The Calcium Conundrum
Doctor of Osteopathic Medicine
Calcium and the Cardiovascular System
There are multiple studies showing that calcium supplementation over prolonged periods of time at doses exceeding 600 mg may increase the risk of cardiovascular mortality. There seems to be a dose relationship in that higher doses infer greater risk.
In a 2021 meta-analysis in the journal Nutrients of randomized controlled trials, it was found that calcium supplementation in doses of 700 -1200 mg (which is often the dose for bone health) was found to be associated with a 15% higher cardiovascular mortality. Another in the British Medical Journal 2011 stratifies risk based on dosages utilized as well as gender. In this study, there was a dose-dependency of cardiovascular mortality in that the greater the dose utilized in the study the higher the risk. This study also showed the effect was statistically significant in men but not women. The dose-dependent risk was still present in women, but the magnitude was less.
The Dose is the Poison
Vascular Calcifications
Renal Calcifications
Keeping it Real
There seems to be some protective effect of getting your calcium from real food. Maybe it is the dose in food, maybe it is the combination of other vitamins and nutrients from the food that is helpful. This may not be possible in many circumstances with dietary limitations and preferences to get the amount needed for bone health. In those cases, supplementation is important but keeping it to 600 mg or less seems to be the risk-benefit ceiling. You can use tables of food sources of calcium such as one found in the Dietary Guidelines For Americans which can be helpful in calculating how many mg of calcium you are getting from food.
Better Together
References
•Katarzyna Maresz. Integr Med (Encinitas) 2015 Feb; 14 (1) 34-39 Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health
•Mark Bolland. BMJ. 2011 April 19; 342 Calcium supplements with or without vitamin D and Risk Of Cardiovascular Events: Re-analysis of the Women’s Health Initiative and MetaAnalysis
•Seung KwonMyung. Nutrients. 2021 Feb; 13(2)368 Calcium Supplements and Risk of Cardiovascular Disease MetaAnalysis of Clinical Trials