High magnesium intake lowers colon cancer risk in women

The findings from a study of U.S. women support the results of an earlier study of Swedish women, that dietary magnesium intake is inversely associated with colon cancer risk. Still, the authors note that a clinical trial is needed to confirm that the benefit is due to magnesium intake rather than some related factor.

As reported in the American Journal of Epidemiology for February, Dr. Aaron R. Folsom and Dr. Ching-Ping Hong, from the University of Minnesota in Minneapolis, used food frequency questionnaires to assess magnesium intake in 35,196 Iowa women, between 55 and 69 years old at baseline, who were followed for colorectal cancer from 1986 through 2002.During follow-up, 1112 women developed colorectal cancer, the report indicates. There was a nonsignificant trend toward decreased colorectal cancer risk as magnesium intake increased.Further analysis showed that high magnesium intake offered no apparent protection against rectal cancer, but did significantly decrease the risk of colon cancer (p = 0.04). Women in the highest quintile of intake were 23% less likely to develop colon cancer than their peers in lowest quintile of intake.In contrast, the Swedish study found that high magnesium intake was inversely associated with the risks of both colon and rectal cancer. The reasons for this difference are unclear, the authors note. Magnesium has been hypothesized to cut the risk of colon cancer by reducing oxidative stress, improving insulin sensitivity, or through mechanisms that reduce colon epithelial cell proliferation, the authors note. (Source: Am J Epidemiol 2006;163:232-235: Reuters Health: Oncolink: February 2006.)