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Effect of polyunsaturated fatty acids on cancer risk
Last reviewed: 02.07.2025
Recent findings published in the International Journal of Cancer shed light on the complex relationship between polyunsaturated fatty acids (PUFAs) and cancer risk.
The Importance of Polyunsaturated Fatty Acids
It is believed that a diet rich in PUFAs may reduce the risk of cancer and improve survival in cancer patients. Potential protective mechanisms of PUFAs include their role in lipid pathways that produce both pro-inflammatory and anti-inflammatory mediators. In addition, PUFAs can alter the composition of cell membranes, affecting cell signaling pathways.
However, definitive evidence for these effects is limited. The study used UK Biobank data, which contains information on more than 500,000 people, to examine the association between omega-3 and omega-6 PUFA levels and cancer risk.
Research Methodology
The researchers analysed data from 29,838 UK Biobank participants diagnosed with cancer who were followed for an average of 12.9 years. Participants were 56.4 years old on average and almost 91% were white. Higher PUFA levels were seen in women, people with a low body mass index (BMI), those who were physically active and those who smoked less.
Research results
Cancer risk decreased with increasing levels of both omega-3% and omega-6%. Specifically, for each standard deviation (SD), cancer risk decreased by 2% for omega-3% and by 1% for omega-6%.
Of the 19 cancer types analyzed, omega-6% was inversely associated with 12 cancer types, and omega-3% was inversely associated with five. Both types of PUFA showed inverse associations for stomach, colon, hepatobiliary, and lung cancers.
Omega-6/omega-3 ratio and cancer risk
Increasing the omega-6/omega-3 ratio was associated with an increased overall cancer risk, as well as an increased risk for three specific cancer types. For example, the risk of colorectal cancer increased by 2% for each standard deviation in the ratio, even after adjusting for factors such as BMI, smoking, alcohol consumption, and physical activity.
Conclusion
The study found small inverse associations of plasma omega-6 and omega-3 PUFA levels with cancer risk. The results also showed an increased risk of prostate cancer with omega-3 PUFA, although this requires confirmation in other studies. If confirmed, the results may support the need for dietary interventions to prevent cancer.