Relationship of calcium and magnesium intakes with the dietary approaches to stop hypertension score and blood pressure: the International Study of Macro/micronutrients and Blood Pressure

Abstract

Objective: Research investigating calcium and magnesium intakes from the Dietary Approaches to Stop Hypertension (DASH) pattern and other sources in association with blood pressure is limited. We aimed to characterize sources/intake levels of calcium and magnesium in relation to overall diet quality (DASH-score) and determine modification effects with DASH score and blood pressure. Methods: Cross-sectional United States data (average dietary and supplement intake from four 24 h recalls and eight blood pressure measurements) from two separate visits, 2195 men and women (40–59 years) in the International Study of Macro/Micronutrients and Blood Pressure were analysed. Food-based adherence to the DASH diet was estimated. Linear models tested associations between each 1-point DASH score with blood pressure. Participants were stratified by adherence to sex-specific recommended allowance for magnesium and calcium intakes. Effect-modification was tested across DASH-score quintiles and median of urinary sodium. Results: DASH-score was inversely associated with SBP in fully adjusted models (−0.27; 95%CI: −0.38 to −0.15 mmHg). SBP was inversely associated with dietary calcium intake from DASH food groups: −1.54 (95% CI: −2.65 to −0.43) mmHg; calcium intake from other non-DASH food groups: −1.62 (95% CI: −2.94 to −0.29) mmHg. Dietary magnesium intake from DASH food groups (−1.59; 95% CI: −2.79, −0.40 mmHg) and from other non-DASH foods (−1.92; 95% CI: −3.31, −0.53 mmHg) was inversely associated with SBP. Conclusion: A higher DASH score showed a consistent association with lower BP suggesting a relationship between intakes of calcium and Mg with BP regardless of whether the source is part of the DASH diet or not, even when adjusted for supplement intakes. The INTERMAP is registered as NCT00005271 at www.clinicaltrials.gov.