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What Is the Story on Calcium Supplements?

Studies suggest that calcium supplements don't prevent osteoporosis and broken bones, and may even have troubling side effects.
What Is the Story on Calcium Supplements?
Supplements tablets

When the medical experts change their minds, it can be confusing for the rest of us. One such flip-flop that has puzzled a lot of people concerns calcium supplements.

For years, doctors urged their older patients, especially women, to take high doses of calcium to maintain bone strength. It seemed logical: after all, bones contain calcium, so why wouldn’t you take extra calcium if you wanted to avoid weak and broken bones?

The only trouble is that recommendations based on theory don’t always work out so well in practice. Recent studies of calcium intake from food or supplements do not show that extra calcium protects people from osteoporosis or bone fracture. While people who get too little calcium may be at risk, taking high-dose calcium supplements may be counterproductive (Maturitas, Jan. 2018). No wonder this reader has questions:

What Is the Story on Calcium Supplements?

Q. Could you please comment about the news report a few months ago pertaining to calcium supplements? The study showed that calcium did not help older people’s bones and that it could actually be harmful with side effects like heart attacks.

Now I am afraid to take my 1,500 mg of calcium with vitamin D per day and have cut the dose down to 500 mg of calcium a day. Am I doing the right thing? I am female age 73.

A. You have mentioned a source of great confusion for many people. For years, doctors have been urging older people (especially women) to take high doses of calcium (1,200 mg/day) to prevent bone loss and avoid fractures.

Theory Falls Short:

The only problem with that recommendation is that it was based on theory. When scientists reviewed studies of calcium intake and the risk of bone fracture, they found no association between the two. They concluded, “there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fractures. Evidence that calcium supplements prevent fractures is weak and inconsistent.” (BMJ, Sep. 29, 2015).

Downsides of Calcium Supplements:

Calcium supplements have some downsides. Too much calcium can increase the chance of kidney stones (New England Journal of Medicine, Feb. 16, 2006).  In addition, people who take calcium supplements are at a greater risk of heart attack (BMJ, July 29, 2010).

Another question is whether people absorb the calcium from supplements efficiently. That is what this reader wonders.

Can Liquid Calcium Supplements Solve Absorption Problems?

Q. I have heard for years that calcium tablets go through your system without ever dissolving and therefore do no good. Is there a liquid calcium on the market that might be better assimilated in my body?

A. Some calcium tablets are poorly formulated and don’t dissolve well. As a consequence, you can’t absorb the nutrient from them effectively. Others, however, work well to provide the mineral.

ConsumerLab.com, which tests many supplements, has found that liquid calcium citrate (Bluebonnet) is absorbed well and makes a reasonable calcium supplement. It is less likely to pose a choking hazard for people who have trouble swallowing large tablets.

A meta-analysis of randomized controlled trials concludes that “dairy products fortified with calcium and vitamin D could have a favorable effect on bone mineral density” (Food & Function, Dec. 1, 2020). As a result, that might offer another way of getting extra calcium in liquid form.

Learn More:

If you would like to learn more about the pros and cons of calcium supplements and other ways to reduce the possibility of osteoporosis, you may wish to listen to our hour-long interview with Dr. Walter Willett of Harvard School of Public Health and Michael Castleman, co-author of Building Bone Vitality.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
  • Cano A et al, "Calcium in the prevention of postmenopausal osteoporosis: EMAS clinical guide." Maturitas, Jan. 2018. DOI: 10.1016/j.maturitas.2017.10.004
  • Bolland MJ et al, "Calcium intake and risk of fracture: systematic review." BMJ, Sep. 29, 2015. doi: https://doi.org/10.1136/bmj.h4580
  • Jackson RD et al, "Calcium plus vitamin D supplementation and the risk of fractures." New England Journal of Medicine, Feb. 16, 2006. DOI: 10.1056/NEJMoa055218
  • Bolland MJ et al, "Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis." BMJ, July 29, 2010. doi: https://doi.org/10.1136/bmj.c3691
  • Liu C et al, "Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials." Food & Function, Dec. 1, 2020. DOI: 10.1039/d0fo00787k
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