Over the past six years, there have been published trials raising concerns regarding calcium supplementation and excess risk for myocardial infarction and stroke. While the findings have not been consistent, a recent updated systematic review and meta-analysis on the effects of calcium intake from diet and supplements, either alone or with vitamin D, on the risk for cardiovascular disease in generally healthy adults, provides some clarification.1
The researchers analyzed four randomized trials and 27 observational studies. Calcium supplementation ranged from 400 mg/day to 1,600 mg/day.
The key points of the analysis were the following:
- Calcium intake with or without vitamin D either from food or supplements had no helpful or harmful risk for cardiovascular events in healthy adults.
- Calcium from either food or supplements that did not exceed the “tolerable upper level of intake” is safe in relationship to cardiovascular health.
- These conclusions were primarily from observational studies. The two previously published meta-analyses that showed some excess risk in randomized trials were considered unreliable by the current authors and reviewers.
- Dietary sources of calcium may be preferred over supplements because it is easier to avoid any excess. Excess calcium may cause gastrointestinal side effects, increase the risk for kidney stones and interfere with absorption of medications.
This issue has been confusing the last several years. From a clinical perspective there was really never a reason to be concerned. It is understood that the guidelines from the Institute of Medicine of 1,000 mg-1,200 mg/day of calcium is meant to be total dietary and supplemental calcium, not just supplements. Most adults in the U.S. have a dietary calcium intake of 500 mg-1,000 mg/day, which means supplementing an additional approximate 500 mg/day in pill form is recommended. It was never intended that we eat 1,000 mg/day and then take another 1,000 mg-1,200 mg/day.
It’s important to communicate this fact to our patients so they are not concerned when hearing about potential dangers associated with calcium supplements. It’s also important to direct patients to look at the amount of calcium in all of their dietary supplements to determine how much calcium they are actually taking on a daily basis. Estimating daily dietary calcium intake can be done by looking at food charts. A general guideline has been to count 250 mg/day for the non-dairy and non-soy foods and then allow 300 mg per serving of dairy, tofu or soy milk.
Calcium is an important mineral for health. When total intake is managed appropriately, it is also very safe.2,3
Dr. Tori Hudson directs the curriculum for post-graduate training in women's health at the Institute of Women's Health and Integrative Medicine, and is the director of product research and education for VITANICA. For more information on Dr. Hudson visit http://drtorihudson.com/.
- Chang M, et al. Calcium intake and cardiovascular disease risk: An updated systematic review and meta-analysis. Ann Intern Med 2016; Oct 25 (epub)
- Kopecky SL, et al. Lack of evidence linking calcium with or without vitamin D supplementation to cardiovascular disease in generally healthy adults. A clinical guideline from the National Osteoporosis Foundation and American Society for Preventive Cardiology. Ann Intern Med 2016;Oct 25 (epub)
- Margolis K and Manson J. Calcium supplements and cardiovascular disease risk: What do clinicians and patients need to know? Ann Intern Med 2016; Oct 25 (epub)