Dataset Information

The effect of vitamin D on calcium absorption in older women.

ABSTRACT:

Context

Vitamin D is often recommended for use with calcium supplements to increase absorption. There are no systematic studies of vitamin D on calcium absorption that indicate what dose should be recommended.

Objective

Our objective was to study the effect of increasing doses of vitamin D3 on calcium absorption.

Design and setting

We conducted a randomized double-blind placebo-controlled trial at Creighton University Medical Center, Omaha, NE.

Participants

Participants included 163 postmenopausal Caucasian women with vitamin D insufficiency, defined as a serum 25-hydroxyvitamin D (25OHD) below 20 ng/ml (50 nmol/liter).

Intervention

Participants were randomized to receive one of the vitamin D3 doses, 400, 800, 1600, 2400, 3200, 4000, or 4800 IU/d, or placebo for 1 yr. Calcium intake was increased to 1200-1400 mg daily by giving daily calcium citrate.

Main outcome

We evaluated the change in calcium absorption on vitamin D.

Results

Mean serum 25OHD increased from baseline 15.6 ng/ml (39 nmol/liter) to 46.5 ng/ml (112 nmol/liter) in subjects randomized to the highest dose of vitamin D (4800 IU). Calcium absorption was more significantly related to serum 25OHD (R2=0.50; P=0.001) than dose (R2=0.47; P=0.033). Calcium absorption of a 100-mg dose increased from 52-58% (6 mg) over a serum 25OHD range of 20-66 ng/ml (50-165 nmol/liter).

Conclusions

There was no evidence of a threshold for reduced calcium absorption in the serum 25OHD range of 10-66 ng/ml (25-165 nmol/liter). The increase in absorbed calcium of 6% on high doses of vitamin D is so small that the same amount could be obtained from half a glass of milk (100 ml) or 100 mg elemental calcium. The results challenge assumptions about the value of adding vitamin D to increase calcium absorption except when serum 25OHD is very low that is less than 10 ng/ml (25 nmol/liter).

SUBMITTER: Gallagher JC

PROVIDER: S-EPMC3462946 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND:Micronutrient deficiency affects the health and development of vulnerable population such as children and pregnant women. Measures such as fortification of food and supplementation have been implemented to prevent or control deficiencies related to micronutrients. OBJECTIVE:To assess the effect of vitamin A, vitamin D, and calcium fortification and supplementation on nutritional status of women in reproductive age group. To assess the toxicities and adverse events related to intervention. METHODOLOGY:Systematic reviews including RCTs on women of reproductive age group provided with vitamin A, vitamin D, and calcium supplementation or fortified food were included, to report all malnutrition-related outcomes due to deficiency of the abovementioned micronutrients. The Cochrane Database of Systematic Reviews, EPPI Centre, Campbell Collaboration, PubMed, Web of Science, and Scopus were searched electronically for English language publications, until 31 March 2018. Hand searching of the articles was done from the Journal of Food Science and Technology. Two independent reviewers selected the systematic reviews, extracted data, and assessed for the quality. RESULTS:A total of 16 systematic reviews were included in narrative synthesis. Supplementation of vitamin A was reported to result in increased maternal serum retinol concentrations and increased breast milk retinol concentration. It reduced the risk of anemia (Hb < 11?g/dL) and reduced maternal clinical infection. Vitamin D supplementation increased 25-hydroxy vitamin D levels. There was insufficient evidence for the effect on bone mineral density and serum calcium levels. Calcium supplementation did not have any significant effect on body weight, weight gain, and body mass index of the participants. CONCLUSION:This overview of systematic reviews reiterates the nutritional importance of vitamin A, vitamin D, and calcium supplementation for the reproductive age women. However, there was no empirical evidence available for fortification of food with vitamin A, vitamin D, and calcium and nutritional benefits of the same for reproductive age women, therefore thrusting upon the need of conducting future quality research, i.e., clinical trials and systematic reviews for food fortification. SYSTEMATIC REVIEW REGISTRATION:A priori protocol for this overview of systematic reviews was registered in PROSPERO with registration number CRD42018089403 .