From Medscape Medical News

US Infants May Have Inadequate Vitamin D Status

Laurie Barclay, MD

Authors and Disclosures

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March 24, 2010 — US infants may have inadequate vitamin D status, according to the results of 2 studies reported in the April issue of Pediatrics.

One study suggests that most US infants are consuming inadequate amounts of vitamin D, based on the 2008 recommendation of the American Academy of Pediatrics (AAP), and a second study showed vitamin D deficiency in a high proportion of infants and their mothers in Boston, Massachusetts.

"There have been few data on the prevalence of US infants meeting AAP vitamin D recommendations," write Cria G. Perrine, PhD, from the Centers for Disease Control and Prevention in Atlanta, Georgia, and colleagues. "In November 2008, the [AAP] doubled the recommended daily intake of vitamin D for infants and children, from 200 IU/day (2003 recommendation) to 400 IU/day. We aimed to assess the prevalence of infants meeting the AAP recommended intake of vitamin D during their first year of life."

The investigators estimated the percentage of infants (n = 1952 - 1633) meeting current AAP vitamin D recommendations at ages 1, 2, 3, 4, 5, 6, 7.5, 9, and 10.5 months, based on data from the Infant Feeding Practices Study II, performed from 2005 to 2007.

Regardless of whether infants were fed breast milk or formula, the use of oral vitamin D supplements was low, ranging from 1% to 13%, and varied by age. Only 5% to 13% of infants fed breast milk but no formula met either the 2003 or the 2008 AAP recommendation. The 2003 recommendation was met by 28% to 35% of mixed-fed infants, but only 9% to 14% would have met the 2008 recommendation. For infants fed formula but not breast milk, 81% to 98% met the 2003 recommendation, but only 20% to 37% would have met the 2008 recommendation.

"Our findings suggest that most US infants are not consuming adequate amounts of vitamin D according to the 2008 AAP recommendation," the study authors write. "Pediatricians and health care providers should encourage parents of infants who are either breastfed or consuming <1>

Limitations of this study include self-reported data subject to recall bias and a lack of generalizability to the national population because the study sample had higher educational levels, fewer children, and longer duration of breastfeeding. In addition, the investigators could not determine the exact quantity of vitamin D that infants obtained from oral supplements.

"Pediatricians and other health care providers can support and promote daily oral vitamin D supplementation of infants by explaining to parents the purpose and benefits of vitamin D supplementation, reminding parents at each visit to give vitamin D supplements to their children, suggesting that parents develop a daily intake routine to help them remember to administer the supplement, asking parents about any adverse effects of supplementation or barriers to giving their infants supplements, and helping parents to overcome any barriers that they report," the study authors conclude.

The goal of the second study, by Anne Merewood, MPH, IBCLC, from Boston Medical Center, and colleagues, was to assess vitamin D status and related factors in a cohort of 459 healthy newborns and their mothers in Boston.

This cross-sectional study was performed from 2005 to 2007 in an urban Boston teaching hospital with 2500 births per year, using a questionnaire and medical-record data to examine factors that may be associated with vitamin D deficiency. Within 72 hours of birth, infant and maternal blood were obtained by venipuncture for measurement of 25-hydroxyvitamin D [25(OH)D] status, assessed by competitive protein binding.

In analyses on 376 newborns and 433 women, the median infant 25(OH)D level was 17.2 ng/mL (95% confidence interval [CI], 16.0 - 18.8 ng/mL; range, <5.0>

Factors associated with increased risk for infant vitamin D deficiency were maternal deficiency (adjusted odds ratio [aOR], 5.28; 95% CI, 2.90 - 9.62), winter birth (aOR, 3.86; 95% CI, 1.74 - 8.55), black race (aOR, 3.36; 95% CI, 1.37 - 8.25), and maternal body mass index of 35 kg/m² or higher (aOR, 2.78; 95% CI, 1.18 - 6.55).

Maternal prenatal vitamin use throughout the second and third trimesters was associated with lower risk for infant deficiency (aOR, 0.30; 95% CI, 0.16 - 0.56), and prenatal vitamin use of 5 or more times per week in the third trimester was associated with lower risk for maternal deficiency (aOR, 0.37; 95% CI, 0.20 - 0.69). Nonetheless, more than 30% of women who took prenatal vitamins were still vitamin D deficient at the time of delivery.

Study limitations include retrospective data collection and that baseline values of 25(OH)D missing for some infants.

"A high proportion of infants and their mothers in New England were vitamin D deficient," the study authors write. "Prenatal vitamins may not contain enough vitamin D to ensure replete status at the time of birth."

The Centers for Disease Control and Prevention study was supported by the US Food and Drug Administration, Centers for Disease Control and Prevention, Office of Women's Health, National Institutes of Health, and Maternal and Child Health Bureau in the US Department of Health and Human Services. The Boston study was supported by grants from Health Resources and Services Administration/Bureau of Maternal and Child Health; US Department of Agriculture/Cooperative State Research, Education, and Extension Service; and General Clinical Research Centers Program of the National Center for Research Resources, National Institutes of Health. The study authors have disclosed no relevant financial relationships.

Pediatrics. 2010;125:627-632, 640-647.