Breast Milk: It Does Not Contain Enough Vitamin D3

Although considered a "perfect" food, breast milk does not contain sufficient amounts of vitamin D. For this reason, exclusively breastfed infants are at risk of deficiency, especially if they are not adequately exposed to sunlight. A new study reveals that taking doses of vitamin D much higher than the recommended amounts during the breastfeeding period allows new mothers to avoid the risk of deficiency and provides a valid alternative to direct supplementation of the infant.

This is stated by a study conducted by researchers at the Medical University of South Carolina (USA) and published in the journal Pediatrics.

Breast Milk Does Not Contain Enough Vitamin D

Colostrum, the milk produced during the first days of lactation, is particularly rich in nutrients necessary for the newborn. The nutritional content of breast milk then continues to change during the course of breastfeeding and is highly variable from woman to woman. Although considered a "perfect" food, breast milk does not contain sufficient quantities of vitamin D to maintain in infants the proper level of 25-hydroxy-vitamin D, an intermediate of the biologically active form.

For this reason, exclusively breastfed infants are at risk of deficiency, especially if they are not exposed to the sun, which, as is well known, stimulates the production of vitamin D in the skin from a precursor molecule. It also appears that children belonging to certain ethnicities with darker skin are particularly prone to this deficiency.

Vitamin D is valuable for bone health and therefore essential to prevent rickets, and it is critical for the proper development of the child's skeleton. To fully meet infants’ vitamin D needs, supplements can be administered directly to the newborn or maternal supplementation can be used to increase the vitamin D content in breast milk.

Supplementation with 6400 IU of Vitamin D Prevents Deficiency in Breast Milk

During the study, researchers compared the effectiveness of maternal supplementation with 160 micrograms per day to maternal and infant supplementation with much lower doses of vitamin D. The data showed that the higher amount is able to ensure, during breastfeeding, the optimal amount of vitamin D for the infant.

In detail, the analyses showed that mothers who had received 400 International Units (IU) of vitamin D, equivalent to 10 micrograms, or 2400 IU (60 micrograms), were more likely to have a vitamin D deficiency than those who had received 6400 IU, an amount equal to 160 micrograms. Moreover, during breastfeeding, blood concentrations of 25-hydroxy-vitamin D decreased in women who received 400 IU, while they increased in the group of mothers who took the higher dose.

After the first month of life, more than 70% of the babies had vitamin D concentrations below the recommended level (50 nanomoles per liter). One of the most important results was observing that the vitamin D concentrations in the blood were similar between breastfed infants whose mothers consumed 6400 IU of vitamin D daily and those who received 400 IU directly orally.

Key Points of the Research

The women involved in this study, 334 paired with their babies, were selected from two distinct latitudes in America with strong ethnic diversity so that the results can be generalized to a wide variety of mothers. Furthermore, the doses of vitamin D used in this study caused no side effects and are considered safe by the authors of the research, as no adverse effects are known.

Regarding this, the Institute of Medicine (IOM), the academic association that provides health advice and opinions, has increased the limit to 4000 IU per day, and the Endocrine Society (an international hormone research society) has set the upper limit at 10,000 IU per day.

Mothers Should Take More Vitamin D

This study highlights how the amounts of vitamin D taken by mothers and exposure to sunlight are often insufficient, and consequently, the composition of breast milk may not guarantee an optimal amount for infants.

Just as happens with omega-3: low consumption of fatty fish during pregnancy can cause a deficiency in human milk of important fatty acids for the child's development. Adequate vitamin D intake and supplementation can therefore ensure breastfeeding women have optimal vitamin levels in milk and thus in their babies. To stay updated on the latest news from scientific research on Omega-3, subscribe to our newsletter.

Sources: Hollis BW, Wagner CL, Howard CR, Ebeling M, Shary JR, Smith PG, Taylor SN, Morella K, Lawrence RA, Hulsey TC. Maternal vs infant vitamin D supplementation during lactation: A randomized controlled trial. 2015 Pediatrics. Luzwolda MF, Kuipers RS, Koops J-H, Muller S, de Graaf D, Dijck-Brouwer DAJ, Muskiet FAJ. Interrelationships between maternal DHA in erythrocytes, milk and adipose tissue. Is 1 wt% DHA the optimal human milk content? Data from four Tanzanian tribes differing in lifetime stable intakes of fish. 2013 Br J Nutr.