BackgroundTo test whether dietary magnesium is associated with 10-year risk of a first hard atherosclerotic cardiovascular disease event. MethodsIn this cross-sectional study, a total of 2980 participants, aged 40 to 79 years, from the National Health and Nutrition Examination Survey 1999–2018 were analyzed. The association between dietary magnesium and 10-year risk of a first hard atherosclerotic cardiovascular disease (ASCVD) event was assessed following adjustment for clinical risk factors, including sex, age, race, educational level, body mass index (BMI), alcohol drinking, smoking, systolic blood pressure (SBP), diastolic blood pressure (DBP), hypertension treated or not, diabetes and low density lipoprotein cholesterol (LDL-C), total energy and dietary fiber. We performed multivariate linear regression models and smooth curve fittings to evaluate the associations between dietary magnesium and 10-year risk of a first hard atherosclerotic cardiovascular disease event. ResultsWe observed a significant inverse association between dietary magnesium and predicted 10-year risk of a first hard atherosclerotic cardiovascular disease event (β=-0.01, [95% CI: -0.01, -0.00], P = 0.0256). We divided the 10-year risk into two categories, with a statistically significant reduction of ASCVD risk when the 10-year risk ≥7.5% (β=-0.01, [95% CI: -0.01, -0.00], P = 0.0440). ConclusionsDietary magnesium intake was inversely associated with the predicted 10-year risk of a first hard atherosclerotic cardiovascular disease event.