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Can taking calcium cause cardiovascular problems?

Question: Does calcium supplementation increase the risk of cardiovascular disease (CVD)? How do we prescribe calcium safely in those with cardiovascular disease who still need it for supporting bone health? 


Not all evidence points to an increased risk in CVD, and a large body of evidence including a large cohort study of postmenopausal women showed higher calcium intake, in fact, lowered the risk of death due to ischemic heart disease in this population.1 High calcium intake also helps strengthen skeletal tissue and reduce fracture risk.2 Addressing associated vitamin K2 deficiency can also mitigate these risks. 

The study most referenced in regards to the concerns around CVD is a large population study from 2013, tracking almost 220,000 men and 170,000 women for 12 years which found that men, but not women, taking more than 1000mg of supplemental calcium daily had a 20% higher risk of cardiovascular death than those not taking calcium.2

Clinical Reflections:

  • The research outlined above looked only at monotherapy (single nutrient intervention) providing un-ionised calcium (unbound by protein in the blood). Nutrients are directly influenced positively and negatively by the presence of other nutrients and this synergy can make or break clinical outcomes.  
  • The NHMRC recommends daily intake of 1000mg – 1300mg daily for both men and women.3
  • Organic forms of calcium such as calcium citrate are readily absorbed and less affected by medications and hydrochloric acid levels compared to inorganic forms of calcium such as calcium carbonate.*
  • Synergistic nutrients like vitamin K2 can reduce the cardiovascular risks for all population groups.5 

* NOTE:  As with all minerals, it is the form of the mineral that most affects its bio-availability.  Always consult a qualified Naturopath for the right supplement for your needs.

In contrast to calcium, vitamin K2 is associated with the inhibition of arterial calcification and arterial stiffening and intake could be a means of lowering calcium-associated health risks.5 

In the Rotterdam study, which followed 4,807 healthy men and women over the age of 55 for 7-10 years, at least 32 micrograms per day of vitamin K2 (with no K1) reduced the deaths from cardiovascular complications (arterial calcification) by 50%. This also led to a 25% reduction in all-cause mortality and improved elasticity of the blood vessel walls.6 


Osteoblasts produce osteocalcin, which helps take calcium from the circulation and bind it to the bone matrix, in particular to the mineral component of bone, hydroxyapatite. Osteocalcin is inactive and needs vitamin K2 to become fully activated and bind calcium.5

Vitamin K2 also prevents the accumulation of calcium in blood vessel walls. ​Vitamin K–dependent protein, matrix GLA protein (MGP), produced by vascular smooth muscle cells, inhibits calcification and regulates the potentially fatal accumulation of calcium​.5 

Take Home Messages:

  • High-dose monotherapy may increase the risk of cardiovascular complications in men only2  
  • Calcium alone can reduce cardiovascular mortality in postmenopausal women1
  • Even with adequate dietary education, Australian diets are insufficient in both calcium and vitamin K2 5,7 
  • As a default, always supplement calcium with vitamin K2. The synergy of vitamin K2 with calcium has you covered, reduces deaths from CV complications by 50% and improves cardiovascular and bone health.6   

Article courtesy of BioConcepts


  1. Bostick RM, Kushi LH, Wu Y, Meyer KA, Sellers TA, Folsom AR. Relation of calcium, vitamin D, and dairy food intake to ischemic heart disease mortality among postmenopausal women. Am J Epidemiol. 1999;149(2):151-161. doi:10.1093/oxfordjournals.aje.a009781
  2. Xiao Q, Murphy RA, Houston DK, Harris TB, Chow WH, Park Y. Dietary and supplemental calcium intake and cardiovascular disease mortality: The national institutes of health-aarp diet and health study. JAMA Intern Med. 2013;173(8):639-646. doi:10.1001/jamainternmed.2013.3283
  3. NHMRC. Calcium. Nutrient Reference Values. doi:10.1016/s0737-0806(97)80016-0
  4. Straub D. Calcium Supplementation in Clinical Practice: A Review of Forms, Doses, and Indications. Nutr Clin Pract. 2007;22(3):286-296.
  5. Kaneki M. Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health. Clin Calcium. 2005;15(4):605-610.
  6. Kidd PM. Vitamins D and K as pleiotropic nutrients: Clinical importance to the skeletal and cardiovascular systems and preliminary evidence for synergy. Altern Med Rev. 2010;15(3):199-222.
  7. J. A. Pasco, K. M. Sanders, M. J. Henry, G. C. Nicholson, E. Seeman MAK. Calcium intakes among Australian women: Geelong Osteoporosis Study. Intern Med J. 2010;30(1):21-27.