Acute effect of calcium citrate on serum calcium and cardiovascular function.
Study Goal
The researchers aimed to determine whether an acute rise in serum calcium following calcium supplement administration is associated with adverse changes in cardiovascular function.
Results Summary
The study found that acute calcium supplementation led to reduced arterial wave reflection and increased myocardial perfusion, suggesting potential cardiovascular benefits rather than risks. No significant changes were observed in arterial stiffness or endothelial function.
Population
25 volunteers (16 female, age 60.3 ± 6.5 years, BMI 25.7 ± 2.7 kg/m²) not taking calcium supplements.
Effective Dosage
Single oral dose of 1000 mg calcium citrate.
Duration
Acute (3-hour post-administration assessment).
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
Calcium supplements | increase | cardiovascular events | - | - | associated with an increased risk | #1 |
a single oral dose of 1000 mg calcium citrate | increase | Total serum calcium | 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements | 0.10 ± 0.07 mmol/L | acutely increased | #2 |
a single oral dose of 1000 mg calcium citrate | increase | ionized serum calcium | 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements | 0.06 ± 0.03 mmol/L | acutely increased | #3 |
calcium citrate administration | decrease | augmentation index (AIx) | 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements | from a median of 29.7% (23.8% to 34.0%) to 26.4% (22.7% to 34.0%) | a fall in | #4 |
calcium citrate administration | increase | subendocardial viability ratio (SEVR) | 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements | from 163% (148% to 174%) to 170% (149% to 185%) | an increase in | #5 |
calcium citrate administration | no change | pulse wave velocity (PWV) | 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements | no significant change | not significantly altered | #6 |
calcium citrate administration | no change | reactive hyperemia index (RHI) | 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements | no significant change | not significantly altered | #7 |
the acute increase in serum calcium following calcium supplement administration | decrease | arterial wave reflection | - | - | associated with reduced | #8 |
the acute increase in serum calcium following calcium supplement administration | increase | myocardial perfusion | - | - | associated with a marker of increased | #9 |
Calcium supplements have been associated with an increased risk of cardiovascular events. However, the validity of these findings has been questioned. A major concern is that the mechanism underlying an increase in cardiovascular events has not been demonstrated. Calcium initiates cardiac and vascular contraction following influx of calcium into cardiac and smooth muscle from extracellular fluid. We have investigated whether the acute rise in serum calcium following calcium supplement administration is associated with adverse changes in cardiovascular function. In an open interventional study, we recruited 25 volunteers (16 female, age 60.3 ± 6.5 years, body mass index 25.7 ± 2.7 kg/m2) from the community who were not taking calcium supplements. Participants were studied before and 3 hours after a single oral dose of 1000 mg calcium citrate. We assessed well-validated markers of arterial stiffness (pulse wave velocity [PWV]), arterial wave reflection (augmentation index [AIx]), and myocardial perfusion (subendocardial viability ratio [SEVR]) by pulse wave analysis and endothelial function (reactive hyperemia index [RHI]) by peripheral arterial tonometry. Total and ionized serum calcium were acutely increased by 0.10 ± 0.07 and 0.06 ± 0.03 mmol/L, respectively, 3 hours after calcium citrate administration (p < 0.0001 for both comparisons). Following administration of calcium citrate there was a fall in AIx from a median of 29.7% (23.8% to 34.0%) to 26.4% (22.7% to 34.0%, p = 0.03) and an increase in SEVR from 163% (148% to 174%) to 170% (149% to 185%, p = 0.007). PWV and RHI were not significantly altered. The change in total calcium was negatively correlated with the change in AIx (r = -0.48, p = 0.02). In summary, the acute increase in serum calcium following calcium supplement administration is associated with reduced arterial wave reflection and a marker of increased myocardial perfusion. If maintained long-term, these changes would be expected to reduce cardiovascular risk. Acute serum calcium-mediated changes in these parameters of cardiovascular function are unlikely to underlie an association between calcium supplementation and cardiovascular events.