Submitted to: Journal of Nutritional Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2007
Publication Date: 4/1/2008
Citation: Jain, D., Ebine, N., Jia, X., Kassis, A., Marinangeli, C., Fortin, M., Beech, R., Hicks, K.B., Moreau, R.A., Kubow, S., Jones, P.J. 2008. Corn fiber oil and sitostanol decrease cholesterol absorption independently of intestinal sterol transporters in hamsters. Journal of Nutritional Biochemistry 19:229-236. Interpretive Summary: Many clinical research studies have demonstrated that eating 1-2 grams per day of plant sterols (phytosterols) will lower the levels of cholesterol in human blood by 10-15%. Since the year 2000, several margarines and other cholesterol-lowering functional foods that are fortified with plant sterols have been marketed in the US. Previous studies from our lab and others have demonstrated that corn fiber oil contains the highest levels of plant sterols (~10%) of any natural oil. The plant sterols occur in three different forms. Two of the forms of plant sterols in Corn Fiber Oil are the common types found in fruits and vegetables and enriched in functional foods. The third type of plant sterol in Corn Fiber Oil, ferulate phytosterol esters, is unique to corn and other cereals. The current report is the first one to demonstrate that ferulate phytosterol esters lower cholesterol in hamsters. The current study is important because it establishes that all of the plant sterols in Corn Fiber Oil contribute to its cholesterol-lowering properties. Also, in addition to the cholesterol-lowering properties of ferulate phytosterol esters, these molecules may have additional health-promoting properties because previous studies by ourselves and others have demonstrated their antioxidant properties.
Technical Abstract: The aim of this study was to investigate the cholesterol-lowering mechanism of corn fiber oil (CFO), ferulate phytostanyl esters (FPE) and parent compounds including sitostanol and ferulic acid in hamsters. Method: Seventy male golden syrian hamsters were randomly assigned to six experimental diets for 4 weeks. 1) Control diet without cholesterol 2) Control diet plus 0.1% (w/w) cholesterol. The remaining four groups were given 0.1 % cholesterol diet with: 3) 10% (w/w) CFO 4) 0.5% (w/w) sitostanol, 5) 0.23% (w/w) ferulic acid and 6) 0.73% (w/w) FPE. At the end of dietary intervention total plasma cholesterol, HDL cholesterol (HDL-C) and triglyceride (TG) concentrations were determined. Parameters of cholesterol kinetics including cholesterol absorption and synthesis as well as mRNA expression of sterol transporters such as Niemann-Pick C1 like 1 (NPC1L1), ATP-binding cassette G5 (ABCG5) and ABCG8 were assessed. Results: Supplementation with CFO decreased (p< 0.0001) plasma total cholesterol levels by 29% as compared with the cholesterol-control group, while FPE and sitostanol reduced cholesterolemia by 15% (p< 0.02) and 14%(p< 0.02), respectively. CFO (p<0.05) and sitostanol (p<0.05) decreased cholesterol absorption by 24% compared to cholesterol-control group. Dietary intervention did not alter intestinal expression of ABCG5, ABCG8 and NPC1L1. Conclusion: The present results show that the CFO and sitostanol-induced decrease in cholesterol absorption is independent of intestinal enterocyte sterol transporters such as ABCG5, ABCG8 and NPC1L1 in hamsters.