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Author: Justin Stebbing, Professor of Biomedical Sciences, Anglia Ruskin University
Original article: https://theconversation.com/fat-in-common-cooking-oils-is-linked-to-aggressive-breast-cancer-but-heres-why-you-shouldnt-panic-254255
There’s now lots of evidence which shows that our own diets and the foods we eat can influence the outcome if we are unlucky enough to suffer from cancer.
Scientists are especially interested in how this happens, in particular the cellular and molecular mechanisms behind these associations. This would better inform nutritional recommendations and help us understand how cancer forms so we can prevent it.
Now, a study has identified a molecular link between linoleic acid, a common fat contained in cooking oils, and aggressive breast cancer, renewing the discussion about dietary choices and cancer risk. The findings, while significant, require careful interpretation to avoid unnecessary alarm and give useful guidance to the public.
Common fatty acid
Linoleic acid is an omega-6 fatty acid which is found in abundant quantities in soybean, sunflower and corn oils. Researchers at Weill Cornell Medicine in New York showed it can directly activate a growth pathway in triple-negative breast cancer cells – a type of breast cancer especially known for its aggressiveness and limited treatment options.
Triple negative breast cancer makes up about 15% of all breast cancer cases, but because breast cancer is so common, this affects a lot of people. The researchers found that linoleic acid binds to a protein called FABP5 (fatty acid-binding protein 5), which is at high levels in these cancer cells.
This binding triggers the mTORC1 pathway – a critical regulator of cell growth and metabolism – fuelling tumour progression in preclinical research, including animal studies. My current research focuses on this pathway in a variety of normal and cancer cells.
In the new study, mice fed a high linoleic-acid diet developed larger tumours, suggesting dietary intake may exacerbate this cancer’s growth. There was a link to people too: elevated FABP5 and linoleic acid levels were detected in blood samples from triple-negative breast cancer patients, strengthening the biological plausibility of this link. Dr John Blenis, the senior author of the paper, said:
This discovery helps clarify the relationship between dietary fats and cancer, and sheds light on how to define which patients might benefit the most from specific nutritional recommendations in a personalised manner.
It’s also possible that the implications extend beyond triple negative breast cancer to other tumours such as prostate cancer.
Linoleic acid is an essential fatty acid so it must be obtained from food. It plays a role in skin health, cell membrane structure and inflammation regulation. However, modern diets, which are rich in processed foods, ultraprocesed foods and seed oils, often provide excessive omega-6 fats, including linoleic acid, while lacking omega-3s, which are found in fish, flaxseeds and walnuts.
This imbalance could promote chronic inflammation, which is a well known contributor to cancer and other diseases.
The study therefore suggests that linoleic acid may directly drive cancer growth in specific contexts. This challenges earlier observational studies that found no clear association between dietary linoleic acid and overall breast cancer risk. For example, a 2023 meta-analysis of 14 studies in over 350,000 women concluded that linoleic acid intake had no significant effect on breast cancer risk in the general population.
The discrepancy highlights the importance of researchers looking specifically at cancer subtypes and also individual factors, such as FABP5 levels in cancers themselves. Another study showed that linoleic acid was protective against breast cancer, which demonstrates why it’s important to consider everything in context.
Don’t panic
Media headlines can often oversimplify complex research. While this new study highlights a plausible mechanism linking linoleic acid to cancer growth, it does not prove that cooking oils cause breast cancer – far from it. Other factors, such as genetics, overall diet and environmental exposures, play significant roles.
The findings do not warrant blanket avoidance of seed oils but suggest moderation and selectivity, especially for high-risk individuals. Many oils such as olive oil contain less linoleic acid and higher monounsaturated or saturated fats, which are more stable at high heat.
Do also consider eating more fruits and vegetables as part of a healthy, balanced diet.
A recent study that comprehensively analysed eating habits over 30 years showed that diets that are rich in fruits, vegetables, whole grains, nuts and low-fat dairy products were linked to healthy ageing. In that study, the Harvard team followed more than 100,000 people between 1986 and 2016. Fewer than 10% of respondents achieved healthy ageing, defined by a lack of 11 major chronic diseases and no impairment in cognitive, physical or mental function by the age of 70.
Organisations like the World Cancer Research Fund emphasise that moderate use of vegetable oils is safe and that obesity, not specific fats, is the primary dietary driver of cancer risk.
This study, then, underscores the importance of contextualising dietary fats in cancer research. While linoleic acid’s role in triple-negative breast cancer is a critical discovery, it’s one piece of a vast puzzle. A balanced, wholefood diet remains an important cornerstone of cancer prevention, and a strategy everyone can adopt.
Justin Stebbing does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
