Effect of dietary fish oil on fecal bile acid and neutral sterol excretion in healthy volunteers.

Diet-induced increases in fecal excretion of secondary bile acids (deoxy- and lithocholic acid) and certain neutral sterols (4-cholesten-3-one and 5a-cholestan-3-one) play a role in colon cancer development, whereas dietary fish oil (FO) has been implicated as a protective agent. In the present study the effects of FO and corn oil (CO) on these fecal parameters were investigated in 12 healthy volunteers consuming a low fat (30% of energy) controlled basal diet. After 4 weeks of FO supplementation (4.4 g omega-3 fatty acids/day), daily excretion of lithocholic acid showed a trend to lower values compared to CO consumption (p = 0.2), whereas other bile acids were not different during both study periods. Daily excretion of the putative colon carcinogen 4-cholesten-3-one was significantly lower in the FO compared to the CO period. This may be another biochemical mechanism by which FO exerts its protective effect on colon cancer development.