Recently, two cohort studies among women indicated that magnesium intake is inversely associated with risk of colorectal cancer; evidence among men is lacking. The Netherlands Cohort Study on Diet and Cancer (NLCS) started in 1986 (n=58,279 men and 62,573 women). Data were processed and analyzed using the case-cohort approach, enumerating the cases for the entire cohort, and estimating the person-years at risk in the cohort using a subcohort. This subcohort was randomly sampled from the entire cohort immediately after the baseline measurement and is being followed up for vital status. Follow-up for cancer was established by annual record linkages with the Netherlands Cancer Registry and the nationwide pathology registry. After 13.3 years of follow-up, 2328 colorectal cancer cases were available. Energy-adjusted magnesium intake was nonsignificantly inversely related to risk of colorectal (particularly colon) cancer in men and women in multivariate analysis, controlling for age, family history of colorectal cancer, BMI, physical activity, energy-adjusted intakes of fat, fiber, calcium, folate, beta-carotene, vitamins E and B6, alcohol and energy intake. After stratification according to BMI, inverse associations were observed in overweight subjects only and were statistically significant for colon and proximal colon cancer (p-trend, 0.05 and 0.02, respectively), with rate ratios for increasing quintiles of magnesium of 1.0, 0.72, 0.69, 0.60 and 0.67 for colon cancer and 1.0, 0.69, 0.65, 0.48 and 0.54 for proximal colon cancer, respectively. The data support an inverse association between magnesium intake and colon cancer risk in men and women, particularly among overweight subjects. Magnesium might be beneficial through decreasing insulin resistance in overweight subjects.
[Fifth AACR International Conference on Frontiers in Cancer Prevention Research, Nov 12-15, 2006]