Elsevier

Maturitas

Volume 63, Issue 1, 20 May 2009, Pages 73-78
Maturitas

Use of calcium supplements and the risk of coronary heart disease in 52–62-year-old women: The Kuopio Osteoporosis Risk Factor and Prevention Study

https://doi.org/10.1016/j.maturitas.2009.03.006Get rights and content

Abstract

Background

To analyse prospectively the effect of calcium or calcium + D supplementation on coronary heart disease (CHD) in 52–62-year-old women.

Methods and results

10,555 52–62-year-old women from the population-based Kuopio Osteoporosis Risk Factor and Prevention Study (OSTPRE) who did not have CHD at baseline were followed for nearly 7 years in 1994–2001. Information about use of calcium supplements and health events was obtained from two repeated questionnaires in 1989 and 1994. Information about causes of death during the follow-up was obtained from the Statistics Finland. Information about CHD and other disease morbidity before and during the follow-up was obtained from the Registry of Specially Refunded Drugs of the Finnish Social Insurance Institution (SII). Cox's proportional-hazards models were used to estimate the risk of CHD morbidity related to the use of calcium supplements. At baseline, 2723 women reported current use of calcium or calcium + D supplementation. During the follow-up, CHD was diagnosed in 513 women. Compared to non-users of calcium/calcium + D supplements, the multivariate adjusted hazard ratio (HR) of CHD was 1.24 (95% CI 1.02–1.52) in women who used these supplements. The multivariate adjusted HR for CHD morbidity in postmenopausal women who used calcium/calcium + D supplements was 1.26 (95% CI 1.01–1.57).

Conclusions

Calcium or calcium + D supplementation appears to increase the risk of CHD among women before old age.

Introduction

So far evidence has suggested that vascular disease might be protected by high calcium intakes. In observational studies, calcium has been associated with lower blood pressure [1], [2] and weight loss [3] which might be expected to lower the risk for coronary heart disease and stroke. In the prospective studies, The Nurses’ Health Study [4] and the Health Professionals’ Follow-up Study [5], the risks for developing hypertension were reduced to about 20–25% with calcium supplements. On the other hand, in 2006 Cochrane Database of Systematic Review published a 13-trial meta-analysis which could not find robust evidence of high blood pressure reducing the effects of calcium supplements [6].

Recently, a research group from New Zealand reported a harmful effect of calcium supplementation on vascular event rates in healthy postmenopausal women [7]. Despite previous interventional studies [8], [9], [10] and epidemiological studies suggesting that calcium intake may decrease vascular events, this randomised controlled trial has for the first time questioned the benefits of calcium supplementation on bone due to its possible harmful cardiovascular effects.

Today the use of calcium or calcium + D supplements is very common especially among postmenopausal women who are trying to prevent osteoporosis. Evidence of the trials concerning other effects of calcium is still lacking. The aim of this prospective cohort study is to determine the effect of calcium or calcium + D supplements on the incidence of CHD in women before old age in a population-based design.

Section snippets

Study population

This study is a part of the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) population-based prospective cohort study. The target population primarily consisted of the 14,220 women resident in Kuopio Province and born in 1932–1941 (aged 47–56 years in 1989). The names, addresses and social security numbers of these women were obtained from the National Population Register of Finland. A postal inquiry was sent to 14,121 women, whose postal address could be retrieved in May 1989. In all,

Results

Use of calcium supplements was reported by 2723 (25.8%) of the 10,555 CHD free women at baseline in 1994. The average time of follow-up was 6.55 years (range 0.01–6.75). There were some marked differences between calcium supplement users and non-users (Table 1). Calcium supplements users had a lower BMI (mean 26.3 kg/m2) than non-users, and they also were more often non-smokers or former smokers than calcium supplement non-users. Calcium supplements users had given fewer childbirths and less

Discussion

In the present prospective cohort study, use of calcium or calcium + D supplements tended to increase the risk of CHD during the 6.75 years follow-up among 52–62-year-old women free of CHD at the beginning of the follow-up. The same result was seen in the subgroup of postmenopausal women. Our findings confirm the results of the trial by Bolland et al. [7].

The Finnish Social Insurance Institution carries out the reimbursements for medicines used for severe and chronic illnesses. The National

Conflict of interest

None declared.

Acknowledgments

The authors would like to thank Kuopio University Hospital (EVO-grant), Finnish Menopause Society (grant), National Statistics Finland, Finnish Academy and The Finnish Social Insurance Institution for the support of this work.

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