Optimal Vitamin D Dosage for Infants Uncertain

In a comparison of the effect of different dosages of vitamin D supplementation in breastfed infants, no dosage raised and maintained plasma concentrations within a range recommended by some pediatric societies. However, all dosages raised and maintained plasma concentrations within a lower range recommended by the Institute of Medicine, according to a study in The Journal of the American Medical Association.

Hope Weiler, RD, PhD, of McGill University, Montreal, presented the findings at a Journal of the American Medical Association media briefing.

“Vitamin D is important during periods of rapid bone mineral accrual. Nursing infants are susceptible to vitamin D deficiency because vitamin D in breast milk is limited,” according to background information in the article. “A supplement of 400 IU of vitamin D per day is thought to support plasma 25-hydroxyvitamin D (25[OH]D) concentrations between 40 and 50 nmol/L; some advocate 75 to 150 nmol/L for bone health. … the lack of well-defined recommendations supports the need for dose-response studies.”

Weiler and colleagues conducted a study to investigate the efficacy of different dosages of oral vitamin D in supporting 25(OH)D concentrations in infants. The randomized clinical trial, which included 132 one-month-old healthy, term, breastfed infants, was conducted between March 2007 and August 2010. Infants were followed up for 11 months ending August 2011 (74% completed the study). Participants were randomly assigned to receive oral cholecalciferol (vitamin D3) supplements of 400 IU/d (n=39), 800 IU/d (n=39), 1,200 IU/d (n=38), or 1,600 IU/d (n=16).

The researchers found that the percentage of infants achieving the primary outcome of 75 nmol/L of 25(OH)D differed at 3 months by group (for 400 IU/d, 55%; for 800 IU/d, 81%; for 1,200 IU/d, 92%; and for 1,600 IU/d, 100%). “This concentration was not sustained in 97.5% of infants at 12 months in any of the groups. The 1,600-IU/d dosage was discontinued prematurely because of elevated plasma 25(OH)D concentrations.”

Overall, 97% of infants in all treatment groups achieved the secondary outcome of 50 nmol/L or greater of plasma 25(OH)D by 3 months of age, with no differences among groups. This concentration was sustained in 98% of infants at 12 months.

Bone mineral concentration increased over time for lumbar spine, femur, and whole body but did not differ by group.

“Our primary objective was to establish a vitamin D dosage that would support a plasma concentration of 25(OH)D of 75 nmol/L or greater in 97.5% of infants at 3 months of age. Only the 1,600-IU/d dosage of vitamin D met this criterion; however, this dosage was discontinued because most infants in that group developed elevated plasma 25(OH)D concentrations that have been associated with hypercalcemia [higher-than-normal level of calcium in the blood],” the authors wrote. “Thus, the primary outcome was not achieved at 3 months, when plasma 25(OH)D concentrations were highest; all dosages failed except the highest dosage, which appears to be too high.”

“Additional studies are required before conclusions can be made regarding higher targets or the needs of high-risk groups.”

Source: American Medical Association

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