|M.Sc Student||Chaiter Yoram|
|Subject||Nutritional Epidemiology of Colorectal Cancer-Carotenoids|
|Department||Department of Medicine||Supervisor||Professor Gad Rennert|
Background: Controversy exists around possible protective role of carotenoids in the causation of colorectal cancer(CRC). No information exists about the role of their isomers.
Objectives : To examine the associations of dietary intake of carotenoid isomers with the risk of developing CRC.
Methods: A population based case- control
study in Northern Israel with matched population controls. A semi quantitative
food frequency questionnaire was used. Carotenoid isomers database was
created by analyzing all food items for carotenoid isomers content using HPLC.
Mean daily intake of carotenoid isomers was calculated. Odds ratios and 95% confidence intervals were calculated from a conditional logistic regression model including energy, fiber, fat , vitamins D, C, E, fruits and vegetable consumption, age ,use of NSAID’S ,family history of CRC and physical activity as covariates.
Results : 712 pairs of
cases and controls were included in analysis.9-cis-
beta-carotene, all-trans beta-carotene, beta- zea-carotene, cis-
beta-cryptoxanthin, zeaxanthin and lutein were inversely associated with CRC
risk . In females, only 9-cis beta-carotene, all-trans beta-carotene and
beta -zea-carotene were protective. In the older age group (>70 yrs) ,only
9- cis beta carotene, all -trans- beta carotene and beta- zea- carotene were
No protective effects of carotenoids were noticed in current smokers.
In Ashkenazi Jews 9-cis beta-carotene, all-trans- beta-carotene and beta- zea-carotene were found protective. Only all-trans- beta-carotene was found to be protective in Sephardi Jews 9-cis -beta-carotene, all-trans- beta-carotene, zeaxanthin and lutein were protective against left side tumors of the colon. 9-cis beta-carotene and beta- zea-carotene were protective against right side tumors. Rectal tumors were protected by 9-cis- beta-carotene, zeaxanthin and lutein .
Lycopene increased the risk of CRC in most subgroups except in Sephardic Jews and current smokers.
The protective effects of carotenoid isomers differed by age, ethnicity and gender. A broader protective effect was noticed for left-sided colon tumors.The finding of lycopene as increasing the risk of CRC is intriguing and deserves further study.