Latest Data: Calcium Supplements Not Associated With CVD

Pam Harrison

April 22, 2016

Calcium supplements with and without vitamin D have again been shown not to adversely affect cardiovascular disease (CVD) outcomes in men or women between 40 and 69 years of age. The latest analysis to examine this issue includes data from more than half a million individuals.

"Historically, the only side effects of calcium supplementation were an increased risk of indigestion and a very small increased risk of kidney stones, but in recent years, there has been a suggestion from a small number of researchers that calcium supplementation might lead to an increased risk of heart attacks," lead author Nicholas Harvey, MD, University of Southampton, United Kingdom, told Medscape Medical News in an email.

"Using the UK Biobank cohort, we had the opportunity to examine this issue in 500,000 UK men and women in middle to older age, and our results suggest that calcium supplementation ― with or without vitamin D supplementation ― does not increase the risk of cardiovascular events."

The study was presented at the World Congress on Osteoporosis, Osteoarthritis, and Musculoskeletal Diseases, held in Malaga, Spain, April 14–17, 2016.

Reassurance That Calcium/Vitamin D Supplementation Safe

The UK Biobank is a large, prospective cohort involving 502,664 men and women from the United Kingdom. At baseline, the median age of participants was 58 years.

Investigators recorded baseline intake of calcium and vitamin D supplements and linked this to hospital admissions for ischemic heart disease, any CV event, and death through 7 years of follow-up.

They found that 34,890 participants reported taking calcium supplements and that 20,004 were taking vitamin D supplements. Only 2.1% of the group overall were taking both.

In both crude and adjusted analyses for all possible confounders, "There were no associations between use of calcium supplements and risk of incident hospital admission with ischemic heart disease, any cardiovascular event, or death following either admission category," Dr Harvey reported.

Hazard Ratios in the Adjusted Model for Study End Points

Group Ischemic heart disease admission: HR (95% CI)
Death from ischemic heart disease: HR
Women taking calcium vs no calcium intake 1.06 (0.32–1.61; P = .62) 0.71 (0.32–1.61; P = .42)
Men taking calcium vs no calcium intake 1.02 (0.80–1.30; P = .87) 0.92 (0.52–1.62; P = .76)
HR=hazard ratio
95% CI=95% confidence interval

"Results were similar for vitamin D and combination supplementation," he and his colleagues add.

Further adjustment for the use of hormone-replacement therapy in women also did not alter the association between calcium supplementation and CVD end points.

Investigators also pointed out that the findings remained robust when corrected for possible confounders, including age, body mass index, and medication use, and they remained the same whether participants had a history of CVD or not at baseline.

"Calcium supplementation is widely used, including as an adjunct to therapy for osteoporosis," Dr Harvey said in a statement. "Our results, using the largest single study to date, provide reassurance that such supplementation appears safe."

No Evidence for Causal Relationship

There has long been debate about the relative safety of calcium supplements, with physicians recommending that individuals try to obtain the calcium they need from food sources rather than pills.

But because calcium and vitamin D are essential for bone health and the elderly often cannot meet the recommended daily requirements for either nutrient through diet alone, supplements are widely used.

Asked by Medscape Medical News to comment, Bess Dawson-Hughes, MD, director of the bone metabolism laboratory at the United States Department of Agriculture nutrition center on aging and professor of medicine, Tufts University School of Medicine, Boston, Massachusetts, said that there is a lot of material out there right now on the possible causal relationship between calcium supplementation and CVD end points.

The weight of evidence is that there is not an identifiable risk from calcium supplementation in the CV arena, she asserted.

This is particularly important for the elderly, for whom supplementation may be critical for bone health, she added.

"The elderly are not only at risk for osteoporosis but they are also at risk for CVD, so you don't want to have an intervention that prevents one but aggravates the other," Dr Dawson-Hughes said.

"So this is a very important issue, and I'm relieved that the evidence does not support a causal relationship."

Dr Harvey has received personal fees, consultancy fees, lecture fees, and honoraria from Alliance for Better Bone Health, Amgen, MSD, Eli Lilly, Servicer, Shire, Consoling Healthcare, and Internis Pharmaceuticals outside the current work. Dr Dawson-Hughes has received an investigator-initiated research grant from Pfizer and DSM to study the effects of vitamin D on muscle.

World Congress on Osteoporosis, Osteoarthritis and Musculoskeletal Diseases; April 16, 2016; Malaga, Spain. Abstract P311.

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