Researchers from the Creighton University School of Nursing, in Omaha, Nebraska, studied 2,303 healthy postmenopausal women to determine whether a link between vitamin D and cancer existed.
The treatment group comprised 1,156 women receiving 2,000 International Units (IU) of vitamin D3 and 1,500 milligrams of calcium per day for four years. The 1,147 women in the control group received placebos for the same duration.
Within the study timeframe, 64 women from the placebo group were diagnosed with some form of cancer, while only 49 subjects from the treatment group faced a cancer diagnosis. This represents a small, but significant reduction in the cancer rate for those taking vitamin D3. Further analyses of the levels of 25-hydroxyvitamin D in the blood revealed that the women that developed cancer had substantially lower levels of this vitamin than the subjects that remained healthy.