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Vitamin D Supplement for Breastfeeding Mothers: How Much?

Vitamin D is an incredibly important nutrient (technically, a hormone) that regulates numerous functions in the body, from blood sugar metabolism, to brain function, to thyroid health, to bone strength.

It seems to be involved, on some level, in just about every bodily system.

As I’ve written about before, vitamin D deficiency is both common and entirely treatable.

Since I specialize in prenatal nutrition, I tend to get a lot of questions about nutrition for breastfeeding. I’ve discussed it several times on the blog and in podcast interviews.

Breastfeeding is a unique time when nutrient demands are high, as both mom and baby are reliant on maternal intake or maternal nutrient stores.

Vitamin D Supplement for Breastfeeding Mothers: How Much?

Studies on the vitamin D content of breastmilk show that most women’s milk is low in vitamin D. This has led some to believe that vitamin D doesn’t transfer to breastmilk in sufficient quantities, but that’s an uneducated conclusion.

Why would breastmilk be a poor source of vitamin D?

Because most women don’t get enough themselves!

As vitamin D researcher, Dr. Bruce Hollis, explains:

“From the standpoint of nature, low vitamin D content in breast milk is an odd circumstance. Would nature allow so little vitamin D in breast milk that the nursing infant would develop rickets from ingesting it? We did not believe so. Our belief was that breast milk was deficient in vitamin D due solely to lack of solar exposure and dietary recommendations for vitamin D put forth in recent decades.“ (Pediatrics, 2015)

Breastmilk is SUPPOSED to have enough vitamin D in it for you and baby, but if you are not taking in enough vitamin D, there’s simply not enough to transfer into breastmilk.

This is the primary reason the American Academy of Pediatrics recommends supplementing breastfed infants with 400 IU per day (formula is fortified with vitamin D, so the levels are consistent, which is why this recommendation is solely for breastfed infants).

The problem is, few pediatricians get the word out and/or not many follow through with the advice. In fact, only 2-19% of infants end up supplemented with vitamin D. (Pediatrics, 2015)

That’s tragic, because early life vitamin D deficiency is extremely common:

“Vitamin D deficiency is almost universal among solely breastfed infants not receiving oral vitamin D supplementation.” (Pediatrics, 2015)

And it can lead to major problems, like rickets (extremely weak and brittle bones).

In my eyes, given everything we know about vitamin D, wouldn’t you want to correct the source of the problem – maternal vitamin D intake?

One fabulous study did just that. They compared maternal vitamin D supplementation (alone – at several different doses) to infant vitamin D supplementation (standard 400 IU).

This study tracked maternal and infant vitamin D levels at baseline, 4 months and 7 months (as well as vitamin D levels in breastmilk – measured as “antirachitic activity”).

The gist of their findings: Women receiving 6400 IU of vitamin D per day had higher vitamin D levels and passed enough vitamin D into their breastmilk to meet the demands of their baby (without the need to directly give the baby a separate infant vitamin D supplement).

(Side note: The study originally was trying to test lower doses of maternal vitamin D supplementation as well, but had to stop the 2400 IU arm of the study for ethical reasons, namely, because infants were not receiving enough vitamin D from breastmilk alone.)

What does this mean for breastfeeding moms?

You have the option to take vitamin D yourself (6,400 IU per day) to boost the vitamin D content of your breastmilk instead of giving a separate supplement to your infant.

To me, this a two-birds-with-one-stone situation.

Both you and your baby need vitamin D. Why not take it yourself?

One important note from this study: Don’t assume that the vitamin D levels in your breastmilk will be high if your blood levels are adequate.

Circulating 25-OH vitamin D does not readily transfer into breastmilk, but vitamin D (from sunlight, food and supplements) does.

This is counterintuitive, but a very important distinction to know about:

“Universally, the antirachitic activity of human milk is quite low, 5 to 80 IU/L, unless the lactating mother is ingesting a significant amount of vitamin D daily or getting significant total body UV exposure. It is the parent compound, vitamin D itself, which overwhelmingly gets transferred into human milk from the maternal circulation. This is an important yet almost universally misunderstood fact. Although circulating vitamin D readily gains access to human milk, circulating 25(OH)D does not, and this transfer relationship occurs over a massive range of vitamin D intakes and/or circulating levels. Thus, one cannot assume that because a lactating mother’s circulating 25(OH)D level is adequate, her milk vitamin D activity will be.” (Pediatrics, 2015)

Before you go, I’d love to hear from you:

Did your doctor/pediatrician recommend a vitamin D supplement (for either you or baby)?

Let me know in the comments below.

Until next week,

PS – Many people mistakenly believe they can get enough vitamin D by sitting outside in the sun for 15 minutes a few days a week or drinking milk. Be sure to read my post on vitamin D: 10 Things You Didn’t Know About Vitamin D for the truth on these common vitamin D myths.

PPS – Are you a research junkie like me? If you’d like to read the full study about vitamin D supplements and breastfeeding, it’s open access and freely available from Dr. Google:

Hollis, Bruce W., et al. “Maternal versus infant vitamin D supplementation during lactation: a randomized controlled trial.” Pediatrics 136.4 (2015): 625-634.

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Lily Nichols is a Registered Dietitian/Nutritionist, Certified Diabetes Educator, researcher, and author with a passion for evidence-based prenatal nutrition and exercise. Her work is known for being research-focused, thorough, and unapologetically critical of outdated dietary guidelines. She is the author of two bestselling books, Real Food for Pregnancy and Real Food for Gestational Diabetes.


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  1. My doctor has never said anything about any supplements except giving me a few samples of prenatal vitamins. I was recently diagnosed with gestational diabetes and have been trying everything to get my fasting sugars down. I’m wondering if lack of Vitamin D is part of the problem. I ordered your book and I’m waiting anxiously for it to arrive. I only have 6 weeks left and am afraid my baby has been exposed to unmanaged blood sugars for too long. Thank you for all the great information you’re putting out!

    • Yes, vitamin D does play a role in insulin resistance and deficiency can be one factor in gestational diabetes (though there are many, many potential factors to consider). There’s a section in my book, Real Food for Gestational Diabetes, specifically on vitamin D. See the supplement chapter for more! (And I go more in-depth on the topic in my online course. 😉

      Good luck with the final weeks of pregnancy, Jess. All of the work you’re putting in now to manage your blood sugar is absolutely worth it.

  2. Yes, my OB has tested my vitamin D level, and it is a little low. She has me on 2000 IU of D3 and has encouraged me to increase when I begin breastfeeding. I am currently 32 weeks pregnant with baby #4.

    • It’s good your doctor has tested your vitamin D levels and has you supplementing, Jennifer. The research on vitamin D and pregnancy shows that 4,000 IU is more effective at raising vitamin D levels than lower doses.

      “It is concluded that vitamin D supplementation of 4000 IU/d for pregnant women is safe and most effective in achieving sufficiency in all women and their neonates regardless of race, whereas the current estimated average requirement is comparatively ineffective at achieving adequate circulating 25(OH)D concentrations, especially in African Americans.”

      Might be worth it to discuss this research article with her: Hollis, Bruce W., et al. “Vitamin D supplementation during pregnancy: Double‐blind, randomized clinical trial of safety and effectiveness.” Journal of bone and mineral research 26.10 (2011): 2341-2357.

  3. Vitamin D supplement was recommended by my hospital regardless of formula or breast-feeding. However my pediatrician told me differently that breastmilk is completely sufficient and I should not have to supplement Thank you for this very informative article ! I will now be increasing the amount I take myself!

    • Yeah, sounds like your doctor didn’t get the full memo on vitamin D and breastmilk! Feel free to share this article with them.

  4. Nope. I have had 3 children, two are adults now, and three different doctors. Not one suggested vit. D. My oldest bf her first and then her second. But her second was taken to the ER one night due to a fall from his bigger sibling, (while on the ground, sitting (he didn’t walk, now we know why he didn’t have any teeth yet too) and nonstop crying. Then a whole case of child protection was involved. Come to find out it was due to a lack of vit. D. NOT ONE SINGLE DOCTOR suggested this. The doctor on the case still won’t admit it was the lack of vit. D, but the CASA worker, bless her! She is a hero. On a side note, the investigative officer on the case lied to me about the damage of the bone likening it to being smashed in a car door. There was never any outward sign of injury other than the crying. All charges have been dropped, but can you tell I’m still angry at the doctors and authorities about this? If we can’t trust the doctor’s who can we trust?
    Thank you for your blog. I wish I had seen this a year and a few months ago.

    • What an unfortunate and upsetting experience! I’ve heard similar stories from the Vitamin D Council about parents facing suspected abuse charges because of broken bones that were in fact caused by vitamin D deficiency (rickets). I’m so glad the charges were dropped and the case worker was up-to-speed on vitamin D. Wow.

  5. While not related to breastfeeding, I’m really interested in your feedback on the vitamin D article at this link:
    The practitioner of Chinese medicine who pointed me to this link advised me to stop taking vit D, said I was probably poisoning myself (I had been taking 5000 IU in winter).
    I don’t know how to reconcile such differing information!
    Thanks a bunch.

  6. I live in Uruguay and here all new mums are told to supplement their babys with vit D until baby is one year old. My son’s pediatrician told me to continue until summer becouse my baby’s​ birthday is in winter. I can’t believe we are doing something better than in the USA!!!

  7. I live in Uruguay and here all new mums are told to supplement their babys with vit D until baby is one year old. My son’s pediatrician told me to continue until summer becouse my baby’s​ birthday is in winter. I can’t believe we are doing something better than in the USA!!!

    • I bet there are a lot of things done better in Uruguay than in the US.

  8. I used to have a good doctor who was big on natural therapies, holistic medicine, etc. but then he moved to another state. 🙁 He did recommend vitamin D for me.

    I’d be interested to know how much vitamin D a pregnant woman should have (I’m sure the recommendations for that are way underestimated like many other nutrients). I’m about 12 weeks and also breastfeeding an 18 month old. My vitamin D levels are pretty low (33 in whatever measurement we use in Australia, 60+ is recommended).

    • I would suggest having your levels tested to determine a dosage. Since you’re still nursing, I’d use that as a starting point and fine tune a dosage with input from your healthcare practitioner.

  9. Months ago I asked my daughters pediatrician about vit d supplements for her. She told me that vit d supplements start at 6 months. My daughter is now 4 months old and I have yet to give her vit d because of what her doctor told me. Is it too late for me to start taking the recommended 6400 IU myself and supplement her that way? Would the vit d I start talking be immediately available in my breast milk? I am very worried. Thank you in advance.

  10. My pediatrician has suggested vitamin D drops for my baby at every appointment. Since I’d read your newest book prior to having my baby, I knew about vitamin d supplementation for myself. So I just told the dr I was doing it (knowing full well that drs don’t always keep up with the research) and took your recommended amount of 6,400 IU per day. I actually usually get more like 7,400-8,000 IU per day because I take a calcium supplement that also has vitamin d in addition to the vitamin d in my prenatal vitamin that I’m still taking and any in the milk I drink. This is my fifth baby though and it’s the first time I’ve ever been told to supplement with vitamin d. When my first four (born in 2007, 2008, 2010 and 2012), I got told to give them iron drops all the time. But never vitamin d. Now I get told vitamin d but not iron. I’m glad because those iron drops are gross!

  11. Hi! Is it safe to take 7400 of vitamin d? I ordered a lactation vitamin that has 6400 but my omega 3 has 1000 d3. Thank you!

  12. After reading your book for pregnancy, I asked my doctor if she thought we should test my vitamin D….she said, “oh no, if your eating dairy you should be just fine.” I was not convinced by her response, so I took your advise and have been supplementing 4,000iu each day. I’m 38 weeks now, and this post was so helpful to know how much to take while breastfeeding (very soon!). THANK YOU LILY! You’ve been THE. MOST. helpful resource, so naturally I tell evvvvveryone about your book!

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