VDC test kit slider
VDC test kit slider
sperti logo 1
Text size A A A
High contrast on off

Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Calcium supplements and cardiovascular disease: What’s the deal?

Professor Ian Reid of University of Auckland has recently published an excellent review on calcium supplementation and cardiovascular disease.

People are often worried about taking calcium because it’s commonly reported in the media that calcium supplements may increase your risk of cardiovascular disease. In addition, in his review, Dr Reid did find that many people are taking too much calcium, and it is damaging their cardiovascular system.

The article is free to download.

Reid IR.  Cardiovascular effects of calcium supplements. Nutrients. 2013 Jul 5;5(7):2522-9.

During the 1980s and 1990s, calcium supplements became widely used in the prevention and treatment of osteoporosis. Probably a number of factors contributed to their popularity, including evidence that increased intakes were associated with positive calcium balances, and the absence of other clearly effective therapies for managing osteoporosis.

There is now clear evidence that calcium supplements have small positive effects on bone mineral density in randomized controlled trials, and they appear to reduce total fracture risk by as much as 10% (of borderline significance), although they may actually increase hip fractures.

As far as calcium’s effect on cardiovascular health, Reid’s group collected data in 11,921 randomized subjects, 93% of all subjects participating in trials using calcium alone. They found that in this analysis, there was a 27% increase in risk of myocardial infarction (p=0.04) and non-significant upward trends in stroke (relative risk 1.12, p = 0.25) and death (relative risk 1.07, p=0.26).

Calcium treatment was associated with an increased risk of myocardial infarction in people with dietary calcium supplementation above the median of 800 mg/day (hazard ratio 1.85), but no increased risk in those with supplemental calcium intake below the median of 800 mg of calcium per day (hazard ratio 0.98).

The Reid group also carried out a meta-analysis of all studies using either calcium or vitamin D for which cardiovascular event data are available. In this analysis, they found a 24–26% increase in risk of myocardial infarction (p = 0.005) based on a trial population of more than 28,000 subjects. The increase in risk of stroke appears to be less (15%–19%) and sits at the borderline for statistical significance. It did not matter if vitamin D was taken with the calcium.

Reid thinks the mechanism of action by which calcium supplements increase risk of cardiovascular events is that higher doses of calcium supplements produce transient increases in serum calcium, which promotes vessel calcification.

He concluded,

“Individuals considering taking or prescribing calcium supplements are left with a conundrum. There is equivocal evidence of benefit to bone health, which needs to be balanced against steadily increasing evidence of adverse cardiovascular risk. This balance was assessed in the Bolland meta-analysis of calcium monotherapy, which calculated that treating 1000 people with calcium supplements for five years would cause an additional 14 myocardial infarctions, 10 strokes and 13 deaths, while preventing 26 fractures. . . Thus, the available data suggest that the widespread use of calcium supplements in older individuals is doing more harm than good and should be abandoned. . . The absence of a clinically significant association between calcium intake, bone density and fracture risk over the range seen in Western populations, suggests that calcium is not a critical determinant of bone health in most individuals taking a balanced Western diet.”

Compare Professor Reid’s conclusion to a review published last year by Professor Robert Heaney on the very same topic: calcium supplements and cardiovascular disease.

Heaney RP, Kopecky S, Maki KC, Hathcock J, Mackay D, Wallace TC. A review of calcium supplements and cardiovascular disease risk. Adv Nutr. 2012 Nov 1;3(6):763-71.

Along with Dr. John Hathcock and others at the Council for Responsible Nutrition, Professor Heaney highlighted the following in their review:

  • Fifty-four percent of Americans do not meet the estimated average requirement for calcium with diet alone.
  • Emerging evidence suggests that calcium supplementation may be associated reduced risk of the development of colon polyps, cancers, and pre-eclampsia.
  • Over the last two decades, calcium supplementation has been increasing, with 43% of the US population and 70% of older women now using calcium supplements. During this same time, cardiovascular disease has been steadily decreasing.
  • Among 16 studies reviewed in this article involving over 358,000 individuals, there was no indication of a connection between calcium intake and atherosclerotic heart disease or stroke. However, keep in mind that these studies were not all randomized controlled trials like in Reid’s meta-analysis.

In my opinion, based on these two reviews, it is crucial, when and if you decide to supplement with calcium, that you keep the dose below 800 mg/day. And keep in mind many people do not even need that much. The main problem with the studies used in Professor Reid’s meta-analyses was the high dose of calcium used, up to 2,000 mg/day. If you take calcium supplements, don’t take more than 250 to 300 mg at any one time and take it with your meals.

To decide if you need calcium supplements you need to do a dietary analysis on yourself. The easiest way to get enough calcium is to eat dairy, including yogurt and cheese. For vegans, it is a little more difficult (but can be done):

Harvard University Health Services Calcium Content of Common Foods in Common Portions.

The other point I want to make is that bones need more than vitamin D and calcium, a lot more. The chronic low-grade metabolic acidosis present in many of our bodies certainly contributes to osteoporosis.

Dear Dr Cannell: Vitamin D, nutrition and bone health. Posted on October 13, 2011 by John Cannell, MD

Bones need a plethora of minerals, not just calcium and magnesium, but also silica, which is hard to get unless you drink beer or eat whole grain foods, boron, zinc and manganese among others. Vitamin K2 appears to be important as well. If you just take vitamin D and calcium, and have a typical American diet, I suspect your osteoporosis will not improve.

Finally, I think, but cannot prove, a common cause of osteoporosis is widespread subclinical vitamin A toxicity. I recently spearheaded a letter to the Food and Nutrition Board signed by 19 nutrition experts. You can read it here.

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

4 Responses to Calcium supplements and cardiovascular disease: What’s the deal?

  1. Rita and Misty says:

    You’ve written an excellent letter to the FNB/IOM, Dr. Cannell.

    And, I’m always grateful to see those knowledgeable vitamin d physicians and researchers support you. It is quite an impressive list of doctors.

    How I wish the playlist of these supporters might be extended…shall we say grown?

    I am disappointed, though not surprised, to see no Yale physicians/researchers on this list of supporters. :(

    I do know that there are physicians and researchers at University of Connecticut who are vitamin D Receptive (let us call them VDRs…lol).

    By the way, don’t you just love that quote by Goethe??

    “Knowing is not enough; we must apply. Willing is not enough; we must do.”

    I think this is a quote for US to live by…

  2. john9546 says:

    The issue of too much calcium and its relationship with cardiovascular disease may go away with the consideration of getting Vitamin K2 back into our diets. It seems that Vitamin K2 helps calcium to our bones. An excellent discussion on Vitamin K2 can be found is a book by Dr. Kate Rheaume-Bleue “Vitamin K2 and the Calcium Paradox- How a Little-Known Vitamin Could Save Your Life”. Also check out Dr Kate on a YouTube search for her other discussions. Look for Vitamin K2 in the MK-7 form. I also look for food sources of K2 and they can be found in eggs in free range chickens that only eat grass. I occasionally take in Brie which is also a good dietary source of K2. Of course more research is needed with the Vitamin K2 and its relationship with our health, but it looks promising at this time.

  3. Rebecca Oshiro says:

    Dr. C., I really appreciate you distilling what is currently known regarding this topic into practical, actionable advice. Thank you.

  4. rkcannon@yahoo.com says:

    I just got a new book by Fred A. Kummerow, Ph.D. (2014-02-18). Cholesterol is Not the Culprit: A Guide to Preventing Heart Disease (Kindle Location 5). Spacedoc Media, LLC. Kindle Edition.

    Fred will have his 100th birthday this year. He has researched lipids for 70 years and has lots of good info on how cholesterol in not bad etc. But he seems decades behind on his vit D knowledge and says we get TOO MUCH vit D and it is causing atherosclerosis because it causes calcium to circulate and it has to go somewhere- the blood vessels. He only has few references. Comments?

    Huang WY, Kamio A, Yeh S-J, Kummerow F. The influence of vitamin D on plasma and tissue lipids and atherosclerosis in swine. Artery. 1977;3: 439-455.
    266. Holmes RP, Kummerow FA. The relationship of adequate and excessive intake of vitamin D to health and disease. J Am Coll Nutr. 1983;2: 173-199.
    267. MacLaughlin JA, Anderson RR, Holick MF. Spectral character of sunlight modulates photosynthesis of previtamin D3 and its photoisomers in human skin. Science. 1982;216: 1001-1003.
    269. Hass GM, Trueheart RE, Taylor CB, Stumpe M. An experimental histologic study of hypervitaminosis D. Am J Pathol. 1958;34: 395-431.
    270. Mundy GR, Raisz LG. Disorders of bone resorption. In: Bronner F, Coburn JW, eds. Disorder of Mineral Metabolism. Vol III. New York: Academic Press; 1981: 1-66.