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Vitamin D supplementation in advanced stage colorectal cancer

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By Dr. Julie Ennis, PhD., OICC Research Fellow

Observational research suggest that there is a link between low vitamin D status (based on blood levels of 25(OH)D) and the risk of developing cancer (1) and poorer outcomes in those living with cancer (2). It is not yet certain whether supplementation to achieve optimal blood levels improves outcomes.

The Ottawa Integrative Cancer Centre is currently involved in a randomized controlled trial to explore the safety, tolerability and treatment effects of high-dose vitamin D supplementation for people living with stage IV colorectal cancer. Study participants are randomized to either a control group or a treatment group where vitamin D supplementation is individualized in order to have each study participant attain the high-normal range of serum vitamin D. 

This research study is led by Dr. Hal Gunn, MD of InspireHealth in Vancouver, BC and the OICC is a subsite for this trial led by site PI, Dr. Dugald Seely, ND. To learn more about the study and how to get involved, please contact Julie Ennis, PhD at   


1. McDonnell SL, Baggerly C, French CB, et al. Serum 25-Hydroxyvitamin D Concentrations ≥40 ng/ml Are Associated with >65% Lower Cancer Risk: Pooled Analysis of Randomized Trial and Prospective Cohort Study. PLoS One. 2016;11(4):e0152441. doi:10.1371/journal.pone.0152441.

2.Tretli S, Schwartz GG, Torjesen PA, Robsahm TE. Serum levels of 25-hydroxyvitamin D and survival in Norwegian patients with cancer of breast, colon, lung, and lymphoma: a population-based study. Cancer Causes Control. 2012;23(2):363-370. doi:10.1007/s10552-011-9885-6.

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