Children's Nutrition

Breast-Feeding and Vitamin D

RDs who work in pediatrics or with breast-feeding moms receive lots of questions about vitamin D supplementation and their babies. Moms want to know, “If breastmilk is perfect for my baby, why do they need vitamin D?”

Why Does Vitamin D Matter?
As dietitians, we know the essential functions of vitamin D and how deficiency has been linked to multiple health conditions. The health issues related to vitamin D affect not only adults but infants and children, too. Although it’s rare, rickets is a disease that causes the softening or weakening of the bones of children and, in most cases, is caused by vitamin D deficiency.

Does Vitamin D Pass Through Breastmilk?
A common misconception, and what many breast-feeding mothers are told, is that vitamin D doesn’t pass through breastmilk. In reality, the amount that passes through breastmilk depends on the mother’s intake and stores. Many women in the United States, especially in the northern regions of the country, are vitamin D deficient; therefore, so is their breastmilk.

Risk Factors
Dietitians should be able to educate their clients on the risk factors for deficiency, which include the following:

  • inadequate sun exposure;
  • darker skin color;
  • medical conditions that affect nutrient absorption;
  • obesity; and
  • restricted or inadequate diet.

Sources of Vitamin D
RDs can encourage breast-feeding women to get vitamin D from these three sources:

1. Sunshine: One form of vitamin D that the body synthesizes is found on our skin. However, this form remains inactive until it comes into contact with UV rays. Most research suggests that just 10 minutes of direct exposure (ie, no sunscreen, no clothing) during prime hours of sunlight (10 AM to 2 PM) is enough to provide adequate amounts.

2. Food: Though food is likely where most people get their vitamin D, there aren’t many sources. Not to mention the food sources that do exist aren’t commonly consumed. Vitamin D is found in fortified dairy, fatty fish such as salmon and sardines, egg yolk from pasture-raised chickens, UV-exposed mushrooms, and fortified foods.

3. Supplements: Vitamin D is found in many multivitamins or alone in either pill or liquid form.

Vitamin D Supplementation During Breast-Feeding
The current practice is for all breast-fed babies to be supplemented 400 IU of vitamin D daily. However, a 2015 study suggested that supplementing babies with vitamin D wasn’t filling nutrition gaps and that previous studies had shown a compliance rate of less than 20%. In these studies, the mothers stated that giving their breast-fed baby a supplement was messy and cumbersome. Many admitted they often just forgot.

What the study ultimately concluded was that supplementing the breast-feeding mother with 6,400 IU of vitamin D every day was enough to supply sufficient amounts in her breastmilk and could be an alternate strategy to supplementing the baby. The caveat here is that this level of supplementation assumes mom’s vitamin D level is optimal to begin with. If mom is deficient, 6,400 IU may not be enough. When dietitians are counseling breast-feeding moms or seeing a breast-fed baby, it’s important to know the different options for vitamin D supplementation to help them determine which option is best for each mother-baby pair.

Bottom Line
Vitamin D is present in breastmilk, but because it’s “dose dependent” and most breast-feeding moms are deficient, it’s likely that the amounts passed to baby are insufficient. Now, moms have the option to supplement themselves instead of their babies. RDs working with breast-feeding moms should be able to educate them on the importance of vitamin D and all of their options for supplementation.

— Meghan McMillin, MS, RDN, CSP, LDN, IBCLC, is a private practice dietitian and lactation consultant, freelance writer, and professional speaker who strives to empower women with the tools and information they need to nourish themselves and their babies. Meghan’s areas of expertise include breast-feeding and food allergies, baby-led weaning, and postpartum nutrition. You can find Meghan blogging on her website Mama & Sweet Pea Nutrition or on Instagram @the.lactation.dietitian.

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