In April of 2011, Best for Babes unveiled a new website, and I was thrilled to be the first guest for the “Making Sense of the Science” blog section. My article on vitamin D and breastfeeding has caused quite a stir on Facebook fan pages where its link was posted, such as The Leaky Boob and KellyMom, as well as on the blog post itself. Rather than try to answer all of the excellent questions that were raised (some more kindly than others!), I will try to clarify the major issues here. Be sure to read the article at Best for Babes, as this post relates directly to that. A reminder: I am an IBCLC, which stands for International Board Certified Lactation Consultant. I am not a doctor. It is not in my scope of practice as an IBCLC to prescribe or recommend a medical course of action to any mother/baby. I cite the recommendation that has been published by the American Academy of Pediatrics, but I also present other points for consideration, such as which factors an individual family might weigh when deciding whether to go with the AAP’s recommendation on vitamin D for breastfed babies … but at no time do I make a recommendation myself.
I wrote La Leche League International’s tear-off information sheet (Vitamin D, Your Baby, and You, 2010) after months of review of the literature, specifically the ongoing research by Drs. Carol Wagner, Bruce Hollis, and Sarah Taylor , which deals with the vitamin D status of pregnant and lactating women. This research is very new (first reports were published in May of 2010) and perhaps your OB/GYNs, midwives, and pediatricians have not yet come across it. This team’s studies are exactly what the National Institutes of Health/Institute of Medicine (IOM) have stated it needs more of (and is funding) in order to embrace vitamin D’s role in outcomes besides bone health: randomized, controlled trials. A fabulous, comprehensive resource about this research is the book New Insights Into Vitamin D During Pregnancy, Lactation, & Early Infancy, written by the researchers. I was fortunate to hear Dr. Wagner present at a La Leche League educational event in July of 2009. Before my exposure to Dr. Wagner’s work, I was, like many of you, very skeptical of any guidance that suggested my breastmilk wasn’t all my baby needed.
I believed “vitamins make expensive pee!” and I was emphatic about getting my nutrition from my Very Good Diet (really … it is Very Good). But, here’s the thing I learned right away: vitamin D isn’t a nutrient. It’s a pre-hormone, and most of us only get 10% of what we need from diet. This made me ask the question, as many of you are asking: why, then, do we feel like our babies need to get their necessary vitamin D from diet? Before I address this issue, let me comment on how the recommendation for 400 IU/day for babies was arrived at. This is the amount of vitamin D that has been proven, through lots of data, to provide adequate “antirachitic activity” (prevents rickets). This recommendation is based upon what the medical community knows about vitamin D and bone health. Should our babies be getting all their vitamin D from breastmilk/diet? Honestly, this is my million dollar question, one I can’t answer. What I can do is muse out loud a bit about the alternatives.
One option is to completely disregard the research that suggests babies need 400 IU/day of vitamin D and just breastfeed and hope for the best. Another is to completely buy into the AAP’s recommendation (which mirrors the IOM’s 2010 report) and supplement with 400 IU/day of vitamin D. Other options include measuring vitamin D status in mothers and supplementing them, which improves the vitamin D status of both mother and baby (and eliminates the need to give babies anything else by mouth except our milk); still another alternative is sun exposure for mother, baby, or both. Get out in the sun for vitamin D. Of course, this is the solution that our bodies were created to live within … but there are several valid reasons why this option does not appeal to some families. A brief lesson about how our bodies synthesize vitamin D after sun exposure: there is a cholesterol in our skin that ultraviolet-B rays from the sun activates. After 15-20 minutes of midday, mostly uncovered exposure for light-skinned individuals (at the right latitude or during the right season), a healthy body will synthesize 10,000 – 20,000 IU of vitamin D in the next 24 hours.
Those with darker skin tones may require up to an hour of exposure for the same benefit. The cholesterol in the skin converts the UV-B rays to vitamin D3, which is then converted by the body to the active hormone, 1,25(OH)D. (Keep in mind that many doctors unknowingly measure this 1,25(OH)D value, which may even be elevated in individuals with a 25(OH)D deficiency.) A body can’t “overdose” on vitamin D from the sun, because once the body has enough, synthesis shuts down (oral toxicity is possible, but improbable at sensible supplemental levels). Vitamin D is fat soluble and is stored in the body. Some postulate that we store up enough in the summer to carry us through most of “the dark season,” but start to really crave sunshine come February! Anecdotally, some claim they avoided seasonal depression by supplementing with vitamin D throughout the winter. Perhaps, but randomized, controlled trials are being conducted to support or refute this theory. Please note: the old recommendation of 15 minutes a day of sun exposure to hands and face (which your doctor may still believe), year-round is not accurate.
Sun exposure alone may not be adequate for your body, or it may be … I don’t know, but the data I’ve seen in the 3 years I’ve spent on this topic suggests there are widespread insufficiencies of vitamin D. My doctor says my level is fine. This is another major point of contention in the medical community: the definition of vitamin D sufficiency. As I stated in the article, the IOM sets 20 ng/mL of circulating 25(OH)D as “generally considered adequate for 97.5% of the population” and a level under 12 ng/mL as deficient (for bone health). This level of vitamin D is fairly easy to arrive at with the current Recommended Daily Intake of 600 IU/day, and is sufficient for bone health. However, there are smart people who suggest (and have data to support) that 32 ng/mL of circulating 25(OH)D is sufficient; levels between 20-32 ng/mL are “insufficient” and deficiency is defined by a level under 20 ng/mL. There are other physiological factors taken into consideration when defining vitamin D sufficiency, such as the level at which calcium is best absorbed, the level at which bones are well mineralized, or the level at which parathyroid hormone is stable.
It is interesting to note that the IOM, in its review of data for its 2010 report on vitamin D intake, discovered adverse effects in some people whose circulating 25(OH)D was over 50 ng/mL. In another corner we find Hollis, Wagner, and Taylor’s published findings from their RCT’s. Their work focuses specifically on pregnant and lactating women. One aspect of study involves 3 groups of pregnant women, after the 12th week of gestation (double-blinded so neither the researchers nor the subjects know what group they’re in): one group is supplemented with 400 IU/day of vitamin D; one with 2000 IU/day, and the third group with 4000 IU/day. The incidence of negative pregnancy outcomes, such as pre-eclampsia and preterm labor/delivery, is significantly reduced in the 4000 IU/day group, plus, the breastmilk of those mothers has more of that “antirachitic activity.” There have been no adverse effects of the higher dose of supplemental vitamin D reported in any mothers or babies that have participated in this study.
More results are being published as additional cohorts complete the trials. For lactation, preliminary findings indicate that a mother’s circulating 25(OH)D level needs to be at 50-60 ng/mL in order for her milk to provide all the vitamin D her baby needs. At lower maternal circulating 25(OH)D levels, there is still vitamin D being conferred through breastmilk, just less. Again, for me, this begs the question: should babies get their full daily complement of vitamin D from breastmilk? Keeping in mind that there is data suggestive of such high circulating 25(OH)D levels being harmful over time in some individuals (one report showed higher incidence of prostate cancer in a group with a 25(OH)D level over 50 ng/mL … I don’t have a prostate but should I worry?), and also knowing, both from research and personal experience how difficult it can be to reach that 50-60 ng/mL level of circulating 25(OH)D, even with abundant supplementation (preliminary findings suggest 6400 IU/day, nearly 11x the current RDI) …
I’m leaning toward a combination approach. Let me remind you: I’m not a doctor, and I’m just thinking out loud here – but, looking at the options available for ensuring adequate vitamin D status for me and my children, I like a multi-faceted approach. Maybe moderate supplementation for me (or more aggressive supplementation when I’m pregnant and breastfeeding an infant), occasional supplementation for my children, and conservative sun exposure might take care of our vitamin D needs? I don’t know for sure. All of this information is still so new – and not just to me. When your doctor says “your vitamin D status is fine,” by which standard is he defining “sufficiency?” Does he value any of the still-being-studied claims that higher levels of 25(OH)D might affect conditions other than bone health, such as diabetes, certain cancers, multiple sclerosis, and respiratory illnesses? It’s a lot to consider, and frankly, the vitamin D controversy remains huge in the medical community, not just among us breastfeeding mothers.