July 09, 2019
2 min read

Eating fish may decrease colorectal cancer risk

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Eating fatty or lean fish or shellfish as part of a regular diet may help decrease the risk for colorectal cancer, according to study results.

Elom K. Aglago, PhD, of the nutrition and metabolism section at the International Agency for Research on Cancer, and colleagues wrote in Clinical Gastroenterology and Hepatology that fish is a source of long-chain n-3 polyunsaturated fatty acids (n-3 LC-PUFAs), which other studies have shown to have an inverse association with CRC risk.

“The World Cancer Research Fund concluded, based on a meta-analysis of 18 prospective studies, that there was ‘limited but suggestive’ evidence that fish decreases CRC risk,” they wrote. “Nevertheless, there is still uncertainty whether fish consumption is beneficial for CRC prevention and how consumption of different fish types (eg, fatty/oily, white/lean) relates to CRC risk.”

Researchers used data from the European Prospective Investigation into Cancer and Nutrition cohort to explore the association between fish consumption, as well as dietary and circulating levels of n-3 LC-PUFAs, with CRC. They estimated fish consumption using food frequency questionnaires given to 521,324 individuals involved in the cohort. Of those, 6,291 developed CRC with a median follow-up of 14.9 years.

Investigators measured phospholipid LC-PUFA levels using gas chromatography in plasma samples collected from a sub-group of 461 patients with CRC and 461 matched individuals without CRC.

Aglago and colleagues determined that total intake of fish (HR for quintile 5 vs. 1 = 0.88; 95% CI, 0.8–0,96), fatty fish (HR = 0.9; 95% CI, 0.82–0.98) and lean fish (HR = 0.91; 95% CI, 0.83–1) were all inversely associated with CRC incidence. Overall, 100 g to 200 g of fatty or lean fish in a weekly diet was associated with a 7% lower CRC risk.

Additionally, intake of total n-3 LC-PUFA was also associated with reduced risk for CRC (HR = 0.86; 95% CI, 0.78–0.95). Although plasma levels of phospholipid n-3 LC-PUFA was not associated with overall CRC risk, researchers observed an inverse trend for proximal compared with distal colon cancer. They also determined that the dietary ratio of n-6 to n-3 LC=PUFAs was associated with increased risk for CRC (HR = 1.31; 95% CI, 1.18–1.45).

Aglago and colleagues wrote that their findings provide additional evidence that eating more fish could help lower risk for CRC.

“The biological mechanisms through which fish consumption potentially lowers CRC risk are not fully understood,” they wrote. “Fatty/oily fish are primary sources of n-3 LC-PUFAs which may inhibit cancer development through the production of eicosanoids that possess anti-inflammatory properties. Although fat content is lower in lean/white fish compared to fatty fish, lean fish could be a non-negligible source of n-3 LC-PUFAs.” by Alex Young

Disclosures: The authors report no relevant financial disclosures.