Healthy Science/ Why is Vitamin D Important for Infants?

Why is Vitamin D Important for Infants?

  • In addition to its well-known benefits for bone and muscle health, vitamin D can help regulate babies’ immune and respiratory function
  • Risk factors for vitamin D deficiency in infants include limited sun exposure, low maternal vitamin D levels during pregnancy, and breastfeeding
  • Experts recommend that infants receive vitamin D supplementation beginning shortly after birth

Vitamin D deficiency is highly prevalent amongst infants, and estimated to affect between 2.7% to 45% of infants worldwide.15 Many factors contribute to the incidence of vitamin D deficiency, including limited sun exposure, dietary intake, where an individual lives, seasonal variation, darker skin pigmentation, and more.1618

Vitamin D helps to maintain healthy bone density in infants and toddlers

Vitamin D supports the formation and mineralization of healthy bones and muscle function by helping maintain a healthy balance of the minerals calcium, phosphorus, sodium, and magnesium within the body.1 The significance of vitamin D for musculoskeletal health is evidenced by rickets, a serious condition affecting bone integrity caused by severe vitamin D deficiency. The incidence of this debilitating condition peaks between 3 to 18 months of age, and is characterized by low bone density, bone deformities, weak and toneless muscles, and growth impairment.2,3 Without timely and sufficient vitamin D treatment, this condition can have lifelong consequences.

The role of vitamin D in building and maintaining bone density in children is also indicated by the prevalence of fractures, or bone breaks. It is estimated that fractures account for up to 12% of pediatric injuries.4,5 Fortunately, vitamin D from the diet or supplementation decreases the risk of fracture, while promoting healthy motor development in infants and toddlers.6,7

Vitamin D supplementation can help support respiratory health in infants

In addition to musculoskeletal difficulties, insufficient vitamin D can also affect an infant’s developing immune system, placing them at a heightened risk of respiratory complications, flu, and allergies.8 Particularly concerning for infants, research shows that low levels of vitamin D are associated with respiratory tract issues that can potentially lead to chronic complications throughout life.911

However, research also suggests that vitamin D supplementation can help support respiratory health. For example, supplementing infants with vitamin D has been found to help reduce wheezing and promote normal, healthy respiratory tract functions.1214 Supplementation has also been found to limit the incidence of common allergies, such as eggs and peanuts.1214

Risk Factors for Vitamin D Deficiency in Infants:

Risk Factor #1: Low maternal vitamin D levels during pregnancy 

An infant’s level of vitamin D is initially influenced by their mother’s vitamin D status during pregnancy. If the mother’s level is low, this can increase the infant’s risk of vitamin D deficiency at birth, putting them at a heightened risk for preterm birth, low birth weight, and decreased bone mineralization.19 Research indicates that long-term bone development and respiratory health may also be impacted.20

Receiving adequate amounts of vitamin D during pregnancy can help ensure that infants are born with sufficient levels of vitamin D.19 Link to The Importance of Vitamin D during Pregnancy for more information. However, for various reasons, supplementation during pregnancy often does not occur. If this is the case, rest assured that infants can obtain sufficient vitamin D levels through supplementation after birth.21

Risk Factor #2: No direct sun exposure

Exposure of the skin to UVB rays from sunlight can provide adequate amounts of vitamin D, see link to An Introduction to Vitamin D. However, to protect an infant from UV radiation damage, the American Academy of Pediatrics guidelines advise parents to keep infants younger than 6 months of age out of direct sunlight.22 Although these guidelines provide important safety precautions, they prevent younger infants from being exposed to a potent driver of vitamin D synthesis. As a result, this increases an infant’s risk of vitamin D deficiency. 

Pediatricians recommend that parents begin supplementing their infants with vitamin D in the first few days of life, which can successfully increase babies vitamin D levels.19 Supplementation in the absence of direct sun exposure can positively impact infants’ vitamin D levels, and influence their health for years to come.

Risk Factor #3: Breastfeeding 

With sufficient maternal nutrition, breastmilk naturally provides infants younger than 6 months with a complete source of nutrition. Although it is generally agreed that breastmilk is the best food source for infants, because mothers typically do not have exceptionally high vitamin D levels, breastmilk alone does not provide infants with sufficient amounts of vitamin D.19,22 As a result, exclusive breastfeeding can increase an infant’s risk of vitamin D deficiency. 

In addition to supplementing breastfeeding infants with vitamin D shortly after birth, another way to support their vitamin D status is through maternal supplementation. While the amount of vitamin D a woman needs to provide adequate levels to her infant through breastmilk has yet to be established, some researchers report that lactating moms would need to take as much as 6400 IU/day.23 However, in the absence of formal recommendations for breastfeeding moms, infant supplementation is highly recommended.

Frequently Asked Questions on Vitamin D Supplementation for Infants

Given vitamin D’s important benefits for infants’ musculoskeletal, respiratory, and immune health, supplementation is generally recommended by pediatricians during infancy. Below are answers to frequently asked questions regarding vitamin D supplementation for infants. Since proper care and precautions should always be taken when providing infants with supplements, this information is best utilized as a guide for discussing supplementation with your child’s pediatrician.   

How much vitamin D should my breastfed baby take?

Because most women do not consume high amounts of vitamin D, the levels found in breast milk typically do not provide a sufficient amount for infants.24 For this reason, the American Academy of Pediatrics recommends that infants who are exclusively breastfed receive supplementation with 400 IU of vitamin D daily.2,25

However, research suggests that 400 IU/day might not be enough for all infants.26,27 For example, a study comparing the vitamin D levels of infants supplemented with either 400, 800, 1200, or 1600 IU/day of vitamin D found that after 3 months, only 55% of the infants receiving 400 IU/day had sufficient vitamin D levels (> 30 ng/mL or 75 nmol/L). This is in comparison to 81%, 92%, and 100% of the infants from the 800, 1200, and 1600 IU/day groups, respectively.26 To find the right dose for your infant, talk with your pediatrician about testing options.

Can maternal vitamin D supplementation while breastfeeding provide an infant with enough vitamin D?

In short, the answer is maybe. If a breastfeeding mother were to supplement with a high dose of vitamin D, she could potentially transfer sufficient levels to an exclusively breastfed infant.28 However, in the absence of a medical consensus regarding how much vitamin D a mother would need to take to provide sufficient vitamin D through breastmilk, all we can say is that she would require more than the standard recommendation of 600 IU/day, which many scientists agree is not enough.23,29,30

How much more? Below we provide research findings from studies looking at maternal supplementation relative to levels of vitamin D found in breastmilk. 

  • Researchers reported that maternal supplementation of 6,400 IU/day during breastfeeding (without infant supplementation) resulted in infants with similar vitamin D levels to those with infant supplementation of 400 IU/day of vitamin D.23
  • Another study showed that 5,000 IU/day or a one-time dose 150,000 IU of maternal supplementation for 28 days provided infants adequate amounts of vitamin D from breastmilk.31
  • A popular clinical resource text, Hale’s Medications and Mother’s Milk, recommends 4000 IU/day of vitamin D, based on evidence from clinical trials.32

How much vitamin D should my formula-fed baby take?

Infants who are fed formula exclusively receive an estimated 324 – 520 IU/day of vitamin D. However, these values will vary according to how much formula the baby actually consumes, so supplementation may be advised for them as well.25 More specifically, the American Academy of Pediatrics recommends vitamin D supplementation for formula-fed infants receiving less than 1L of formula per day (»400 IU of vitamin D).22

How much is too much vitamin D for my infant?

While many caregivers fret over accidently giving their infant an extra drop of vitamin D, research suggests that the risk of taking too much vitamin D is actually quite low.  As discussed earlier in this article, doses as high as 1600 IU/day have safely been used with infants.26 The Clinical Practice Guidelines states that up to 2,000 IU is safe for infants (0 – 1 year of age) and up to 4,000 IU is safe for toddlers (1-3 years of age).33 Importantly, these guidelines are based on evidence from clinical studies demonstrating that these amounts are safe, and report no signs of vitamin D toxicity.16

Experts recommend that infants receive vitamin D supplementation

Vitamin D is extremely important for an infant’s musculoskeletal, immune and respiratory health. Low levels of maternal vitamin D during gestation, no direct sun exposure, and exclusive breastfeeding are common risk factors for vitamin D deficiency in infants. Given that vitamin D deficiency can have negative implications for lifelong health and wellness, it is strongly recommended that exclusively breast-fed infants and formula-fed infants consuming less than 1L formula/day begin supplementation shortly after birth. Always discuss your infant’s unique dietary and supplemental needs you’re your pediatrician. To learn more check out, An Introduction to Vitamin D.

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