title: A prospective study of intakes of zinc and heme iron and colorectal cancer risk in men and women.
abstract: Although laboratory studies linked zinc and heme iron to colorectal cancer, epidemiologic evidence is limited. We prospectively examined these associations in the Nurses' Health Study and Health Professionals Follow-up Study. We used Cox proportional hazards regression analyses to calculate cohort-specific relative risks (RRs) and pooled results using a fixed-effects model. We documented 2,114 incident colorectal cancer cases during up to 22 years of follow-up. Compared highest to lowest quintile of dietary zinc intake, the pooled multivariable RRs (95% CIs) were 0.86 (0.73, 1.02) for colorectal cancer, 0.92 (0.76, 1.11) for colon cancer, and 0.68 (0.47, 0.99) for rectal cancer. The significant inverse association between dietary zinc intake and risk of rectal cancer was mainly driven by data in women, although the difference in the sex-specific results was not statistically significant. For the same comparison, the pooled multivariable RRs (95% CIs) for heme iron were 1.10 (0.93, 1.30) for colorectal cancer, 1.06 (0.88, 1.29) for colon cancer, and 1.20 (0.83, 1.75) for rectal cancer. These associations were not significantly modified by alcohol consumption, body mass index, physical activity, menopausal status, or postmenopausal hormone use. Total zinc intake, total iron intake, dietary iron intake, and zinc or iron supplement uses were largely not associated with colorectal cancer risk. Our study does not support strong roles of zinc and heme iron intake in colorectal cancer risk; however, a suggestive inverse association of dietary zinc intake with rectal cancer risk in women requires further study.
authors: Channing Laboratory at Landmark Center (West Wing), Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, 401 Park Drive, Boston, MA 02115, USA. xuehong.zhang@channing.harvard.edu
authors: Xuehong
authors: X
authors: Zhang
authors: Edward L
authors: EL
authors: Giovannucci
authors: Stephanie A
authors: SA
authors: Smith-Warner
authors: Kana
authors: K
authors: Wu
authors: Charles S
authors: CS
authors: Fuchs
authors: Michael
authors: M
authors: Pollak
authors: Walter C
authors: WC
authors: Willett
authors: Jing
authors: J
authors: Ma
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D004032:Diet; D005260:Female; D005293:Ferritins / Q000009:adverse effects*; D006420:Hemeproteins / Q000009:adverse effects*; D049669:History, 16th Century; D006801:Humans; D019266:Iron, Dietary / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D015032:Zinc / Q000009:adverse effects*
chemical_list: D006420:Hemeproteins; D019266:Iron, Dietary; C073694:haemoferritin; D005293:Ferritins; D015032:Zinc