Calcium, Vitamin D And Risk Of Colorectal Cancer In Canadian Populations

Objective Despite evidence from animal studies for a protective effect of higher calcium and possibly vitamin D and dairy product intake against colorectal cancer (CRC),epidemiologic studies have been inconclusive.We therefore examined the association between these factors and risk of colorectal cancer in a large case-control study from Newfoundland(NL) and Ontario(ON).Methods We analyzed data from a population-based case-control study of more than 4,000 participants from Newfoundland and Ontario,Canada.In NL incident cases diagnosed during 1999-2003 were identified through the Newfoundland Familial Colorectal Cancer Registry(NFCCR).In ON incident cases diagnosed during 1997-2000(Phaseâ… ) and 2003-2006(Phaseâ…¡) were identified through the Ontario Familial Colorectal Cancer Registry(OFCCR).Both registries were used to identify newly diagnosed cases of colon or rectal cancer and aged 20-74 years.Controls were a sex and age-group matched random sample of the population of each province. Intakes of calcium and vitamin D from diet and supplements and consumption of dairy products were assessed with a baseline food frequency questionnaire(FFQ). Calcium,vitamin D and dairy products were categorized into quartiles based on the distribution among the study population with lowest quartitle as referent group. Multivariate logistic regression analysis was used to examine the association between these factors and risk of colorectal cancer after adjusting for age,gender,total energy intake,BMI,physical activity,and nonsteroidal anti-inflammatory drug(NSAID) et al.The trends were tested with the medians of the intake as a continuous variable in the logistic model.The P values for the trends were two-sided.Results Total calcium intake(from diet and supplements) was significantly associated with lower risk of colorectal cancer in NL and ON,particularly among women(ORs highest vs lowest quartile were 0.49,95%CI:0.26-0.92,P_trend=0.04 in NL;and OR=0.53,95%CI:0.37-0.76,P_trend=0.02 in ON).Total vitamin D intake(from diet and supplements) was inversely associated with risk of colorectal cancer in NL (OR=0.52,95%CI:0.36-0.74,P_trend=0.04).Dietary Calcium and vitamin D intakes were associated with reduced risk in ON women(OR=0.64,95%CI:0.44-0.93, P_trend=0.03 for dietary calcium;OR=0.68,95%CI:0.49-0.94,P_trend=0.04 for dietary vitamin D),while the use of calciumlcium and vitamin D supplements were associated with lower risk in NL men(OR=0.53 for calcium supplements;OR=0.60 for vitamin D supplements) and NL women(OR=0.46 for calcium supplements; OR=0.46 for vitamin D supplements) and ON men(OR=0.69 for calcium supplements;OR=0.76 for vitamin D supplements).Consumption of high fat dairy products was associated with increased risk of CRC in NL(OR=1.54,95%CI:1.09-2.17),while consumption of non-fat milk and yogurt was associated with reduced risk in ON(OR=0.53 for non-fat milk;and OR=0.60 for yogurt).The inverse association for total calcium intake was strongest in cancer of rectum(OR=0.56,95%CI:0.32-1.00 in NL;OR=0.74,95%CI:0.55-1.00 in ON), while the inverse association for total vitamin D intake was limited to cancer of colon (NL:OR=0.65,95%CI:0.42-0.98).The inverse association for calcium supplements use was strongest among men with lower intake of dietary calcium(OR=0.29 in NL, OR=0.67 in ON).The inverse association was strongest among women with higher intake of total calcium and total vitamin D together(NL:OR=0.49;ON:OR=0.38)Conclusions High calcium and vitamin D intakes,particularly from supplements,are associated with a reduced risk in NL population.High calcium and vitamin D intakes, particularly from food,are associated with a reduced risk of CRC in ON females, while the inverse association was strongest for calcium from supplements in ON males.Consumption of high fat milk may increase risk,while consumption of skim milk or yogurt may decrease risk.The inverse association for total calcium was strongest in rectum cancer,while the inverse association for total vitamin D was limited to colon cancer.Calcium supplements use appears to have further benefits among males with lower intake of dietary calcium.Women with higher intakes of calcium and vitamin D together had the lowest risk of colorectal cancer.In conclusion, calcium and vitamin D intakes were inversely associated with colorectal cancer risk.