Blood Omega-3 and Omega-6 Levels Linked to Slightly Lower Cancer Risk in Large UK Study

This study used data from over 253,000 adults in the UK Biobank to look at how blood levels of omega-3 and omega-6 fatty acids relate to the chance of developing cancer over an average of nearly 13 years of follow-up. Researchers measured these fats directly in blood plasma rather than relying on diet questionnaires, giving a more objective picture of each person’s fatty acid status.

Overall, both higher omega-6 and higher omega-3 blood percentages were linked to a small reduction in overall cancer risk. When looking at 19 individual cancer types, omega-6 levels were linked to lower risk for 14 of them, and omega-3 levels were linked to lower risk for 5 of them. The one notable exception was prostate cancer, where higher omega-3 levels were associated with a slightly higher risk rather than a lower one.

The associations found were generally modest in size, and this type of study can show patterns and links but cannot prove that omega-3 or omega-6 fats directly cause changes in cancer risk. The researchers accounted for many other factors like age, smoking, alcohol use, BMI, and physical activity, but as with all observational research, other unmeasured factors could still play a role.