Letter to the Editor Vitamin D and Cancer Incidence—Response

We thankWeir and Borek (1) for the thorough reading of our article (2). Weir and Borek mention the limita-tions of the use of a single vitamin D measurement despite the potential individual variations in vitamin D status. This is a valid point because a single vitamin D measurement at baseline may lose predictive power over time. However, the estimates were very similar, when we only included a 5-year follow-up period in the three studies (3). In addition, Jorde and colleagues (4), who reported significant individual changes in vitamin D status after 14 years of follow-up, found vitamin D status to be as stable a predictor as lipids and blood pressure. However, we acknowledge that the use of a single vitamin D measurement may not accurately reflect vitamin D exposure in the long term, and thi