Selected dietary micronutrients and the risk of right- and left-sided colorectal cancers: a case-control study in Western Australia.
OBJECTIVE
Contradictory results about the role of dietary factors in the causation of colorectal cancer (CRC) may partly be due to failure to discriminate between left- and right-sided CRC.


METHODS
We undertook a population-based case-control study comparing 577 cases of left-sided CRC and 277 cases of right-sided CRC (n = 277) with 958 age- and sex-matched controls. Dietary exposure was measured using a food frequency questionnaire. Odds ratios (OR) were calculated across quintiles of dietary intakes of micronutrients, adjusting for potential confounders.


RESULTS
Compared to those in the lowest quartiles of intake, we found a protective role of phosphorus on CRC particularly for right-sided cancers (Q5 OR = 0.66, 95% confidence interval [CI]: 0.52-1.02) and protective associations for iron and zinc were observed with left-sided cancers (Q5 OR = 0.78, 95% CI: 0.56-1.09 and Q5 OR = 0.65, 95% CI: 0.46-0.92, respectively). An increased risk of left-sided cancer, was observed for vitamin E (Q5 OR = 1.37, 95% CI: 0.97-1.96).


CONCLUSIONS
An increased risk of CRC was observed for vitamin E and decreased risks were seen for phosphorus, iron, and zinc. Differences in the risk of developing CRC according to subsite were observed for phosphorus and vitamin E.
Western Australian Institute for Medical Research, University of Western Australia, Nedlands 6009, Australia.
Linde
L
van Lee
Jane
J
Heyworth
Sarah
S
McNaughton
Barry
B
Iacopetta
Cassandra
C
Clayforth
Lin
L
Fritschi
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D004032:Diet; D004034:Diet Surveys; D005260:Female; D006801:Humans; D019266:Iron, Dietary / Q000008:administration & dosage / Q000009:adverse effects; D008297:Male; D018977:Micronutrients / Q000008:administration & dosage / Q000009:adverse effects*; D008875:Middle Aged; D016017:Odds Ratio; D016226:Phosphorus, Dietary / Q000008:administration & dosage / Q000009:adverse effects; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014810:Vitamin E / Q000008:administration & dosage / Q000009:adverse effects; D014904:Western Australia / Q000453:epidemiology; D015032:Zinc / Q000008:administration & dosage / Q000009:adverse effects
D019266:Iron, Dietary; D018977:Micronutrients; D016226:Phosphorus, Dietary; D014810:Vitamin E; D015032:Zinc