BENGALURU: A type of fat commonly found in cooking oils and animal products may be fuelling the growth of one of the deadliest forms of breast cancer, a new research from Weill Cornell Medicine suggests. The study found that linoleic acid — an omega-6 fatty acid abundant in seed oils like soybean and safflower, as well as in pork and eggs — could promote the development and spread of triple-negative breast cancer, a subtype known for its aggressive nature and lower survival rate (77%) compared to other forms of breast cancer (90%).
Published on March 14 in the journal Science, the preclinical study showed that linoleic acid triggers a major growth pathway in tumour cells by binding to a protein called FABP5, which is present in higher amounts in triple-negative cancer cells than in hormone-sensitive ones. In experiments conducted on mice, a diet high in linoleic acid significantly accelerated tumour growth, highlighting the potential for new diet-based and pharmaceutical strategies to combat breast and other types of cancers.
Although the study highlights an alarming trend, health experts stress that fats are essential for the body, and the type and balance of fats consumed can be a factor in maintaining good health.
Fats serve several important functions in the body, such as providing energy, supporting cell structure, and helping with the absorption of certain vitamins. However, not all fats are created equal. There are different types of fats, and they can have vastly different effects on our health, said Dr Sai Vivek V, consultant, medical and haemato oncology at Aster Hospital.
Essential fatty acids
There are two main categories of fats - saturated fats and unsaturated fats. “Unsaturated fats are further divided into monounsaturated and polyunsaturated fats, the latter of which includes omega-6 fatty acids like linoleic acid. While polyunsaturated fats are important for health, the balance between omega-6 and omega-3 fatty acids in our diet is critical,” he said, adding that omega-6 fatty acids, which are abundant in seed and vegetable oils, are essential in small amounts, but consuming too much can lead to negative health outcomes.
Linoleic acid is a type of omega-6 fatty acid found in high amounts in oils such as soybean, corn, sunflower, and safflower oils, Dr Vivek added. “When linoleic acid is consumed in large quantities, the body converts it into arachidonic acid, another omega-6 fatty acid. Arachidonic acid plays a key role in the production of eicosanoids — molecules that regulate inflammation and immune function. While eicosanoids are necessary for certain bodily functions, an excess of them can lead to chronic inflammation. Inflammation, in turn, has been linked to a variety of health issues, including cardiovascular disease, arthritis, and even cancer,” he said.
When it comes to seed oils high in linoleic acid, women, especially with a family history and predisposed to increased risk of cancer, need to be cautious. These seed oils need not be completely eliminated from diet. The key is moderation, says Dr Vivek, explaining that although these oils do not pose any direct harm, when paired with a processed food diet, excessive use can cause inflammation risks which are chronic and known to pose the risk of developing numerous types of cancers including breast cancer.
Instead of complete elimination of these oils, women at risk of cancer need to focus on improving the overall fat balance in their diet and reduce processed food consumption, he added.
Keeping the balance
The shift to seed oil from traditional fats like ghee may have a deleterious impact on gut health and contribute to systemic inflammation, both of which are increasingly associated with chronic diseases such as hormone-sensitive malignancies, as it may upset the balance of omega-6 and omega-3 fatty acids, said Dr Bhuvan Shetty, consultant, medical gastroenterologist and hepatologist at Gleneagles BGS Hospital.
“Trillions of bacteria live in the human gut, helping to regulate immunity, inflammation, and even hormone metabolism. This delicate balance is upset when omega-6 intake surpasses omega-3 intake, which is prevalent in modern Indian cuisine. This promotes the proliferation of pro-inflammatory gut bacteria and reduces microbial diversity,” Dr Shetty said, stressing that this imbalance in gut bacteria can lead to leaky gut syndrome, a condition in which toxins enter the bloodstream and affect hormones.
For women, particularly those with a family history of breast or ovarian cancer, such inflammation may disrupt estrogen metabolism, contribute to hormonal swings, and raise long-term health concerns. “While we do not need to avoid all seed oils, moderation is essential. Balancing them with healthier fats — such as mustard oil and ghee in small amounts alongside nuts and omega-3-rich foods like flaxseed, salmon, and walnuts — can aid in the restoration of hormonal and intestinal equilibrium. A fibre-rich, diverse diet based on traditional eating patterns may be one of our best defence against metabolic and hormone-related diseases,” Dr Shetty added.
An imbalance in fat intake — especially an excess of omega-6 fatty acids relative to omega-3s — can lead to harmful effects, said Bharathi Kumar, dietician, at Fortis Hospital. “The typical Western diet, which relies heavily on oils such as soybean, corn, sunflower, and safflower, contributes significantly to this imbalance.
These oils, though commonly used in everyday cooking, are rich in polyunsaturated fats, which, when consumed excessively, can trigger inflammation,” Bharathi said, explaining that chronic inflammation is linked to a host of diseases, including heart disease, metabolic disorders, and even autoimmune conditions.
Damage to arteries
The body’s prolonged inflammatory response can also strain the cardiovascular system, contribute to arterial damage, and increase the likelihood of developing conditions like atherosclerosis. Furthermore, the consumption of these oils can impact the balance of hormones and gut health, adding to the risk of chronic conditions, she added.
In addition to their role in promoting inflammation, overuse of cooking oils rich in omega-6 fatty acids can also affect the body’s ability to fight disease and regulate its immune responses, Bharathi said, adding that when the body has too much omega-6, it may struggle to absorb enough omega-3 fatty acids, which have anti-inflammatory properties. This creates a dangerous imbalance that can further worsen the body’s inflammatory state and contribute to disease progression.
Oils are essential
Omega-6 fatty acids are a type of polyunsaturated fat essential for brain function, skin and hair growth, and regulating metabolism
Since the body can’t produce them, they must be obtained through diet
Common sources include sunflower oil, soybean oil, sesame oil, rice bran oil, nuts, and seeds
While they are important, excessive intake — especially without enough omega-3s — can lead to inflammation
A balanced omega-6 to omega-3 ratio (ideally around 4:1) is recommended for overall health
Oils rich in linoleic acid
Mustard oil, groundnut oil, sunflower oil, soybean oil, coconut oil, sesame (gingelly) oil, rice bran oil, palm oil, vanaspati, ghee