Abstract:
Objective To evaluate the association between nutrient supplement intake and the risk of colorectal cancer.
Methods A case-control design was employed using information retrieved from the Ontario Familial Colorectal Cancer Registry (OFCCR) from 1 July 1997 to 31 June 2000. We selected cases (n=1 199) who were alive at diagnosis with colon or rectal cancer at the age of 29-80, and recruited controls (n=1 203) in randomly selected households in Ontario. Meanwhile, we collected the in formation of demographic characteristics and nutrient supplement intakes in the cases and controls. Odds ratios (ORs) and 95% confidence intervals (95%CI) of selected supplement intake versus the risk of colorectal cancer were calculated by single factor and multifactor logistic regression.
Results The intakes of vitamin C (OR=0.77, 95%CI:0.64-0.94), vitamin E (OR=0.78, 95%CI:0.64-0.95), and calcium supplements (OR=0.78, 95%CI:0.62-0.98) were protective factors of colorectal cancer. Daily intakes of at least 1 pill of vitamin C (OR=0.76, Ptrend=0.004), vitamin E (OR=0.54-0.79, Ptrend=0.007), and calcium supplements (OR=0.64, Ptrend=0.005), and continuous in takes for at least 5 years of vitamin C (OR=0.61, Ptrend=0.001), vitamin E (OR=0.68, Ptrend=0.005), and calcium supplements (OR=0.69, Ptrend=0.014) reduced the risk of colorectal cancer. After controlling for nutrient supplement interactions, the results of stepwise logistic regression showed that intake of vitamin C (OR=0.75, 95%CI:0.61-0.91) reduced the risk of colorectal cancer.
Conclusion The study findings suggest that intakes of at least 1 pill vitamin C, vitamin E, and calcium supplements for ≥ 5 years continuously could reduce colorectal cancer risk.
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