Cooking oils are a staple in kitchens worldwide, from the classic olive oil to the more affordable canola oil. But the health implications of these oils often spark debate, particularly regarding potential links to cancer. While healthy oils like avocado and olive oil boast heart-healthy benefits and may even reduce cancer risk, seed oils like canola, corn, and sunflower are frequently tagged as unhealthy, despite leading health organizations maintaining that they can be part of a balanced diet.
A recent study reignited fears surrounding cooking oils and cancer, prompting concerns about high seed oil consumption— especially from ultra-processed foods. But importantly, the lead author, Dr. Timothy Yeatman, emphasizes that the research doesn’t conclusively prove that any cooking oil causes cancer.
Why are seed oils under scrutiny?
The focus on seed oils stems from their high omega-6 fatty acid content. While omega-6s are essential for bodily functions, excessive intake, compared to omega-3s, can promote inflammation in the body. Numerous studies have linked chronic inflammation to an increased risk of cancer, particularly colon cancer.
Therefore, achieving a balanced ratio of omega-6 to omega-3 fatty acids is crucial for optimal health. According to Mount Sinai, general nutrition guidelines recommend a ratio between 2:1 and 4:1.
Fortunately, omega-6s are also found in beneficial foods like nuts, and omega-3s are plentiful in fatty fish, some seeds, and nuts.
What does the new study reveal?
A recent study by Dr. Yeatman’s team, funded by the National Cancer Institute, investigated the role of lipids (fats) in the tumor microenvironment. Examining 81 colon cancer tumors, they discovered a predominance of pro-inflammatory lipid mediators, primarily omega-6 fatty acids. Conversely, they found scarce amounts of pro-resolving lipid mediators, like omega-3s.
This finding suggests a link between high omega-6 intake and an immunosuppressed environment around cancer cells, potentially allowing tumors to grow and spread.
Should you avoid seed oils?
Dr. Yeatman strongly advises against abandoning all cooking oils, including seed oils, based on this study. Olive oil, for instance, is celebrated for its health benefits and central role in the Mediterranean diet, consistently linked to longevity and preventing chronic diseases. Avocado oil also receives high praise for its heart and eye health benefits.
While seed oils warrant a more cautious approach, Dr. Yeatman highlights that moderate consumption is still deemed healthy. The concern lies in excessive intake and the overconsumption of processed foods rich in seed oils, leading to an unhealthy omega-6 to omega-3 ratio.
“I’m not demonizing seed oil,” he underscores. “But when you eat it at breakfast, at lunch, and in your salad dressing at dinner, it adds up, and that’s the problem.”
The real culprit: ultra-processed foods
All three experts agree that the study ultimately emphasizes the importance of reducing ultra-processed food consumption, where seed oils are often prevalent. This coincides with a concerning rise in colon cancer among young adults, mirroring the dramatic increase in processed food intake.
“We need to … understand that things with a thousand ingredients aren’t very good for you,” Dr. Yeatman warns. “If people want advice, they should start reading labels.”
Dr. Nate Wood, director of culinary medicine at Yale School of Medicine, emphasizes that he’s not concerned about cooking with seed oils. “I’m concerned about the ultra-processed foods that the seed oils are found in… We need to continue driving (that) in because folks are not ready to hear it. They just want to blame the seed oils.”
Prioritize whole foods and balance your fats.
While research on omega-6s and their relationship to colon cancer remains complex, the message for prioritizing a healthy lifestyle remains clear. Embrace whole foods, reduce ultra-processed food intake, and strive for a balanced omega-6 to omega-3 ratio. Your body will thank you.