It is a fact that breast milk is the superior source of nutrition for an infant in the first year of life. The benefits for exclusively breastfeeding are great and that will require an article of it’s own, but if it is so great then why do we need to supplement breast milk with vitamin D? Let’s discuss it.

What you will find in this article:

  • What makes breast milk so good?
  • What is vitamin D?
  • How is vitamin D made?
  • Why is vitamin D important for your health?
  • Why do you need to supplement breast milk with vitamin D?
  • How much vitamin D gets to your baby from mom?
  • How to give your baby vitamin D drops
  • Considerations for mom taking vitamin D supplement while pregnant or breastfeeding
  • Vitamin D deficiency in women

Why do you need to supplement breast milk with Vitamin D?

Supplement Breast Milk with Vitamin D

What makes breast milk so good?

The composition of breast milk is complex and provides a wealth of benefit to your baby. It contains factors that support development of the baby’s gastrointestinal tract, as well as providing antimicrobial properties which prevent and fight infections.

Expert pediatricians recommend that breastfeeding be the sole source of nutrition for the first 6 months of an infant’s life. Isn’t it amazing that our bodies are able to sustain another life even after we give birth? 

With something so good, it may seem a little strange that we need to supplement breast milk with vitamin D. 


Let’s start by talking about what is vitamin D?

Sure, we all have heard about it and realize it has something to do with the sun. We see foods or drinks marketing that it is fortified with vitamin D. We know we need vitamin D, but why?

Vitamin D is a fat soluble vitamin that is pertinent to aid in the absorption of calcium. Without proper calcium supply, your bones will become brittle and leave you susceptible to osteoporosis and fractures.

Severe lack of vitamin D in children puts them at risk for rickets, which is a failure of proper bone development. Vitamin D is the quiet kid who works behind the scenes at the school play. Without it, the rest of the body’s growth and development would suffer.

Contrary to what you may believe with food marketing: very little vitamin D that is available for our bodies to use, is present in our diet today.

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supplement breast milk with vitamin d

How is vitamin D made?

The majority of vitamin D comes from dermal synthesis, meaning it is created in the skin.

What did I just say? How does our skin just make a vitamin?

*Enter the sun stage left*

A miraculous thing happens at the chemical level of our body when our skin is exposed to UV rays. I know what your thinking, UV rays = skin cancer. And you’re right. Read more about protecting your skin here.

In overabundance and without proper skin protection UV rays cause skin cancer, but that’s not what we are talking about here. I am talking about the 10-15 minutes of sun exposure necessary for this chemical process to occur.

So let’s review.

You spend a small duration of time in the sun every day. A beautiful process happens converting inactive vitamin D in our skin to vitamin D that can be used in our bodies.

The vitamin D has a vital role in working with calcium to promote bone growth and development.

The problem is, not everyone gets enough sun exposure to promote the synthesis of vitamin D in the skin. Especially people who may live in cold climates. Or hello, New England, where I live, you literally can go from snow one day to 70 degrees the next. 

Now do you see why we need to ensure our bodies are receiving the needed vitamin D supplement?

Vitamin D as it Relates to Your Baby

Vitamin D in Utero

Vitamin D is transferred across the placenta, so your baby was receiving all she needed when in utero. That is, if mom was not deficient herself.

Vitamin D Deficiency in Women

I would bet more women are deficient in vitamin D than they realize.

Several years ago, I had routine blood work done for the first time in a while, and I learned my levels were at the low end of the normal range. So essentially I considered myself deficient because I was literally 1 point away from it. That is the day I started taking a supplement of 1000mg per day in addition to my calcium with D.

Read more about the vitamins you should be taking while pregnant or breastfeeding

How Much Vitamin D gets into Breast Milk?

The amount of vitamin D that is present in breast milk is 15-50 iu/L, and the American Academy of Pediatrics recommends infants receive 400iu of vitamin D per day.

Therefore, to put it into perspective for you, if an infant consumes 750ml of breast milk in a day they are only receiving 10-40iu/day of vitamin D. That is far below what their little body’s need for proper development of their bones.

Do you see the significance now?

Let’s not forget our friend, the sun.

Remember his role in all of this? How much sun do infants tend to get? Not much, right?

Well, in light skinned individuals it is recommended to have 10-15 minutes of exposure to arms and face between the hours of 10a-3p to promote synthesis of vitamin D. In dark pigmented people they may require 6-10x that length of time. So the sun is our friends in moderation.

How to give your baby the vitamin D drops?

It is okay to put the vitamin D drops you get into the breast milk.

I know my baby does not like the taste of it. She actually vomited it up when I first gave it to her by the dropper, unknowingly of the potential response.

This may be a reason why some women become uneasy of having to supplement breast milk with vitamin D. Some women choose another tactic of supplementing themselves with larger doses of vitamin D instead. 

Can mom take extra vitamin D instead of having to supplement breast milk?

I have read that women can take 4000-6400iu of vitamin D per day to allow enough to pass into breast milk, but I have a problem with this for two reasons.

First, you don’t know for certain how much vitamin D is actually getting into the breast milk and subsequently to your baby.

Second, you risk vitamin D toxicity because it is a fat soluble vitamin and the excess does not just get excreted in your urine.

The recommended max dose of vitamin D in women is 4000iu per day. I would not suggest this method to supplement your breastfed baby.

Why it is important to supplement breast milk with vitamin D?

So for the well being of your baby, consider all of these factors when it comes to proper supplementation of vitamin D in breast milk. Remember the vital role it plays in growth and development.

I hope I was able to make it clear why it is so important to supplement breast milk with vitamin D. 

Also, I congratulate you on your decision to exclusively breastfeed your baby! You are doing an amazing thing, mama!

Questions? Let me know in the comments below.

xoxo Tazia

*information for this article is sourced from UpToDate, an evidence-based clinical decision support resource from Wolters Kluwer.

Schanler, Richard J. MD. (2017). Infant benefits of breastfeeding.

Schanler, Richard J. MD. (2017). Nutritional composition of human milk for full-term infants.

Mirsa, Madhusmita MD, MPH (2016). Vitamin D insufficiency and deficiency in children and adolescents.

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