Scientists warn of impact of cooking oils on cancer growth rates

A new study suggests that adjusting the balance of dietary fats may help slow the growth of cancer cells, highlighting the potential role of nutrition in managing early-stage disease.

Omega-6 fats — commonly found in vegetable oils, fried foods and many processed products — are widely consumed in modern diets. Omega-3 fats, abundant in oily fish such as salmon and sardines, are often eaten in much smaller amounts. In some Western diets that contain large parts of processed foods, people consume 15 to 20 times more omega-6 than omega-3, while researchers believe a ratio closer to 4:1 should be aimed for. An excess of omega-6 relative to omega-3 has been linked to increased inflammation, a condition that may support cancer cell growth.

Dr. William Aronson, a urology professor at the UCLA David Geffen School of Medicine, set out to examine whether modifying fat intake could influence the progression of prostate cancer.

“This is an important step toward understanding how diet can potentially influence prostate cancer outcomes,” said Aronson, as cited by the Earth platform.

The study, published in the Journal of Clinical Oncology, enrolled 100 men with early-stage prostate cancer who were undergoing “active surveillance,” a medical approach in which patients with slow-growing tumours delay immediate treatment such as surgery or chemotherapy and instead monitor the disease closely.

Participants were randomly divided into two groups. One group continued their usual diet. The other worked with a dietitian to reduce omega-6 intake, increase omega-3 consumption and take daily fish oil supplements. The program did not require calorie restriction or weight loss.

“Many men are interested in lifestyle changes, including diet, to help manage their cancer and prevent the progression of their disease,” Aronson explained.

To assess changes in tumour activity, researchers measured Ki-67, a marker that indicates how quickly cells are dividing. Higher Ki-67 levels signal faster cell proliferation, while lower levels suggest slower growth.

Each participant underwent a biopsy at the beginning of the study and again one year later. Using MRI guidance, researchers sampled tissue from the same tumour location both times, improving the precision of comparisons — an advance over earlier studies that relied on less targeted sampling.

After one year, the two groups showed different patterns. Ki-67 levels decreased among men who modified their diets but increased in those who maintained their regular eating habits. The findings indicate that cancer cells in the diet-adjustment group were dividing more slowly, while cell division accelerated in the control group.

“Our findings suggest that something as simple as adjusting your diet could potentially slow cancer growth and extend the time before more aggressive interventions are needed.”

However, other clinical measures remained unchanged. Prostate-specific antigen (PSA) levels and tumour grades were similar in both groups.

The researchers also noted that some participants withdrew from the study due to gastrointestinal side effects linked to fish oil supplements, which can interact with blood thinners and other medications.

“This significant difference suggests that the dietary changes may help slow cancer growth, potentially delaying or even preventing the need for more aggressive treatments,” Aronson continued, cautioning that the results do not indicate that dietary changes alone can cure cancer.

By Nazrin Sadigova