Calcium intake not associated with CVD risk

In generally healthy adults, there was no link between calcium intake, with or without vitamin D supplementation, and risk for cardiovascular disease, according to findings published in the Annals of Internal Medicine.

Mei Chung, MPH, PhD, from Tufts University, and colleagues reviewed CVD risk and calcium intake on behalf of the National Osteoporosis Foundation and the American Society for Preventive Cardiology.

The researchers conducted a systematic review and meta-analysis of 27 observational studies identified via databases such as MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials to investigate CVD risk. They noted that previous research on the effects of high calcium intake was conflicted.

"Although adequate calcium and vitamin D intake is critical for maintaining bone health, the role of calcium and vitamin D supplementation in older adults is unclear," Chung and colleagues wrote. "Some systematic reviews showed that combined calcium and vitamin D supplementation reduced the risk for fractures in older adults, whereas more recent systematic reviews reported inconsistent effects for fractures across randomized, controlled trials. Experts have raised concerns about a potential effect of a high intake of calcium (with or without vitamin D) from foods and supplements on cardiovascular disease (CVD) outcomes."

Results demonstrated no significant difference between patients who received calcium supplements or patients who received calcium and vitamin D and those who received placebo in terms of risk for CVD events or mortality.

In addition, researchers reported inconsistent dose-response relationships between calcium intake and risk for stroke or stroke mortality and calcium intake and cardiovascular mortality.

"We conclude that calcium intake (from either food or supplement sources) at levels within the recommended tolerable upper intake range (2,000 to 3,000 mg/d) are not associated with CVD risks in generally healthy adults," Chung and colleagues wrote. "Although a few trials and cohort studies reported increased risks with higher calcium intake, risk estimates in most of those studies were small (±10% relative risk) and not considered clinically important, even if they were statistically significant."

Stephen L. Kopecky, MD, from the Mayo Clinic, and colleagues, utilized the study findings to develop a clinical guideline.

"The [National Osteoporosis Foundation] and [American Society for Preventive Cardiology] adopt the position that there is moderate-quality evidence (B level) that calcium with or without vitamin D intake from food or supplements has no relationship (beneficial or harmful) with the risk for cardiovascular and cerebrovascular disease, mortality, or all-cause mortality in generally healthy adults at this time," they wrote. "In light of the evidence available to date, calcium intake from food and supplements that does not exceed the tolerable upper level of intake (defined by the National Academy of Medicine as 2,000 to 2,500 mg/d) should be considered safe from a cardiovascular standpoint."

In an accompanying editorial, Karen L. Margolis, MD, MPH, from the HealthPartners Institute, and JoAnn E. Manson, MD, DrPH, from Brigham and Women's Hospital and Harvard Medical School, reported that the findings serve as an addendum to recommendations issued by the Institute of Medicine, and the study "breaks some new ground in its analysis of 27 observational studies.”

"The authors used linear and nonlinear dose-response metaregressions to overcome a limitation that is particularly important in pooling studies of nutrients with widely varying intake levels in the reference groups," they wrote. "The results showed no consistent dose-response relationships between dietary or total calcium intake and risks for stroke, cardiovascular, or ischemic heart disease mortality, which were the most common outcomes reported by the studies.”

Margolis and Manson wrote that physicians and patients can incorporate these findings in a variety of ways.

“Although the preponderance of evidence does not support cardiovascular adverse effects, dietary sources of calcium are preferable to supplements for other reasons,” they wrote. “Calcium supplements may increase kidney stone formation, whereas dietary calcium intake reduces the risk for kidney stones, a painful condition that affects 10% to 20% of adults. No evidence exists that consuming more calcium than the recommended dietary allowance will result in better bone health or any other health benefits.”

The authors also noted that adults can achieve the median dietary calcium intake by consuming two to three servings of high-calcium foods, which include dairy products, tofu and leafy greens.

“Supplements may be used to make up but not exceed the gap between dietary intake and the recommended intake level; however, most persons require no more than 500 mg of supplemental calcium to meet their daily needs, if not met by diet alone,” they concluded. “Achieving the recommended intakes of vitamin D (600 IU/d for adults up to age 70 and 800 IU/d for those aged 70 or older) also is essential. Based on the totality of evidence for both calcium and vitamin D, more is not better.” – by Chelsea Frajerman Pardes

Disclosures: Chung reports no relevant financial disclosures. Please see the full study for a complete list of all other authors' relevant financial disclosures.

References:

Chung M, et al. Ann Intern Med. 2016;doi:10.7326/M16-1165.
Kopecky SL, et al. Ann Intern Med. 2016;doi:10.7326/M16-1743.
Margolis KL, Manson JE. Ann Intern Med. 2016;doi:10.7326/M16-2193.