Vitamin D in breastmilk

Breastmilk contains all the nutrients a healthy, full-term baby needs during about the first six months of life. In the second half of the first year, other foods than breastmilk are slowly introduced. This time is a learning period for babies who should learn to master how to put food in their mouth, chew and swallow. Breastmilk is still the staple food at this time.

Recently, the American Academy of Pediatricians (AAP) released a report recommending supplementation of vitamin D for all breastfed infants in the US. Does this mean that breastmilk does no longer provide all the vitamins and minerals a baby needs? Absolutely not! In the following sections, this will be explained.

Where does the vitamin D come from?

In fact, vitamin D is not a vitamin, but a hormone. The precursor of this substance can be converted to what we call vitamin D. This happens in the skin under the influence of UVB radiation in sunlight. This is the natural way most human beings get sufficient vitamin D. Researchers estimated that daily exposure of small parts of the skin of European infants during 10 minutes may be sufficient to prevent deficiencies. Other sources may be fatty fish, fortified margarine and milk, eggs, butter. Besides sunlight, food is also considered a source of vitamin D. A mother with adequate nutrition gives her infant about roughly two months worth of vitamin D stores during pregnancy that carries to term. After that, in one way or the other a child should get vitamin D.
Breastmilk does contain vitamin D in the range of 5 to 136 IU per liter. Infants should get about 200 to 400 IU per day. If exposure to sunlight can provide the additional needed vitamin D, then what is the problem?

Breastmilk and sunexposure

Let's assume that the amount of vitamin D in breastmilk did not change over the centuries. Still, there appears nowadays to be a larger risk in infants to be deficient. Reasons for this deficiency may be:
Not living at the latitude that fits your skin color. People with a light skin at lower latitudes are likely to either avoid sun exposure to prevent sunburn, or use sunscreen, which protects against the effects of UVB, including production of vitamin D in the skin. People with a darker skin living at higher latitudes may not get the right amount of sun exposure, since their skin protects them against the effects of UVB radiation. In the winter, this effect is even stronger.
Sun exposure can further be inadequate as a result of clothing (to protect from cold, sun light or as a cultural norm), living indoors during daytime (including at daycare centers) and weather conditions.

So over all, the amount of sunexposure changed and so did the production of vitamin D in the skin. The current recommendations of vitamin D supplementation have nothing to do with something missing in breastmilk, but with changes in our lifestyle regarding sunexposure.

What does vitamin D?

Vitamin D is necessary for the uptake of calcium and phosphates in the gut. An impaired uptake of vitamin D combined with a minimum exposure to sunshine can lead to rickets, a disease that affects the bone growth in young children. Currently, rickets is present in 9 per million infants, mainly in infants with a darker skin. Rickets in older children declined after the fortification of cows' milk.

Recommendations

As of now, the AAP recommends that infants six months and under be not exposed to direct sunlight. After that, infants should be protected against UVB by application of sunscreen. To meet the requirements of vitamin D in infants and young children, supplementation of vitamin D is recommended by the AAP. By supplementing the infants, the effects of exclusive breastfeeding may be impaired. In children with severe allergies, administration of vitamin D drops may lead to problems. Care should be taken that babies do not receive an overdose of vitamin D. More research is needed to estimate the amount of safe and adequate sun exposure and safe and adequate vitamin D supplementation.

To supplement or not to supplement

The question is, if supplementation is safe. First, mothers may have difficulties in administering vitamin drops. Second, supplementation should be available in vitamin D drops only, not a multi vitamin preparation, since breastmilk contains adequate amounts of vitamins. Third, once mothers start to put something else in their baby's mouth than breastmilk, the step to feeding other drops, teas, medications, and foods may be lowered. This may have an impact on the time baby's are exclusively breastfed or the total duration of breastfeeding. Fourth: if mothers want to comply with vitamin D supplementation and find dosing the right amount difficult, they may prefer formula feeding.

Making healthy choices

Consult your physician about your child 's risk factor for not meeting the vitamin D requirements and the need for supplementation.