Abstract 5309: Dietary magnesium is inversely associated with colorectal cancer risk in the Atherosclerosis Risk in Communities study

Background: Magnesium is a key nutritional mineral required for the regulation of numerous biochemical reactions throughout the body. Main food sources of magnesium include whole grains, nuts, and green vegetables, but more than 50% of Americans do not currently meet their daily recommended magnesium intake. Prior research has shown that those deficient in magnesium have increased susceptibility to oxidative stress and chronic inflammation, leading to endothelial dysfunction and potentially stimulating cancer cell proliferation and invasiveness. Previous epidemiological studies suggested a link between a diet high in magnesium and reduced CRC, especially among women. The American Cancer Society underscores the importance of clarifying the role of dietary magnesium in CRC development overall and by gender. Thus, we prospectively examined the associations between dietary magnesium intake and CRC risk in the ARIC study, overall, and separately in men and women. Methods: The ARIC study followed 15,792 men and women (45-64 years old at baseline) for cancer occurrence from 1987-2006. Participants received medical examinations and completed questionnaires at 4 visits; food frequency data were collected at Visit I (1987-89) and magnesium intake estimated. Cox proportional hazards regression was used to calculate hazard ratios (HR) and 95%CI for CRC associated with dietary magnesium intake in quartiles using two models: Model 1 adjusted for baseline age, race, center, sex, energy intake, BMI, and physical activity. Model 2 included Model 1 covariates as well as intake of alcohol, dietary calcium, dietary fiber, aspirin, CRP levels, and cigarette smoking. Results: The analytic cohort (n=14,160, 54.5% women, 27.3% black and 72.7% white, 45-64 years at baseline) was followed for a median of 15.4 years; 315 CRC cases were identified. Since only the highest quartile of dietary magnesium intake met US recommendations (>300 mg/day), we examined the highest quartile versus the 3 lowest quartiles combined (reference category). In Model 1, the highest quartile of dietary magnesium was associated with lower CRC risk: HR (95%CI) =0.68 (0.47-0.99). The inverse association between magnesium and CRC persisted in Model 2 (HR=0.70; 95% CI 0.48, 1.02). The association followed a similar trend after stratification by colon and rectal cancer cases (HR(95% CI) =0.72 (0.48-1.08) and HR(95% CI)=0.49 (0.23-1.06), respectively) and by men and women (HR(95% CI)=0.75 (0.42-1.21) and HR(95% CI)=0.63 (0.36-1.12) respectively). There was no interaction of dietary magnesium intake with dietary calcium intake, alcohol consumption use or dietary fiber. Conclusion: Our findings corroborate an inverse association between higher dietary magnesium intake and CRC risk, with similar associations observed in men and women. Support: NHLBI, NCI, NPCR Citation Format: Guillaume C. Onyeaghala, Elizabeth Polter, Pamela L. Lutsey, Aaron R. Folsom, Corrine E. Joshu, Elizabeth A. Platz, Anna E. Prizment. Dietary magnesium is inversely associated with colorectal cancer risk in the Atherosclerosis Risk in Communities study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5309. doi:10.1158/1538-7445.AM2017-5309