Vitamin D supplementation in nursing mothers and infants

Who benefits most-or at all-from vitamin D supplementation? Such was the basis of the discussion “Vitamin D supplementation: Breastfeeding mothers, breastfed babies, both, or neither?” at the American Academy of Pediatrics (AAP) 2017 National Conference and Exhibition on September 16.

Debra Bogen, MD, FAAP, FABM, professor of Pediatrics, Psychiatry, and Clinical and Translational Sciences at the University of Pittsburgh School of Medicine, Pennsylvania, presented a case study of a breastfed infant with rickets followed by data on vitamin D levels and supplementation for women and infants.

Vitamin D plays an important role in bone health, calcium metabolism, and immune modulation, says Bogen. Although vitamin D insufficiency and deficiency have been implicated in many other health disorders, she says evidence to support these claims are mixed.

“Because infants and toddlers are growing rapidly, maintaining an appropriate vitamin D level is essential. Infants and toddlers who do not get enough vitamin D develop rickets and osteomalacia,” says Bogen.

The 2 main sources of vitamin D are through sunlight exposure or diet. There are challenges, however, to defining normal or healthy levels of vitamin D, Bogen says. There is even disagreement on how to measure vitamin D levels. She says even the Institute of Medicine (IOM) and the Endocrine Society differ on these definitions and measurements, with the IOM defining deficiency at less than 12 ng/mL and other experts including the Endocrine Society defining deficiency at less than 20 ng/mL.

These same problems with definition exist in pregnancy, too, although Bogen says most experts agree that a serum level of 25(OH)D of 20 ng/mL or more is needed to avoid bone problems.

Optimal serum levels during pregnancy, however, remain unknown, Bogen says, and is an area of active clinical research. Based on the limited research to date, recommendations for vitamin D supplementation in pregnancy are unclear, she adds.

The American Congress of Obstetricians and Gynecologists (ACOG) agrees, stating there is currently insufficient evidence to support routine screening for vitamin D deficiency in pregnant women, but ACOG acknowledges that severe deficiency can result in skeletal homeostasis, congenital rickets, and fractures in newborns, according to Bogen’s presentation. Screening is recommended for certain high-risk groups including vegetarians, pregnant mothers with limited sun exposure, and darker skinned ethnic minorities.

For infants and toddlers, the recommendations are more clear, Bogen says. At least 400 IU per day of vitamin D is recommended. Breastfed and partially breastfed infants should receive this through supplementation of 400 IU per day of vitamin D beginning in the first few days of life, she says. Supplementation should continue until infants are weaned to at least 1 liter of vitamin-D fortified milk per day-with the warning that no infants should be given whole milk before 12 months of age.

Current evidence indicates that serum 25(OH)D should be 20 ng/mL in infants and children, according to Bogen’s presentation. For infants who are bottle-fed or for older children who consume 1 liter or more of vitamin-D fortified formula or milk per day, 400 IU per day of supplementation, or additional dietary sources including vitamin-fortified cereals, is recommended.

“Breastfed infants are at high risk for vitamin D deficiency because they do not get much sunlight and breastmilk has limited amount of vitamin D unless women have high levels of vitamin D themselves,” Bogen says.” Like vitamin D fortified cow’s milk, vitamin D is added to breastmilk substitutes (formulas). Infants who drink at least 1 liter of formula get adequate amounts of vitamin D to prevent rickets and osteomalacia.”

The question, therefore, is whether to recommend vitamin D supplementation for breastfeeding mothers, their breastfed infants, or both. In her presentation, Bogen discussed a study that supports the safety and efficacy of women taking high doses of vitamin D (6400 IU per day) to increase the levels of vitamin D in their milk and for their infants, but this is not currently recommended by the AAP, Bogen notes. Current AAP recommendations support supplementation for infants, and continued prenatal vitamins and possible vitamin B supplementation for nursing mothers. The full recommendation can be found here.