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

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.

To investigate the association between sCa²⁺ and BP (including central BP) and to assess whether calcium intake affects this relationship.

sCa²⁺ was measured in patients referred for suspected secondary hypertension (VerHyperReg; n = 81) and in 2 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 (MPP×MDC; n = 4095). Multivariable regression models were used to analyze the associations.

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 MPP×MDC, sCa²⁺ was positively associated with systolic BP in the lower 3 quartiles of intake, whereas this association was reversed in the highest quartile.

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.