Calcium supplements and cancer risk: a meta-analysis of randomised controlled trials

Br J Nutr. 2013 Oct;110(8):1384-93. doi: 10.1017/S0007114513001050. Epub 2013 Apr 19.


Some evidence suggests that Ca and vitamin D supplements affect cancer risk; however, it is uncertain whether the effects are due to Ca, vitamin D or the combination. We investigated the effect of Ca supplements without co-administered vitamin D on cancer risk. Medline, Embase and the Cochrane Central Register of Controlled Trials, reference lists of meta-analyses and two clinical trial registries were searched for randomised, placebo-controlled trials of Ca supplements ( ≥ 500 mg/d), with ≥ 100 participants and duration >1 year. The lead authors of eligible trials supplied data on cancer outcomes. Trial-level data were analysed using random-effects meta-analyses and patient-level data using Cox proportional hazards models. A total of sixteen trials were eligible, six had no data available, ten provided trial-level data (n 10,496, mean duration 3·9 years), and of these, four provided patient-level data (n 7221, median duration 3·5 years). In the meta-analysis of trial-level data, allocation to Ca did not alter the risk of total cancer (relative risk 0·95, 95% CI 0·76, 1·18, P= 0·63), colorectal cancer (relative risk 1·38, 95% CI 0·89, 2·15, P= 0·15), breast cancer (relative risk 1·01, 95% CI 0·64, 1·59, P= 0·97) or cancer-related mortality (relative risk 0·96, 95% CI 0·74, 1·24, P= 0·75), but reduced the risk of prostate cancer (relative risk 0·54, 95 % CI 0·30, 0·96, P= 0·03), although there were few events. The meta-analysis of patient-level data showed similar results, with no effect of Ca on the risk of total cancer (hazard ratio 1·07, 95% CI 0·89, 1·28, P= 0·50). Ca supplements without co-administered vitamin D did not alter total cancer risk over 4 years, although the meta-analysis lacked power to detect very small effects, or those with a longer latency.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Breast Neoplasms / epidemiology*
  • Calcium / adverse effects*
  • Colorectal Neoplasms / epidemiology
  • Dietary Supplements / adverse effects*
  • Female
  • Humans
  • Male
  • Proportional Hazards Models
  • Prostatic Neoplasms / epidemiology*
  • Randomized Controlled Trials as Topic
  • Risk
  • Vitamin D / adverse effects


  • Vitamin D
  • Calcium