Researchers at the National Institute of Environmental Health Sciences (NIEHS) have shown a connection between the consumption of long-chain omega 3 fatty acids and colorectal cancer prevention. But there was one odd and unexpected caveat—the benefit was only observed in white study participants, not African-American participants.

In a presentation at the American Association for Cancer Research’s “Frontiers in Cancer Prevention Research” conference, the researchers, headed by Sangmi Kim, PhD, a visiting fellow at the NIEHS’ Epidemiology Branch in Research Triangle Park, NC, explained how they studied the link between polyunsaturated fatty acid intake and distal large bowel cancer using data from a population-based control study. They recruited 1509 white participants (716 cancer cases and 787 controls) and 369 black participants (213 cancer cases and 156 controls) using the State Cancer Registry and Division of Motor Vehicles records.

Nineteen polyunsaturated fatty acids were assessed using a validated food frequency questionnaire, which included 124 questions on food items. The researchers used the questionnaire to collect information on the frequency and amount of foods typically consumed in the past 12 months.

Patients who consumed more long-chain omega 3 fatty acids had a reduced risk of distal large bowel cancer. Compared to the lowest quartile, fat intake in the highest quartile was linked with a 39% reduced risk of cancer.

Experimental data have shown benefits of long-chain omega 3 fatty acids in colorectal carcinogenesis, ranging from reduced tumor growth, suppression of angiogenesis and inhibition of metastasis,” said Dr.  Kim. “Our finding of inverse association between dietary intakes of long-chain omega 3 fatty acids and distal large bowel cancer in white participants adds additional support to the hypothesis.

While experimental and clinical data suggest that long-chain omega 3 fatty acids possess anti-neoplastic properties in the colon, epidemiologic data to date has been inconclusive.

The Racial Disparity

In an interview with Nutraceuticals World, Dr. Kim said she and her colleagues were surprised to discover that the colon benefits of omega 3 fatty acid consumption were observed in white participants but not African American participants.

We considered several possible explanations that might have contributed to the results but were not able to account for this difference with the data we had,” she said. “Although we did find an unexpected positive association between intake of long-chain omega 3 fatty acids and distal large bowel cancer in African Americans, this finding should be interpreted with caution, waiting for confirmation by both laboratory and other epidemiologic data.”

She also stressed, “We should be careful about drawing conclusions about potential racial differences in benefit from long-chain omega 3 fatty acids from this study.”

Dr. Kim said that examining the relationship between omega 3s and colon cancer dovetailed with her interest in studying the role of inflammation in carcinogenesis. “Chronic inflammation has long been recognized as a part of the carcinogenic process. Moreover, growing evidence suggests that inflammation may be an underlying mechanism by which many of observed cancer risk factors such as older age, obesity and use of nonsteroidal anti-inflammatory drugs, may influence cancer risk,” she said.

In addition to the research presentation at the Frontiers in Cancer Prevention Research conference, Dr. Kim said the manuscript has also been accepted for publication in the American Journal of Epidemiology.

Looking forward, Dr. Kim and her colleagues are continuing their studies of omega 3 but on a different area of focus—breast cancer. The team is currently examining the relationship between omega 3 fatty acid intake and breast cancer risk using data from another study. The results are not yet ready for release.