Vitamin D and breastmilk … what’s a babe to do?

You know that breastmilk, your milk, is the ideal and superior food for your baby.  It has immunological properties, just the right amounts of protein, fat, sodium, and fluid for your baby at his current age, and it changes depending on the time of day and when the last feeding was.  Even mothers who aren’t able to eat a great diet due to access to food, allergies, or other reasons, produce breastmilk that is nutritionally superior to anything else they can feed their babies.  Why, then, is there controversy over vitamin D?  Why do our pediatricians tell us to supplement our breastfed babies starting in the first few days of life, if we’re feeding them our complete, ideal milk?

The news you’ve heard is true: for many, many mothers, our milk does not confer the amount of vitamin D our babies need (400 IU/day) to protect them from rickets, a disease that causes softening and weakening of bones.  The American Academy of Pediatrics recommends in its 2008 policy statement:

“A supplement of 400 IU/day of vitamin D should begin within the first few days of life and continue throughout childhood. Any breastfeeding infant, regardless of whether he or she is being supplemented with formula, should be supplemented with 400 IU of vitamin D.” (Pediatrics 2008; 122(5):1142-52)

If our milk is ideal, “perfect,” even, why is a supplement recommended?  Is this another booby trap to make us think our own milk is inadequate?

Let’s start with a brief introduction to vitamin D.  It sounds like a nutrient, because we call it a “vitamin,” but it’s actually a pre-hormone, which gets converted in our bodies to another substance (1,25(OH)D).  The 1,25(OH)D then functions in our bodies to help regulate our blood calcium levels.  Of course, we know calcium is important for healthy bones, but you might not know that if your blood calcium is not quite right, you’re going to feel terrible.  Too much calcium and you’re going to lose your appetite, feel nauseated, fatigued; too little and your blood pressure will drop, your heart might not beat regularly, and you’ll struggle to stay standing, let alone functional.  In addition to calcium regulation and bone mineralization, vitamin D affects lots of other body systems, most notably our immune function and the cells in our pancreas that affect insulin production and blood sugar metabolism.  There is also observational evidence (studies that show a relationship but can’t necessarily prove cause and effect) that vitamin D is associated with such conditions as diabetes, rheumatoid arthritis, multiple sclerosis, prostate, breast, and colon cancers, and respiratory infections/flu, among others.  So, clearly, vitamin D is important in our bodies.  A vitamin D researcher, Dr. Reinhold Vieth says vitamin D is to the body as paper is to an office: the office can still do its business without paper, but operations will be compromised.

The problem for mothers and babies starts because many mothers are deficient in vitamin D in their pregnancies and after delivery.  One collection of data among women of childbearing age in South Carolina found that more than 50% of these women had vitamin D levels (measured by a blood test for 25-hydroxy-D, or 25(OH)D) lower than 20 ng/mL, and 81% of this same sample had vitamin D levels lower than 32 ng/mL.  While the Institute of Medicine’s 2010 report on vitamin D intake in the United States and Canada suggests 20 ng/mL as an appropriate level of sufficiency (because it is supportive of bone health, the only outcome that has been proven to have a cause-and-effect relationship with vitamin D), there are other data that recommend 30 or 32 ng/mL as a better measure of vitamin D sufficiency (because the observational outcomes regarding other diseases and vitamin D seem more favorable at this level).  Regardless of which standard we are applying, there is evidence that a large number of mothers are going into pregnancy with lower than optimal levels of vitamin D, which results in babies being born with lower levels, and the milk of mothers containing less than the ideal amount of vitamin D.

How did this happen?  We used to hear that we got enough vitamin D just from casual sun exposure on our face and hands, since our bodies produce vitamin D. We know now that isn’t necessarily true.  While our bodies make 10,000-20,000 IU of vitamin D after 15-20 minutes of unprotected sun exposure over most of our bodies (think swimsuit on the beach in July), if we live in northern latitudes (anywhere north of Atlanta, research shows), the sun’s rays can’t do their job for most of the year.  Basically, you can make snow angels outside, naked, all afternoon and not make any vitamin D if you live in New York and it’s February.  Those with darker skin colors will take up to 5 times as long to make the same amount of vitamin D under ideal conditions.  Remember, this is unprotected sun exposure … sunscreen blocks the vitamin D-making rays.  This is a big reason why we, as a population, are finding lower vitamin D levels.  The motivation to avoid skin cancer is legitimate.

The Institute of Medicine, in its report in November of 2010, recommends 600 IU/day as our daily intake, however, vitamin D is difficult to get from diet.  There are some foods that are fortified with vitamin D2 (our bodies convert that to D3, then convert the 25(OH)D to 1,25(OH)D), and other foods, like certain fish, that are naturally good sources of vitamin D; but most Americans get only 10% of their vitamin D from dietary sources.

In addition to how far away we live from the equator, there are other factors that affect our vitamin D status.  A body mass index over 30 is one; being over age 70 is another (and the IOM recommends extra vitamin D, 800 IU/day for this population). Of course, if we are inside most of the time and we use sunscreen or cover our bodies with protective clothing, even if we lived ON the equator, our vitamin D status would likely be lower than is optimal.

So, what’s a babe to do?  It is very important to keep in mind that breastmilk is still the superior infant food, and is, regardless of your vitamin D status, the very best you can feed your baby.  Your baby does need vitamin D, though, and you have options.

First, you can (and should) have your own level tested.  While the level required to make your milk have 400 IU/day of vitamin D is higher than most of us can achieve with the Institute of Medicine’s “tolerable upper intake” of 4000 IU/day (check with your doctor before supplementing with this much, there could be valid reasons this is NOT a good idea for your body), research by Dr. Carol Wagner and Dr. Bruce Hollis indicates that supplementing the mother with enough vitamin D to significantly raise her level can solve the problem of deficiency of both the mother and the baby, without toxicity to the mother and without having to offer anything to the baby other than mother’s milk.  It is important to note, however, that some of the data analyzed by the IOM revealed that the level of circulating 25(OH)D in a mother necessary for her milk to confer enough vitamin D to her baby may be associated with other, adverse health outcomes.  More research is needed in this area before a public health recommendation can be made with regard to high-dose supplementation of mothers in order to avoid the need to supplement the baby.

Of course, if a mother has her vitamin D level tested and she’s naturally replete, (a blood level over 50 ng/mL of 25(OH)D, for the purpose of fortifying her milk), her milk is also likely rich in vitamin D and there’s no need to supplement her or her baby.

If a mother has been deficient in vitamin D during her pregnancy, it could take months of supplementation to bring her status to adequacy; meanwhile, her growing baby needs vitamin D for bone health.  Sun exposure, as mentioned above, is how humans were designed to synthesize vitamin D; but sun exposure is a risk few families are willing to take (though it is an option at certain locations and under certain circumstances). Supplementing the baby with 400 IU/day of vitamin D, typically in drop form, is also an option you may wish to choose.  Many pediatricians recommend a “poly” vitamin supplement, but only vitamin D is necessary if you are breastfeeding your baby; ask for a vitamin D-only supplement.  They are widely available – just make sure you know exactly what a dose looks like, because many preparations provide the recommended amount in one single drop.

So, don’t fret, babes!  The vitamin D issue is an easy one to solve, and now you’ve got information to bring to your doctor/pediatrician so you can decide which solution is best for you and your baby!  Relax, enjoy these precious breastfeeding days, and feel confident that your milk is still the very best you can feed your baby.

Diana Cassar-Uhl, IBCLC and La Leche League Leader, has written articles for the La Leche League publications Leaven and Breastfeeding Today, and is the author of the La Leche League tear-off sheet Vitamin D, Your Baby, and You. She is a frequent presenter at breastfeeding education events. Eager to begin work on a Master of Public Health in 2011, Diana hopes to work in public service as an advisor to policymakers in maternal/child health and nutrition. Mother to three breastfed children, Diana has served as a clarinetist on active Army duty in the West Point Band since 1995. She enjoys running, writing, skiing, and cross-stitching if there’s ever any spare time. You can find more of Diana’s work and read her blog, “Normal, like breathing,” at

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38 Comments | Last revised on 04/08/2011

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