Objective: This study reviews epidemiological works having studied the associations of dietary fatty acids, especially of n-6 or n-3 polyunsaturated fatty acids (PUFA), with the risks of colorectal and prostate cancers.
Methods: The epidemiological studies reviewed were those having tested the association of colorectal and prostate cancer risk with the dietary intake or the blood or adipose tissue levels of fatty acids, especially of n-6 and n-3 PUFA, and with the dietary intake of fish and seafood.
Results: Most studies based on a dietary questionnaire did not find any association of the risk of colorectal cancer with the consumption of either total fatty acids or any particular fatty acid, after adjustment for total energy intake had been made. A few studies suggest that trans fatty acid consumption could increase colorectal cancer risk. Most studies based either on a dietary questionnaire or on biomarkers, did not find any association of total, saturated or monounsaturated fatty acid, as well as of linoleic or arachidonic acids, with prostate cancer risk, after adjustment for total energy intake. Most studies failed to find an association of prostate cancer risk with fish or long-chain n-3 PUFA intake, but recent cohort studies did find an inverse association of fish consumption with the risk of the latest stages of prostate cancer. In contrast, alpha-linolenic acid intake was associated with an increase of prostate cancer risk in a majority of epidemiological studies, but other studies did not find this association. This latter point might be of concern, and needs to be clarified by other results, especially those of ongoing prospective studies.