Serum calcium, even within normal range, is associated with blood pressure with a potential influence of calcium intake

Abstract Context Even within the physiological range, serum calcium (sCa++) may influence vascular tone and blood pressure (BP); however, the potential modulatory role of dietary calcium intake remains unclear. Objective To investigate the association between sCa²⁺ and BP (including central BP) and to assess whether calcium intake affects this relationship. Methods sCa²⁺ was measured in patients referred for suspected secondary hypertension (VerHyperReg; n=81) and in two population-based cohorts: the Malmö Preventive Project (MPP; n=18,240) and the UK Biobank (UKB; n≈330,000). Calcium intake was assessed in the Malmö Diet and Cancer Study (MDC; n=28,098) and in a subsample of MPP participants (MPPxMDC; n=4,095). Multivariable regression models were used to analyze the associations. Results In MPP and UKB, sCa²⁺ was positively associated with systolic and diastolic BP (even within the normal range). In VerHyperReg, sCa²⁺ was associated with central systolic BP. In the MDC, higher calcium intake was inversely associated with BP. In MPPxMDC, sCa²⁺ was positively associated with systolic BP in the lower three quartiles of intake, whereas this association was reversed in the highest quartile. Conclusion Serum calcium levels within the normal range are positively associated with BP. Increased dietary calcium intake may attenuate this relationship, thus suggesting a modulatory role in BP regulation. Further investigations are warranted.