A new randomized controlled trial reports, if you dose adequately, the breastfeeding mother can provide vitamin D in her breast milk by either single large monthly dose or by daily supplementation.
In breastfeeding, the parent compound vitamin D3 gets passed from the serum to the breast milk and onto the infant, rather than 25(OH)D getting passed on through the breast milk (which is the circulating form of vitamin D and the form the body turns into activated vitamin D). Since the breastfeeding mother cannot pass her circulating form of vitamin D [25(OH)D] through the breast milk, she must rely on getting adequate vitamin D through either good sun exposure habits, supplementation or both.
Since there is this challenge of needing lots of regular maternal vitamin D input, it has been conventionally thought that it is crucial that breastfeeding mothers should make sure they get vitamin D regularly and without skipping a day, otherwise she would have no vitamin D to pass onto her infant and the baby would suffer from vitamin D deficiency.
In the present study, however, researchers from the Mayo Clinic wanted to examine this. They wanted to know, what happens if we give the breastfeeding mother a high single dose, instead of daily doses? Would the baby still get enough vitamin D?
They randomized 40 mothers to take either a single vitamin D dose of 150,000 IU or to take 5,000 IU/day for 28 days. They measured maternal 25(OH)D and amount of vitamin D in breast milk at 0, 1, 3, 7, 14 and 28 days. They measured infant 25(OH)D at 0 and 28 days. Mean infant age at the start of the study was 13.7 weeks in the daily dose group and 11 weeks in the single dose group.
Here’s what they found:
- At baseline, mother’s 25(OH)D levels were about 29 ng/ml in both groups. Infants 25(OH)D levels were about 16 ng/ml.
- In the daily dose group, maternal 25(OH)D increased steadily over the trial, ending up at 43.9 ng/ml at day 28. The breast milk, after containing little vitamin D the first day, contained about 8 ng/ml of vitamin D on days 3, 7, 14 and 28. Thus there was some consistency each day on how much vitamin D was being delivered to the baby.
- In the single dose group, maternal 25(OH)D increased sharply, peaking at 50 ng/ml after 3 days and then declining slowly to 41.2 ng/ml at the end of the trial. The breast milk had lots of vitamin D in it immediately: 39.7 ng/ml at day 1, 24.6 ng/ml at day 3 and 11.2 ng/ml at day 7. At days 14 and 28, however, the breast milk contained little vitamin D.
So the question remained, did the infants who got breast milk from the single dose get enough vitamin D at the beginning days of the month to last them for 28 days? Were they able to compare to the infants who got vitamin D daily throughout the month?
Here’s what they found:
- After 28 days, the infants feeding from daily dosed mothers had 25(OH)D levels of 39.2 ng/ml.
- After 28 days, the infants feeding from single dosed mothers had 25(OH)D levels of 38.7 ng/ml.
The researchers concluded,
“Either single-dose or daily-dose maternal cholecalciferol can provide breast milk concentrations that result in vitamin D sufficiency in their infants.”
One drawback of the study is that they did not measure 25(OH)D levels in the infants more throughout the trial. One concern you might have is just how high were the infants’ levels after 3-7 days? Since they didn’t draw for the infants on those days, we don’t know.
Vitamin D deficiency in exclusively breastfed infants is a major public health concern. As we’ve discussed, unless mothers are getting plenty of vitamin D during breastfeeding, much more than traditionally recommended, they’re probably not passing much vitamin D onto infants, thus leading to vitamin D deficiency in their infants.
For mothers who have a hard time supplementing regularly, supplementing with a large single vitamin D dose at a specific date in the month might be good strategy.
This can be a complicated topic because of discussion of parent-compound vitamin D vs 25(OH)D, so if you have any questions or would like me to clarify on anything, please leave your questions in the comment section and I’ll be happy to respond.