Calcium's role in cancer

By Karen Collins, R.D.
Special to MSNBC

For some time, nutrition researchers have thought that sufficient amounts of calcium in the diet may protect people from colon cancer. The results of studies vary, however. Two new explanations for this inconsistency have been offered: First, the source of calcium may make a difference. Second, inherited differences in the “receptors” on cells that process nutrients could safeguard some people more than others.

There are still good theoretical reasons linking calcium consumption to a reduced risk of colon cancer, however. These reasons tend to be supported by both laboratory and human studies.

One of the most recent analyses pooled data from ten different studies in five countries. People who consumed the most calcium had a 20 percent lower risk of colorectal cancer than those people who consumed the least calcium.

In another study, women who met or nearly met current adult calcium recommendations reduced their risk of colorectal cancer almost 30 percent compared to those who ate half the recommended amount. In this study, total calcium consumption was more significant than dairy product consumption, and vitamin D was not linked to risk.

In addition to these studies, others have shown from 15 to 30 percent drops in colorectal cancer risk for people with high calcium consumption.