Magnesium intake in relation to risk of colorectal cancer in women.

CONTEXT Animal studies have suggested that dietary magnesium may play a role in the prevention of colorectal cancer, but data in humans are lacking. OBJECTIVE To evaluate the hypothesis that a high magnesium intake reduces the risk of colorectal cancer in women. DESIGN, SETTING, AND PARTICIPANTS The Swedish Mammography Cohort, a population-based prospective cohort of 61,433 women aged 40 to 75 years without previous diagnosis of cancer at baseline from 1987 to 1990. MAIN OUTCOME MEASURE Incident invasive colorectal cancer. RESULTS During a mean of 14.8 years (911 042 person-years) of follow-up, 805 incident colorectal cancer cases were diagnosed. After adjustment for potential confounders, we observed an inverse association of magnesium intake with the risk of colorectal cancer (P for trend = .006). Compared with women in the lowest quintile of magnesium intake, the multivariate rate ratio (RR) was 0.59 (95% confidence interval [CI], 0.40-0.87) for those in the highest quintile. The inverse association was observed for both colon (RR, 0.66; 95% CI, 0.41-1.07) and rectal cancer (RR, 0.45; 95% CI, 0.22-0.89). CONCLUSION This population-based prospective study suggests that a high magnesium intake may reduce the occurrence of colorectal cancer in women.