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New study finds no evidence for a threshold of calcium absorption in response to vitamin D supplementation

Posted on: May 9, 2014   by  Will Hunter


A randomized placebo-controlled trial published in The American Journal of Clinical Nutrition has found that there is no threshold for vitamin D levels beyond which calcium absorption is unaffected.

It has been proposed that there exists a point, or a threshold, at which any increase in serum vitamin D levels will have no effect on the amount of calcium absorbed by an individual.

If this threshold does exist, it would act as a biomarker to determine vitamin D sufficiency. Researchers reason that once maximal absorption of calcium has been reached, there is no rationale for continuing to increase vitamin D levels to support skeletal health.

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2 Responses to New study finds no evidence for a threshold of calcium absorption in response to vitamin D supplementation

  1. speedmango

    While somewhat useful, this study is too short to provide confidence in the assertion. These 76 women never achieved a vitamin d level in the normal range. A six month study would have been much more helpful. and may well. It’s also not mentioned what kind of diet this population enjoyed. This is better, but still sloppy science.

    • Will Hunter


      I agree with you. Eight weeks is simply not enough time to rule out the existence of a threshold. Although there was random assignment, the researchers should have somehow monitored dietary calcium to make sure there wasn’t a significant difference in the two groups.


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