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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #315589

Research Project: Pediatric Clinical Nutrition

Location: Children's Nutrition Research Center

Title: Bioavailability of enteric-coated microencapsulated calcium during pregnancy: A randomized crossover trial in Bangladesh

Author
item Roth, Daniel - Hospital For Sick Children (SICKKIDS)
item Pezzack, Brendon - Hospital For Sick Children (SICKKIDS)
item Mahmud, Abdullah Al - International Centre For Diarrhoeal Disease Research
item Abrams, Steven - Children'S Nutrition Research Center (CNRC)
item Islam, Munirul - International Centre For Diarrhoeal Disease Research
item Aimone Phillips, Ashley - Hospital For Sick Children (SICKKIDS)
item Baxter, Jo-anna - Hospital For Sick Children (SICKKIDS)
item Dimitris, Michelle - Hospital For Sick Children (SICKKIDS)
item Hawthorne, Keli - Children'S Nutrition Research Center (CNRC)
item Ahmed, Tahmeed - International Centre For Diarrhoeal Disease Research
item Zlotkin, Stanley - Hospital For Sick Children (SICKKIDS)

Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2014
Publication Date: 10/1/2014
Citation: Roth, D.E., Pezzack, B., Mahmud, A., Abrams, S.A., Islam, M., Aimone Phillips, A., Baxter, J.B., Dimitris, M.C., Hawthorne, K.M., Ahmed, T., Zlotkin, S.H. 2014. Bioavailability of enteric-coated microencapsulated calcium during pregnancy: A randomized crossover trial in Bangladesh. American Journal of Clinical Nutrition. 100(6):1587-1595.

Interpretive Summary: Prenatal calcium and iron supplements are recommended in settings of low dietary calcium intake and anemia. However, calcium administration may inhibit iron absorption. We studied a multi-micronutrient powder containing iron and calcium carbonate granules in a capsule to help slow down the way it is released in the intestine and perhaps make it get absorbed better. This study was a trial conducted in pregnant women in Bangladesh. Calcium absorption was measured at different intake levels using non-radioactive stable isotopes of iron. We found that the calcium absorption was low in the encapsulated granules. Therefore, in its current formulation, this novel supplement is not suitable for clinical use. Calcium absorption depended on how much was given, such that 1000 mg and 1500 mg supplements of calcium did not actually provide much more calcium to the body than 500 mg supplements. Other methods of supplementation should be explored.

Technical Abstract: Prenatal calcium and iron supplements are recommended in settings of low dietary calcium intake and high prevalence of anemia. However, calcium administration may inhibit iron absorption. To overcome calcium-iron interactions, we developed a multi-micronutrient powder containing iron (60 mg), folic acid (400 ug), and calcium carbonate granules microencapsulated with a pH-sensitive enteric coating to delay intestinal release. We aimed to establish in vivo evidence that enteric-coated (EC) calcium is bioavailable in pregnant women and to explore the dose responsiveness of fractional calcium absorption (FCA) in pregnancy. This was a randomized crossover trial in pregnant women (26–28 wk of gestation) in Dhaka, Bangladesh. Participants were allocated to 1 of 3 dose groups (500, 1000, or 1500 mg elemental Ca). FCA was estimated in random order for EC and non-EC (control) granules by a dual-stable-isotope method (44Ca-labeled granules and intravenous 42Ca) on the basis of the relative recovery of 44Ca compared with 42Ca in urine over 48 h. Forty-nine participants with FCA for both EC and non-EC granules were included in the primary analyses. FCA geometric means were as follows: 21.8% (500 mg), 9.2% (1000 mg), and 11.7% (1500 mg) for non-EC granules compared with 3.3% (500 mg), 1.2% (1000 mg), and 2.1% for EC granules. Cumulative 48-h FCA of EC calcium was 85% lower (P < 0.001) than that of non-EC calcium, after adjustment for dose. In comparison to 500 mg, the FCA for the 1000-mg dose was 61% lower (P < 0.001) and was 42% lower (P = 0.002) for the 1500-mg dose, after adjustment for formulation. A pH-sensitive enteric coating substantially reduced calcium absorption from a prenatal multi-micronutrient powder. In its current formulation, this novel supplement is not suitable for clinical use. FCA was highly dose-dependent, such that doses of 1000 and 1500 mg delivered only negligibly more bioavailable calcium than the 500-mg dose.