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Dietary intake of omega-6 and omega-3 fatty acids and risk of colorectal cancer in a prospective cohort of U.S. men and women

Daniel CR, McCullough ML, Patel RC, Jacobs EJ, Flanders WD, Thun MJ, Calle EE

Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology, 2009

99,080 participants

Abstract

BACKGROUND: omega-6 and omega-3 polyunsaturated fatty acids intakes may play opposing roles in inflammation-driven colorectal carcinogenesis. We examined the relationship of these polyunsaturated fatty acids and the ratio of their intake with colorectal cancer risk in a large U.S. prospective cohort.

DESIGN: Participants in the Cancer Prevention Study-II Nutrition Cohort completed a detailed questionnaire on diet, medical history, and lifestyle in 1999. Between 1999 and 2005, 869 incident colorectal cancer cases (452 men and 417 women) were identified among 99,080 participants (43,108 men and 55,972 women). Multivariate-adjusted rate ratios were calculated using Cox proportional hazards models.

RESULTS: The ratio of total omega-6 to total omega-3 intake was not associated with colorectal cancer risk in either sex. Contrary to our initial hypothesis, total omega-6 intake was inversely related to colorectal cancer risk in men [multivariate relative risk (95% confidence interval) for highest to lowest quartile, 0.81 (0.61-1.07); P(trend) = 0.07], and alpha-linolenic acid, the primary contributor to total omega-3 intake, was associated with increased risk in women for quartiles 2 through 4 versus the lowest quartile [relative risk (95% confidence interval), 1.50 (1.12-2.01), 1.40 (1.04-1.87), and 1.38 (1.02-1.85), respectively; P(trend) = 0.13]. In women, total omega-6 and marine omega-3 intake appeared to be associated with higher and lower risk, respectively, but associations…

How strong is the evidence?

Evidence Hub reads this as a cohort study, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 99,080 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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