Abstract The colorectal cancer (CRC) incidence in Norway has increased considerably during the last fifty years. The main aim of this study was to examine whether hydrogenated fish oil can induce or increase CRC in AOM treated A/J mice.
The effects of three diets containing hydrogenated fish oil (HFO) (19 w/w %); partially hydrogenated (PHFO), highly hydrogenated (HHFO), or totally hydrogenated (THFO), mixed with corn oil (1 w/w %) in AIN-76M, was studied. Fish oil (FO), butter oil (BO), soybean oil (SO), and soybean oil similarly hydrogenated as the fish oil; PHSO, HHSO and THSO were controls.
Tumors identified by surface examination of unsectioned methylene blue stained colon preparations transilluminated in the inverse light microscope, revealed no statistically significant evidence of increasing induction and/or growth of CRC by HFO compared with unhydrogenated FO, or with increasing hydrogenation degree of HFO or HSO, or by HFO in comparison with corresponding hydrogenation degrees of HSO.
On the contrary, PHSO clearly increased tumor growth in females and tumor load in males, compared with PHFO. In females; THFO increased tumor growth compared with PHFO, and PHSO increased tumor number compared with HHSO. In males; THFO increased tumor number compared with PHFO and HHFO, and tumor load compared with HHFO.
Compared with SO; THFO protected females regarding tumor incidence, PHFO regarding tumor growth even though unhydrogenated FO did not seem to protect, and PHFO and HHFO regarding tumor load. Compared with BO; HHFO protected males regarding tumor load even though unhydrogenated FO did not seem to protect.
Patterns in the material seemed to indicate that any of the oils, dependent of gender, showed signs of being related to induction and/or growth of CRC in these animals.