N-3 Long Chain Fatty Acids Supplementation, Fatty Acids Desaturase Activity, and Colorectal Cancer Risk: A Randomized Controlled Trial

Nutr Cancer. 2022;74(4):1388-1398. doi: 10.1080/01635581.2021.1955286. Epub 2021 Jul 22.


Introduction: n-3 long-chain polyunsaturated fatty acids (LCPUFA) have anti-inflammatory effects and may reduce colorectal cancer risk. The purpose of this study was to evaluate the effects of n-3 LCPUFA supplementation on markers of rectal cell proliferation and apoptosis and examine how genetic variation in desaturase enzymes might modify this effect.

Methods: We conducted a randomized, double-blind, control six-month trial of 2.5 grams of n-3 LCPUFA per day compared to olive oil. Study participants had a history of colorectal adenomas. Randomization was stratified based on the gene variant rs174535 in the fatty acid desaturase 1 enzyme (FADS1). Our primary outcome was change in markers of rectal epithelial proliferation and apoptosis.

Results: A total of 141 subjects were randomized. We found no difference in apoptosis markers between participants randomized to n-3 LCPUFA compared to olive oil (P = 0.41). N-3 LCPUFA supplementation increased cell proliferation in the lower colonic crypt compared to olive oil (P = 0.03) however baseline indexes of proliferation were different between the groups at randomization. We found no evidence that genotype modified the effect.

Conclusions: Our study did not show evidence of a proliferative or pro-apoptotic effect on n-3 LCPUFA supplementation on rectal mucosa regardless of the FADS genotype.ClinicalTrials.gov Identifier: NCT01661764Supplemental data for this article is available online at https://dx.doi.org/10.1080/01635581.2021.1955286.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Colorectal Neoplasms* / genetics
  • Colorectal Neoplasms* / prevention & control
  • Delta-5 Fatty Acid Desaturase
  • Dietary Supplements
  • Fatty Acids
  • Fatty Acids, Omega-3* / pharmacology
  • Humans
  • Olive Oil / pharmacology


  • Delta-5 Fatty Acid Desaturase
  • Fatty Acids
  • Fatty Acids, Omega-3
  • Olive Oil

Associated data

  • ClinicalTrials.gov/NCT01661764