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Why You Should Take Calcium Twice, Daily

Lara Pizzorno is the author of “Your Bones: How You Can Prevent Osteoporosis and Have Strong Bones for Life – Naturally” and a member of the American Medical Writers Association with 29 years of experience specializing in bone health.

Recently we asked Lara if she would help us provide a series of short, ongoing videos to help you (our customers and readers) stay up to date on the latest facts and science related to bone health.

In this latest video, Lara explains why you should take your calcium twice, daily, instead of taking it all at one time. Watch the video below (or read the transcript provided) and let us know what you think in the comments

Hello, I’m Lara Pizzorno. Here to try to share information with you that I hope will help you get the most out of the calcium supplements you take.

Some very interesting research has discovered that we absorb more calcium when our need is greatest and the amount consumed at one time is lower.

So the takeaway from this research which I’ll explain in a minute is that you want to take your calcium supplement in a dose of about 350 mg twice daily.

The reasons for this was dramatically shown in a study that compared the bioavailability and the absorption of calcium from calcium carbonate or calcium citrate supplements in 37 healthy men and women. Once again, as I’ve discussed in other studies, the absorption of calcium carbonate and calcium citrate was identical when these supplements were taken with a meal. As discussed, calcium carbonate requires the presence of some stomach acid so the calcium can be solubilized and best absorbed, while calcium citrate does not require this. But even a snack will provide you with enough hydrochloric acid for you to absorb as much calcium from calcium carbonate as calcium citrate. The really interesting fact revealed by this latest study is that more calcium was absorbed when a lower dose was taken at one time.

What they did with these 37 healthy men and women was they gave either a 1000 mg dose of calcium at one time or they gave 300 mg doses, twice daily. And they found that when 1000 mg was taken all at once, the subjects only absorbed 28.4% of elemental calcium from the dose. But when a 300 mg dose was given, they absorbed 36% of the calcium from that dose. And the researchers then determined that the maximum dose of elemental calcium that should be taken at one time, for the best absorption result, was 500 mg, no more than 500 mg. And that a dose of about 350 mg taken twice daily, is likely to provide the best absorption of elemental calcium from a supplement via calcium citrate or calcium carbonate.

I hope this helps you get the most out of your supplements, whichever form of calcium you choose to use. Thanks for tuning in!


Straub DA. Calcium supplementation in clinical practice: a review of forms, doses, and indications. Nutr Clin Pract. 2007 Jun;22(3):286-96. PMID: 17507729

Heaney RP, Dowell MS, Barger-Lux MJ. Absorption of calcium as the carbonate and citrate salts, with some observations on method. Osteoporos Int. 1999;9:19–23. PMID: 10367025

Author: Lara Pizzorno, MDIV, MA, LMT

Best-selling author of “Your Bones: How You Can Prevent Osteoporosis and Have Strong Bones for Life – Naturally” and a member of the American Medical Writers Association with 30+ years of experience specializing in bone health. Lara is the Editor of Longevity Medicine Review ( as well as a Senior Medical Editor for SaluGenecists Inc., and Integrative Medicine Advisors, LLC.