Larsson SC et al. (2005) Magnesium intake in relation to risk of colorectal cancer in women. JAMA 293: 86–89

A large, prospective study from Sweden has suggested that a high intake of magnesium lowers the risk of colorectal cancer in women. These findings reflect experimental studies suggesting that magnesium may inhibit colorectal carcinogenesis.

Larsson et al. used questionnaire data provided by 61,433 women from the Swedish Mammography Cohort, which was established between 1987 and 1990. Using the Swedish National Food Administration Database, the investigators estimated the energy-adjusted daily magnesium intake of each participant and then categorized the women into quintiles on this basis. During a mean follow-up of 14.8 years, a statistically significant, inverse relationship was observed between magnesium intake and colorectal cancer risk (P = 0.006). Women in the highest quintile of magnesium intake had a lower risk of colorectal cancer than those in the lowest quintile (multivariate rate ratio 0.59, 95% CI 0.40–0.87), and a similar pattern was observed when colon cancer and rectal cancer were analyzed separately.

These results support the idea that increasing consumption of foods that contain magnesium—such as fruit and vegetables, whole grain foods and beans—can reduce the risk of colorectal cancer. The authors note, however, that randomized studies will be needed to examine the safety and potential benefits of magnesium supplementation.