Total calcium intake and colorectal adenoma in young women

Abstract

Background: Total calcium intake appears to reduce occurrence of colorectal adenoma; however, the dose necessary for prevention in young women is unclear. We examined fine categories of calcium intake in relation to occurrence of first colorectal adenoma in a cohort of mostly premenopausal (88 %) women aged 26-60 at time of endoscopy.

Design: We conducted an analysis among 41,403 participants in the Nurses' Health Study II and assessed intakes of calcium prior to endoscopy through participants' responses to biannual questionnaires.

Results: Between 1991 and 2007, we documented 2,273 colorectal adenoma cases. There was a significant trend across categories of calcium intakes with lowest intakes suggestive of higher occurrence of adenoma (p = 0.03) and those in the distal colon (p = 0.03) and rectum (p = 0.04). Compared with 1,001-1,250 mg/day of calcium intake, ≤ 500 mg/day was suggestive of a modest increase in occurrence of adenoma (multivariable RR = 1.21, 95 % CI 0.90-1.61); there were also suggestions of an increased risk with >500 to ≤ 700 mg/day of calcium. The association between ≤ 500 mg/day of calcium intake and adenoma was stronger for multiple (RR = 2.27, 95 % CI 1.38, 3.72), large (≥ 1 cm) (RR = 2.01, 95 % CI 1.27, 3.21), and high-risk adenoma (≥ 1 cm or mention of villous histology/high-grade dysplasia) (RR = 1.76, 95 % CI 1.13, 2.72). No differences in associations were noted between jointly categorized calcium and phosphorus or magnesium intakes.

Conclusions: Our findings suggest that low intakes of calcium, <500 and possibly 500-700 mg/day, in younger women are associated with an increased risk of multiple and advanced colorectal adenoma.