Magnesium intake is inversely associated with risk of obesity in a 30-year prospective follow-up study among American young adults

Purpose Although laboratory studies suggest a potential role of magnesium (Mg) in weight regulation, human studies relating Mg intake to body weight are limited. This study sought to prospectively examine the association between Mg intake and incidence of obesity and related anthropometric and biochemical indicators. Methods The Coronary Artery Risk Development in Young Adults (CARDIA) study recruited 5115 American young adults, aged 18-30 years, at baseline in 1985-6, and re-examined them in eight follow-ups. Incident obesity was defined as body mass index (BMI) >= 30 kg/m(2). Dietary Mg intake was collected using the CARDIA Diet History at baseline and exam years 7 and 20. Results During the 30-year follow-up, 1675 incident cases of obesity were identified. After adjustment for potential confounders, Mg intake was inversely associated with incidence of obesity. The multivariable-adjusted hazard ratios (95% confidence interval) from quintile 1 (Q1) (lowest intake group) to quintile 5 (Q5) (highest intake group) were 1 (referent), 0.86 (0.74, 1.00), 0.83 (0.71, 0.97), 0.55 (0.46, 0.66), and 0.49 (0.40, 0.60); P for trend < 0.01. Consistently, Mg intake was inversely associated with the levels of BMI, triceps skinfold, suprailiac skinfold, subscapular skinfold, fasting insulin, and C-reactive protein. The observed associations were not materially modified by age, sex, race, or BMI at baseline. In addition, the intakes of foods rich in Mg, including whole grains, nuts and seeds, legumes, and dark-green vegetables, were associated with lower incidence of obesity. Conclusions This longitudinal study suggests that Mg intake is inversely associated with incidence of obesity.