A Closer look at calcium absorption and the benefits and risks of dietary versus supplemental calcium

Postgrad Med. 2013 Nov;125(6):73-81. doi: 10.3810/pgm.2013.11.2714.


Objective: To perform a thorough search of the literature on calcium research and specifically address the topic of calcium absorption.

Methods: PubMed and Ovid were the main engines used for primary literature searches; textbooks, review articles, and book chapters are examples of the other sources used for supplemental information.

Results: Regarding calcium absorption, it seems apparent that the absorption efficiency of all calcium salts, regardless of solubility, is fairly equivalent and not significantly less than the absorption efficiency of dietary calcium. However, dietary calcium has been shown to have greater impact in bone building than supplemental calcium. This is likely due to improved absorption with meals and the tendency of people to intake smaller amounts more frequently, which is more ideal for the body's method of absorption. In addition, the cardiovascular risks of excessive calcium intake appear to be more closely related to calcium supplements than dietary calcium; this relationship continues to be controversial in the literature.

Conclusions: We conclude that further studies are needed for direct comparison of supplemental and dietary calcium to fully establish if one is superior to the other with regard to improving bone density. We also propose further studies on the cardiovascular risk of long-term increased calcium intake and on physician estimates of patients' daily calcium intake to better pinpoint those patients who require calcium supplementation.

Publication types

  • Review

MeSH terms

  • Age Factors
  • Bone Density / physiology
  • Bone and Bones / physiology*
  • Calcium / administration & dosage
  • Calcium / adverse effects
  • Calcium / pharmacokinetics*
  • Calcium, Dietary / administration & dosage
  • Calcium, Dietary / adverse effects
  • Calcium, Dietary / pharmacokinetics*
  • Dietary Supplements*
  • Humans
  • Intestinal Absorption
  • Osteoporosis / prevention & control
  • Sex Factors


  • Calcium, Dietary
  • Calcium