Analysis of data from the third National Health and Nutrition Examination Survey (NHANES III) indicated that calcium is involved in cardiovascular health, with an increased risk of cardiovascular death linked to low calcium levels.
“Overall, we found an increased risk of cardiovascular death when serum calcium levels were less than 1.16 mmol/L compared to 1.16–1.31 mmol/L, but for women, there was an increased [ischemic heart disease] mortality among women with high serum calcium levels (greater than 1.31 mmol/L),” wrote the researchers.
“No associations were found between cardiovascular death and dietary or supplement calcium intake.
“However, there was a protective effect for total calcium intake of 1300–2000 mg/day and death from IHD among men.”
Researchers from King's College London (UK), Uppsala University (Sweden), Helmholtz Zentrum München (Germany), the University of Zurich (Switzerland), and Universidad Peruana de Ciencias Aplicadas (Peru), report their findings in PLoS One.
Controversy
Several reports in the literature have questioned the safety of calcium supplements taken to reduce the risk of osteoporosis in terms of a possible increase in the risk of cardiovascular problems. Most recently, a report in JAMA Internal Medicine concluded that high intakes of calcium from supplements may increase the risk of cardiovascular disease for men, but not women.
That study, a reanalysis of data from the National Institutes of Health-AARP Diet and Health Study, was described as “inappropriate” by a leading dietary supplements trade association, because it was initially designed to examine the potential associations between diet and cancer.
Taylor Wallace, PhD, senior director, scientific and regulatory affairs for the Council for Responsible Nutrition (CRN), told us in February: “They are mining data from this cohort to address a question that it was not designed to answer.”
On the other hand, a recent report from the Institute of Medicine concluded that “evidence from clinical trials currently does not support an effect of calcium intake on risk of cardiovascular disease”.
In addition, Harvard Medical School researchers reported in November no link between calcium supplements and an increased risk of artery calcification, according to analysis of data from the Framingham Offspring Study published in the American Journal of Clinical Nutrition.
New data
For the new study, data from 20,024 people were analyzed to estimate the risk of cardiovascular death. During the course of the study, 10% of the people died of heart disease.
People in the bottom 5% for calcium levels had a 50% increased risk of dying from heart disease.
An increase in risk for women with the very highest levels of calcium was observed for death from ischemic heart disease. On the other hand, low calcium levels were associated with an increased risk of IHD mortality
“The current study suggests that calcium is involved in cardiovascular health,” wrote the researchers.
“However there was no strong evidence for an association between calcium supplement usage and cardiovascular death indicating that calcium supplement usage may be a marker of healthy life style despite adjustments for comorbidities, smoking, alcohol consumption, and levels of physical activity.”
Source: PLoS One
Volume 8, Number 4, e61037, doi: 10.1371/journal.pone.0061037
“Calcium Intake and Serum Concentration in Relation to Risk of Cardiovascular Death in NHANES III”
Authors: M. Van Hemelrijck, K. Michaelsson, J. Linseisen, S. Rohrmann