High Omega-3, Omega-6 Levels May Lower Cancer Risk

High levels of omega-3 and omega-6 fatty acids—often called “healthy fats”—may help protect against various types of cancer, according to new research published in the International Journal of Cancer.¹

Drawing from data on over 250,000 participants in the UK Biobank study, researchers from the University of Georgia found that people with elevated levels of these fats in their bloodstream had a reduced risk of developing multiple forms of cancer, including colon, stomach, and lung cancer.²

Of the 19 site-specific cancers studied, 14—head and neck, esophagus, stomach, colon, rectum, hepatobiliary tract, pancreas, lung, malignant melanoma, connective soft tissue, kidney, bladder, brain, and thyroid cancer—were inversely associated with omega-6 levels, with a 3% to 7% reduced risk per SD increase in omega-6.¹ Four types of cancers had this relationship with omega-3 levels—colon, stomach, hepatobiliary tract, and lung cancer—with every increase in SD lowering the risk by 5% to 8%.

Omega-3 and omega-6 fatty acids are naturally found in fatty fish, nuts, and some plant oils | Image credit: zilvergolf – stock.adobe.com

However, prostate cancer had a different type of association, with higher omega-3 levels linked to a 3% increased risk of cancer. Meanwhile, 4 types of cancer—ovarian, breast, uterine, and those affecting lymphoid and hematopoietic tissues—had no significant association with either omega-3 or omega-6 levels.

Despite not protecting against 3 cancers mainly affecting women, omega-6 fatty acids seemed to have a stronger overall protective effect among younger individuals, especially women. These findings based on age and sex underscore the complexities of how diet influences cancer risk and suggest that the benefits of omega-3 and omega-6 fatty acids may not be one-size-fits-all.

“For women, it’s an easy decision: Eat more omega-3,” said Kaixiong Ye, PhD, associate professor at the University of Georgia and author of the study.² For men, however, the decision to increase omega-3 intake might require more careful consideration.

Known to support heart and brain health, omega-3 and omega-6 fatty acids are naturally found in fatty fish, nuts, and some plant oils, but most Americans don’t consume enough of these foods. This gap has led to the growing popularity of fish oil supplements, which have been shown in past studies to help lower cholesterol and reduce the risk of heart disease.³

“These findings suggest that the average person should focus on getting more of these fatty acids in their diets,” said Yuchen Zhang, lead author of the study and doctoral student in the University of Georgia’s College of Public Health.²

Despite the positive findings, the study raises questions about the role these fats play in cancer risk. Earlier research into the effects of polyunsaturated fatty acids on cancer had produced mixed results, and while this new study provides robust data, the researchers caution that more investigation is needed to understand these relationships fully.¹

The study had some limitations, including the fact that most participants were of European White ancestry, which means the results may not apply to all racial and ethnic groups. Additionally, as an observational study, it could not fully account for all variables or potential inaccuracies. The sample size was also small for certain cancer types, which may have affected the strength of the findings.

“Our study laid a solid foundation for future mechanistic studies into the roles of PUFAs [polyunsaturated fatty acids] in the etiology of various cancers,” the study authors concluded. “It also provided insights into the development of cancer prevention strategies by man-aging circulating PUFAs.”

References

1. Zhang Y, Sun Y, Song S, et al. Associations of plasma omega-6 and omega-3 fatty acids with overall and 19 site-specific cancers: a population-based cohort study in UK Biobank. Int J Cancer. Published online October 17, 2024. doi:10.1002/ijc.35226
2. High levels of omega-3, omega-6 may protect against cancer. News release. University of Georgia. November 4, 2024. Accessed November 5, 2024 https://www.newswise.com/articles/high-levels-of-omega-3-omega-6-may-protect-against-cancer/?sc=sphr&xy=10050189
3. Hataway L. At risk of high cholesterol? taking fish oil may help. University of Georgia. August 5, 2024. Accessed November 5, 2024. https://news.uga.edu/fish-oil-supplements-fight-risk-of-high-cholesterol/