Associations of Calcium, Vitamin D, and Dairy Product Intakes with Colorectal Cancer Risk among Older Women: The Iowa Women's Health Study

• Authors: Caroline Y. Um, Emory University; Anna Prizment, University of Minnesota; Ching-Ping Hong, University of Minnesota; DeAnn Lazovich, University of Minnesota; Roberd Bostick, Emory University
• Journal Title: Nutrition and Cancer: An International Journal
• Volume: Volume 71, Number 5
• Publisher: Taylor & Francis Ltd. | 2019-07-04, Pages 739-748
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1080/01635581.2018.1539188
• Subjects: Health Sciences, Oncology; Health Sciences, Nutrition; Health Sciences, Public Health
• Keywords: Science & Technology; Life Sciences & Biomedicine; Oncology; Nutrition & Dietetics; Growth factor I; Dose response metaanalysis; Normal colon mucosa; Supplemental calcium; Circulating levels; Milk consumption; Catenin pathway; Double blind; Insulin; Recurrence

Abstract

Calcium and, to a lesser extent, dairy products are consistently modestly inversely associated with colorectal cancer (CRC). Dairy products may contain components other than calcium and fat, such as insulin-like growth factor-1, that may affect CRC risk. In the prospective Iowa Women’s Health Study, calcium, dairy product, and vitamin D intakes were assessed using a semiquantitative food frequency questionnaire. To investigate dairy products independent of their calcium components, we estimated residuals from linear regression models of their associations with dietary calcium. Of the 35,221 55–69-year-old cancer-free women at baseline in 1986, 1,731 developed CRC during follow-up through 2012. For those in the highest relative to the lowest intake quintiles, the adjusted hazards ratios and 95% confidence intervals from multivariable Cox proportional hazards regression models for overall and distal CRC were 0.81 (0.67–0.98; P trend = 0.004) and 0.59 (0.44–0.80; P trend = 0.003), respectively, for total calcium; and 0.79 (0.66–0.94; P trend = 0.01) and 0.69 (0.53–0.90; P trend = 0.003) for total dairy products, respectively. The various dairy product residuals were not associated with CRC. These results support that, among women, calcium and dairy products may be inversely associated with CRC—perhaps primarily distal CRC—but suggest that the non-calcium, non-fat component of dairy products may not be associated with CRC.