Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial

Am J Clin Nutr. 2007 Jun;85(6):1586-91. doi: 10.1093/ajcn/85.6.1586.

Abstract

Background: Numerous observational studies have found supplemental calcium and vitamin D to be associated with reduced risk of common cancers. However, interventional studies to test this effect are lacking.

Objective: The purpose of this analysis was to determine the efficacy of calcium alone and calcium plus vitamin D in reducing incident cancer risk of all types.

Design: This was a 4-y, population-based, double-blind, randomized placebo-controlled trial. The primary outcome was fracture incidence, and the principal secondary outcome was cancer incidence. The subjects were 1179 community-dwelling women randomly selected from the population of healthy postmenopausal women aged >55 y in a 9-county rural area of Nebraska centered at latitude 41.4 degrees N. Subjects were randomly assigned to receive 1400-1500 mg supplemental calcium/d alone (Ca-only), supplemental calcium plus 1100 IU vitamin D3/d (Ca + D), or placebo.

Results: When analyzed by intention to treat, cancer incidence was lower in the Ca + D women than in the placebo control subjects (P < 0.03). With the use of logistic regression, the unadjusted relative risks (RR) of incident cancer in the Ca + D and Ca-only groups were 0.402 (P = 0.01) and 0.532 (P = 0.06), respectively. When analysis was confined to cancers diagnosed after the first 12 mo, RR for the Ca + D group fell to 0.232 (CI: 0.09, 0.60; P < 0.005) but did not change significantly for the Ca-only group. In multiple logistic regression models, both treatment and serum 25-hydroxyvitamin D concentrations were significant, independent predictors of cancer risk.

Conclusions: Improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00352170.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Calcifediol / blood
  • Calcium / therapeutic use*
  • Dietary Supplements*
  • Double-Blind Method
  • Female
  • Fractures, Bone / prevention & control
  • Humans
  • Incidence
  • Kaplan-Meier Estimate
  • Logistic Models
  • Middle Aged
  • Neoplasms / epidemiology
  • Neoplasms / prevention & control*
  • Vitamin D / therapeutic use*

Substances

  • Vitamin D
  • Calcifediol
  • Calcium

Associated data

  • ClinicalTrials.gov/NCT00352170