In individuals who are vitamin D deficient, only 10-15% of the calcium that they ingest is absorbed; and the better your vitamin D status – remember optimal blood levels of 25OHD which is the circulating form of vitamin D in the blood stream, the form that is used to monitor vitamin D status.Optimal blood levels of 25OHD are 60 -80 nano grams per mL. So when you’re in that range, you’ll be able to absorb the best amount of calcium from what you ingest. In one study that was done, calcium absorption rates were 65% greater in individuals whose 25OHD levels in their blood were at least 34.6 nano grams per mL. And those who had levels of vitamin D circulating in their blood less than 20 nano grams per mL were only able to absorb less than half that amount of calcium. In another study of 23 vitamin D sufficient, postmenopausal women, they looked at how well the women were able to absorb calcium carbonate and calcium citrate in supplements. and what they found is that if they had adequate vitamin D, the women were both able to absorb calcium carbonate and calcium citrate in the same amount. But if they didn’t have enough vitamin D they were not able to absorb as much calcium and their parathyroid level hormones went up and they excreted more calcium in their urine when they did not have adequate vitamin D. But they found in the people that did have adequate vitamin D, the bioavailability of calcium carbonate and calcium citrate was identical. The cost of calcium carbonate was much less and people had to take much fewer pills of calcium carbonate. So the researchers recommended calcium carbonate for people with adequate vitamin D stores. There are some other considerations that will help you make the most of the calcium you consume in the form of food or supplements and we’ll talk about those more in the next video. Thanks for tuning in!
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