or giving you colorectal cancer.
Chronic inflammation is the real villain here – and it comes from things like:
Overconsumption of packaged, ultra-processed foods, fast food, and excess refined sugar,
Stress,
Environmental toxins & hidden infections
… and not your home-cooked meals. So stir-fry away, and keep the focus on balance, whole foods, and LOTS OF FIBER if keeping colon cancer at bay is your priority.
I used to think Canola Oil was ‘Inflammatory’ too...
Confession time: I once bought into the idea that canola oil was bad news 🫢. I fell into the trap of accepting claims from “functional medicine doctors” without digging deeper. But when I started thoroughly researching the topic, here’s what I found:
A study of 70 people with Type II diabetes found that consuming 30g of canola oil reduced inflammation markers (CRP) compared to sunflower oil.3
A systemic review showed that canola oil improves cholesterol levels better than sunflower oil, saturated fats, and even olive oil in some cases.4
And no, I don’t work for “Big Canola Oil” 🤣 - and I don’t even use the stuff (I’ll share the oils I DO use below.) - I’m just here to say there is not a whole lot of human data to back the “Canola oil is the demon” rhetoric rife on social media.
One caution I will throw in here is that these plants are often sprayed with pesticides, many of which are lipophilic (i.e., they dissolve in fat) - so IF you do use it, make sure it is organic.
Also, I DO have a problem with ultra-processed foods, and most of them use canola oil (or other seed oils, so context matters - And here’s my unpopular opinion: chips made with coconut oil or tallow don’t magically turn into wellness snacks. They are still chips, not conducive to health, no matter how you slice or dice it. Now that’s not to say I don’t enjoy chips here and there - I DO! It’s all about balance.
When Is Omega-6 Actually ‘Bad’?
Omega-6 becomes a problem when it significantly outweighs omega-3 in your diet. This imbalance usually stems from eating too many ultra-processed foods. If your meals are mostly whole foods made from scratch, a little seed oil here and there won’t hurt.
When I eat out, or have more ultra-processed foods in my diet, I know I’m consuming more omega-6, but I don’t stress. Instead, I enjoy the meal (yup even chips!) and balance it out later with omega-3-rich foods. There’s no need to panic—or be extreme.
