Calcium plus vitamin D supplementation and the risk of breast cancer.

What Was Tested

The paper reports a study of Vitamin D, K2, Magnesium and Zinc, published as a randomized controlled trial.

Although some observational studies have associated higher calcium intake and especially higher vitamin D intake and 25-hydroxyvitamin D levels with lower breast cancer risk, no randomized trial has evaluated these relationships.

Who Took Part

The abstract describes 1067 patients taking part.

By PubMed's age tags, the people studied were middle-aged adults and older adults, women only.

Baseline serum 25-hydroxyvitamin D levels were assessed in a nested case-control study of 1067 case patients and 1067 control subjects.

How the Study Was Run

The design is described as randomized, double-blind and placebo-controlled.

The patients were allocated by chance, so the Vitamin D, K2, Magnesium and Zinc group and the comparison group should start out alike.

Neither the patients nor the staff measuring them knew who was on Vitamin D, K2, Magnesium and Zinc, so expectations could not easily colour the readings.

The comparison arm used a placebo, so changes seen with Vitamin D, K2, Magnesium and Zinc could be set against what happens without it.

Mammograms and breast exams were serially conducted.

Invasive breast cancer was a secondary outcome.

Associations between 25-hydroxyvitamin D serum levels and total vitamin D intake, body mass index (BMI), recreational physical activity, and breast cancer risks were evaluated using logistic regression models.

What Was Measured

Although some observational studies have associated higher calcium intake and especially higher vitamin D intake and 25-hydroxyvitamin D levels with lower breast cancer risk, no randomized trial has evaluated these relationships.

PubMed files the paper under topics including Body Mass Index, Breast Neoplasms, Calcium Compounds, Carcinoma, Ductal, Breast, Case-Control Studies, Dietary Supplements and Incidence.

What This Means in Plain Language

The paper is a randomized, double-blind and placebo-controlled study of Vitamin D, K2, Magnesium and Zinc in 1067 patients.

With several hundred people or more, it is a fairly large study for this kind of research.

Its findings take up roughly 7 sentences of the abstract and are left out here on purpose; the source paper is the place to read them.

The publication is from 2008 (Journal of the National Cancer Institute), a journal based in United States.

More context: the Vitamin D, K2, Magnesium and Zinc compound page, all human trials.