Eating both omega-3 and omega-6 fats — acids often found in plant foods and fatty fish — may affect cancer risk, according to an October study published in International Journal of Cancer.

    The study found that the more omega-3 and omega-6 fats circulating in the study participants’ blood, the lower their overall likelihood of developing cancer. The association held for 14 different types of cancer, including colon, stomach, lung, brain, bladder and others.

    According to the author of the study Kaikiong “Calvin” Ie, PhDfrom the University of Georgia’s Department of Genetics, these findings confirm what previous studies have suggested. “There have been previous reports of potential benefits of omega-3 and omega-6 fatty acids in reducing cancer incidence and mortality,” he said.

    However, he noted that the new research attempted to avoid some of the limitations of earlier studies, such as relying on self-reported data, using small samples and limiting the number of cancer types examined.

    Here’s a look at what the new research specifically found, as well as what the study means for diet and cancer risk.

    Omega-3 and omega-6 fats are polyunsaturated fats, meaning they have more than one carbon double bond in their chemical chain. In omega-3, this bond is located three carbons away from the end of the chain, while in omega-6, it is six carbons away from the end.

    While these two fats share many similarities in their chemical structure and biological pathways, they affect health in some unique ways. “Omega-3 fatty acids are known to be more involved in brain development, cognitive function and cardiovascular health,” Ye said. “Omega-6 fatty acids are more involved in immune function and skin health.”

    Since the body does not produce omega-3 and omega-6 fats naturally, you can only get them from food. Some of the best sources of omega-3 are fatty fish, while vegetable oils, nuts and seeds are rich in omega-6.

    Many studies have focused on the effects of omega-3s on cancer prevention, but not as many have looked at the effects of omega-6s. The latest study looked at both.

    For their analysis, researchers looked at cancer incidence and blood levels of omega-3 and omega-6 fats in over 250,000 people enrolled in the UK Biobank, a large biomedical database that has been in existence since 2006.

    With an average follow-up period of 12.9 years, the researchers found that, of the 250,000 reported participants, about 30,000 developed any of 19 “specific” cancers (those that occur in specific parts of the body, such as the colon, lung, breast or pancreas). They then compared blood samples from these participants with blood samples from people without cancer.

    After crunching the numbers, they found that higher levels of omega-3 and omega-6 in the blood were associated with a lower risk of multiple cancers. Specifically, elevated levels of omega-3 were associated with a reduced risk of colon, stomach, and lung cancer, while higher levels of omega-6 were associated with lower chances of brain, bladder, kidney, thyroid, and other body cancers. .

    However, some results varied by age. “For overall cancer, the protective associations of omega-3 are stronger in the younger age group and in women,” Ie noted. “On the other hand, the protective associations of omega-6 with overall cancer are stronger in the older age group, in men, and in current smokers.”

    Other differences emerged between the sexes. Three of the four types of cancer that were unrelated to omega-3 or omega-6 levels were those affecting women – breast, ovarian and uterine cancer. There was another significant gender-specific difference: prostate cancer. For unknown reasons, men with higher omega-3 levels had a higher risk of developing this form of cancer.

    The study also found that a higher ratio of omega-6 to omega-3 was associated with an increased overall risk of cancer, with the strongest link between the two involved in rectal, colon and lung cancer.

    While omega-3 fatty acids have gotten a lot of good press over the years, omega-6s don’t have the same glowing reputation. In fact, some social media accounts are buzzing with anti-omega-6 messages, saying these fats are inflammatory or promote heart disease. However, public health authorities like the American Heart Association state that omega-6s are good for the heart and even necessary in adequate amounts.

    What seems to be key – for cancer and other health conditions – is the ratio of omega-3 to omega-6. “The study shows that while higher levels of both omega-6 and omega-3 in the blood are associated with a lower risk of cancer, (a higher) ratio of omega-6 to omega-3 actually increases the risk of cancer.” Taylor Janulevicz, RDNfounder of My Cancer Dietitian, said Health. “This suggests that the balance between omega-6 and omega-3 may be more important than we thought.” Some research suggests that a 1:1 to 2:1 omega-6 to omega-3 ratio may be optimal for disease prevention.

    If you want to add more polyunsaturated fats to your diet, omega-6-rich options include:

    And for more omega-3s, the following foods are good sources:

    To increase your intake, Janulevicz recommends starting with food, not supplements. “Foods offer a variety of additional nutrients that support overall health,” she said. “Whole foods help the body absorb these nutrients more efficiently, while supplements may not offer the same benefits or bioavailability.”