Vitamin K in Breast Milk - Can it replace 'the shot'?

Updated: Mar 11

Before I become a mother, I had no idea how controversial parenting is! Drugs or no drugs during childbirth? Delayed cord clamping? Circumcision for boys? To 'vax' or not to 'vax' – delayed or maybe just a select few? Bed-sharing? Sleep training? Breast or bottle – and for how long?

The list of topics starting #mommywars goes on. Most parents just want to make the best decisions for their little one(s) - but it’s not always easy! There is a lot of information – and misinformation – out there, and often times it comes down to this:

Weighing risk vs. benefit in your child’s unique situation.

The Vitamin K injection for newborns is a good example of an intervention which has started some debate lately. Routinely administered to newborns within hours after birth to prevent Vitamin K Deficiency Bleeding (VKDB, aka “Hemorrhagic Disease of the Newborn”), the 'Vitamin K shot' has been routine practice in the US and most other developed countries since the 1960s (1). In the US, 1 milligram of Vitamin K is administered via intramuscular (IM) injection to most newborns within hours after birth. Studies have shown this to be the most effective way to reduce the risk of VKDB (2). A licensed oral preparation is not available in the US. Some countries offer oral administration, spaced out between birth and the first few weeks of life instead. In Germany, Vitamin K is usually given by mouth three times over the course of the first 4 to 6 weeks of life at 2 milligrams each (a total of 8 milligrams).

Why so much controversy over a simple Vitamin?

Vitamin K is a fat-soluble Vitamin needed for blood clotting. It crosses the placenta only in very small amounts (3), and a newborn’s Vitamin K stores are therefore very low. Newborns and infants up to the age of 6 months of age can develop hemorrhagic bleeding as a result of a Vitamin K deficiency (“Vitamin K Deficiency Bleeding”). The bleeding can be harmless or severe, resolve quickly or lead to permanent injury, or even death. Common bleeding sites include the umbilical cord, skin, nose, circumcision site, intestine and brain. Bleeding in the brain is the most serious complication as it is often undetected for quite a while (since babies can't tell us they have a headache, are nauseous or have a sudden change in vision). It can lead to permanent (stroke-like) damage to the brain or even death.

Nonetheless, the Vitamin K shot is increasingly declined by many parents.

Some moms fear the relatively high dose injected directly into the muscle (‘intramuscular’) raises Vitamin K levels in newborns to potentially harmful levels. Considering an adult’s recommended intake is only around 10% of the injected dose (4), this concern is very understandable. A newborn’s liver is indeed immature at birth and very high doses (25 milligrams or more) of Vitamin K can lead to elevated serum bilirubin concentrations leading to yellowing of skin and eyes (5). However, a dose of 0.5 to 1 milligram, as recommended by the American Academy of Pediatrics, does not seem to have any proven negative side effects in most newborns (1).

It may help to understand that the intramuscular (IM) injection of Vitamin K is NOT the same as an intravenous (IV) injection. In an intravenous injection, the material is injected directly into the bloodstream, raising blood levels quickly and to the full extend. The intramuscular injection, however, raises blood levels only to some extend following the injection. The muscle then stores and acts as a ‘depot’ for Vitamin K, releasing it slowly over the course of the following weeks/months (6). This is an intended depot-effect, as the risk of VKDB remains for up to the first 6 months of life. This is also the reason why the alternative, the oral administration in some countries, must be given multiple times over the first few weeks to have a similar protective effect.

Some parents fear the ‘other’ ingredients in the injection (such as preservatives, stabilizers, pH balancing agents) may be carcinogenic or cause other harmful side effects. I am not a chemist or pharmacist, but I found a good summary at Evidence Based Birth (see here) which explains the use of these quite well.

Another fear many moms have about the Vitamin K shot stems from a study published in 1990, which raised concern about a possible link between the Vitamin K shot and childhood cancer (7). Although more studies have since refuted the claim (8, 9, 1), many believe adverse side effects of this or similar nature are possible. While there is no evidence for it, I can completely relate to the fear of a yet unknown negative side effect.

Many also feel the Vitamin K shot is an unnecessary intervention as VKDB is relatively rare. Indeed, according to the Policy Statement by the American Academy of Pediatrics (1), late VKDB (bleeding between weeks 2 to 12 after birth) occurs only in about 4.4 to 7.2 newborns per 100 000 births not receiving the Vitamin K shot. The incidence for early VKDB (within the first week of life) is much higher at 0.25 to 1.7% (250 in 100 000 to 1700 in 100 000 births).

Truth is, most babies who do not receive the Vitamin K shot at birth won't experience bleeding problems. You will therefore most likely hear from moms who say "I declined the shot for my children, and they are all healthy." However, research definitely shows the administration of Vitamin K definitely reduces the risk of VKDB significantly (1) and the risk of bleeding without the Vitamin K shot is higher.

Why are babies born with low Vitamin K stores?

Last but not least, many believe there must be a reason why babies are born with low Vitamin K stores. In a way, it goes against the thought of ‘Mother Nature knows best’. - Why would this ‘Miracle of a Developing Life’ have such a fundamental flaw, requiring immediate human intervention right after birth? This was actually my main concern, and the reason I started reading up on the subject.

I can only speculate on the answer to this. Most nutrients transfer readily from mother to baby (both in utero and into the breast milk). In case of a deficient intake, it usually depletes a mother’s stores rather than taking away from baby's supply. With Vitamin K, it seems to be the opposite. Vitamin K crosses the placenta poorly, and breast milk is also considered to be low in this nutrient. It seems, maintaining mom's Vitamin K stores is of higher importance in Mother Nature's plan. Since Vitamin K plays such an essential role in blood clotting, it may just be the mechanism in place to prevent a mother in childbirth from bleeding excessively and dying from a high loss of blood.

Is it possible to increase Vitamin K in breast milk

through diet or supplements?

In a study by Thijssen and colleagues (10), researchers looked at the effect of Vitamin K1 (also known as “Phylloquionone”) supplementation on Vitamin K levels in breast milk.

Mothers were given 0.8, 2.0, or 4.0 milligrams of Vitamin K1 or a placebo daily between days 4 and 16 after the birth of their child (on a side note, most adults usually consume around 0.09 milligrams Vitamin K per day).

They found a ‘dose-dependent’ correlation between the supplemented amount and breast milk Vitamin K (this means, the higher the dose of Vitamin K received, the higher the levels in breast milk). Interestingly, supplementing with Vitamin K1 also increased the levels of Menaquinone-4 (MK-4), a Vitamin K2 subtype believed to be of great importance as it may be the preferred form of Vitamin K for cells other than the liver. The researchers suspect, MK-4 may be of special benefit for the newborn infant as the breast appears to have a mechanism in place to convert some of the Vitamin K1 to MK-4. The group concludes:

“Phylloquinone supplementation to lactating mothers may be of benefit to the newborn infant, since both phylloquinone and menaquinone-4 are raised by supplementation”. Thijssen, 2002 (10)

A study comparing the milk of mothers living in different parts of Japan found differences in Vitamin K concentrations and contribute this to differences in their dietary habits (11). In particular, fermented soybeans (a.k.a. Natto) seem to be a significant source of Vitamin K2 in some parts of this population.

A group at the University of Wisconsin also found that 2.5 and 5.0 milligrams of Vitamin K1, supplemented daily to women in the postpartum period, significantly increased the Vitamin K1 content of human milk. They further determined, this increase in milk Vitamin K also led to higher infant blood plasma concentrations of Vitamin K and decreased a marker indicating Vitamin K deficiency (Greer 1997). This finding is significant, as it shows Vitamin K from breast milk actually reaches the infant and can decrease the risk of a Vitamin K deficiency.

A few more (old) studies (12, 13) further support the idea that breast milk Vitamin K can be increased by supplementing the nursing mother with Vitamin K. Unfortunately, I could not find more recent clinical studies or one looking directly at whether a diet high in Vitamin K can actually prevent Vitamin K Deficiency Bleeding. Further studies are definitely needed!

How much Vitamin K to increase the levels in breast milk?

It looks promising that a diet rich in Vitamin K can significantly increase Vitamin K in breast milk. However, no significant increase in breast milk Vitamin K was observed in a study where the average Vitamin K supplementation was only 88 micrograms (= 0.088 milligrams) (14), which is just about the amount of Vitamin K in a standard American diet.

In order to increase breast milk Vitamin K, the intake needs to be higher than what most of us usually consume.

According to another study by Greer, a supplement of 5 milligrams of Vitamin K daily to lactating mothers increases the concentration in human milk to about 80 nanograms per milliliter (15). For comparison, most infant formulas have around 50 to 60 nanograms per milliliter of Vitamin K. Vitamin K1 supplementation anywhere from 2 to 5 milligrams of Vitamin K per day seemed to lead to a significant increase of Vitamin K.

Whether this increase actually leads to a decrease in Vitamin K Deficiency bleeding has not yet been studied. It has also not been studied if supplementing Vitamin K2 is better than supplementing with Vitamin K1, although it appears that Vitamin K1 can be converted into Vitamin K2 in breast tissue (10), supplying the infant with the valuable Vitamin K2 regardless of the type of Vitamin K supplemented. I personally believe a combination of the two (K1 and K2) is best.

Can I get 'too much' Vitamin K?

According to the Institute of Medicine (4), there is no known toxicity associated with Vitamin K1 or Vitamin K2 and abnormal clotting is not related to excessive Vitamin K intake. Despite its fat-soluble nature, the body has limited storage capacity for Vitamin K and recycles it in the Vitamin K Oxidation-Reduction Cycle. Personally, I believe common sense tells us that 'Megadoses' should still be avoided.

Can I avoid the Vitamin K Shot if I consume additional Vitamin K while breastfeeding?

At this time, it is too early to assume a diet rich in Vitamin K or taking Vitamin K supplements can replace the Vitamin K shot at birth. However, research definitely suggests it is possible to increase Vitamin K in breast milk through diet and/or supplements and this, in turn, can possibly decrease your child's risk of suffering from a Vitamin K deficiency. Hopefully, more studies are conducted in this area in the future so that the Vitamin K shot does not need to be administered routinely to all newborns. If you plan to decline the Vitamin K shot for your newborn, or plan on only giving a one-time oral dose, and you plan on breastfeeding, your doctor may recommend to increase your own Vitamin K intake. (But please discuss this with your doctor, because the information I present to you does NOT replace a thorough discussion with your trusted medical care provider!)

Ways to increase mother's and baby's Vitamin K intake

1. Eat your ‘Dark Green Leafy Vegetables'.

By far the highest Vitamin K1 content is seen in Kale, Collard Greens, Spinach, Turnip Greens, Mustard Greens and other vegetables of the ‘dark green and leafy type’. As you can see in the green table below, 1 cup of boiled Kale delivers over 1000 micrograms (= 1 milligram) of Vitamin K1. Collard Greens, Spinach and other types of Dark Green Leafy Vegetables contain slightly less but are still a main source of Vitamin K1.

In order to achieve an intake of 2 milligrams of Vitamin K1 per day, you would need to consume about two cups of frozen, cooked Kale or Collards, or slightly more Spinach or Turnips. (Note: µg is the symbol for 'microgram'. 1000 micrograms equal 1 milligram)

2. Prepare meals with plant oils.

Plant oils such as soybean, canola, olive, and cottonseed contain Vitamin K which is highly bioavailable (meaning the body can better absorb it). Vitamin K is fat-soluble, which means it is soluble in lipids (fat, oil, butter etc.) but not water. It actually needs fat globules to be absorbed into and transported through the blood stream. In moderation, plant oils can therefore contribute greatly to achieve a higher Vitamin K intake.

In addition, adding oils (or butter) to green vegetables boosts the absorption of Vitamin K1 (and other fat-soluble Vitamins). However, don't add the fat during the cooking/steaming process, otherwise the Vitamin K will leach into the cooking water! Wait and add it to your vegetables after you have drained excess water.

3. Fermented and animal products are sources of Vitamin K2.

While green leafy vegetables and vegetable oils are sources of Vitamin K1, meats and cheeses are the main sources of Vitamin K2 in the western diet. Not listed in this table is "Natto", a product made of cooked soybeans, fermented by bacillus subtilis natto, which is supposedly very high in Vitamin K2. While I couldn't find any information on the Vitamin K2 content of Natto in the USDA Nutrient Database, a study by researchers in Japan (16) lists Natto as containing 939 µg of Vitamin K2 in the form of MK-7, making it by far the food with the highest Vitamin K2 content.

4. Build and maintain a healthy intestinal flora.

Bacteria of the large intestine can synthesize Vitamin K2, which can then be absorbed in limited amounts into the blood stream. A newborn's intestinal flora is still immature, but a vaginal delivery as well as breastfeeding generally helps to grow beneficial bacteria in the gut. A mother can therefore potentially increase her own Vitamin K2 status by maintaining a healthy gut flora herself, thus possibly sending 'more' Vitamin K2 to the breast milk, as well as pave the road for baby's own Vitamin K2 production by delivering vaginally (if possible) and breastfeeding.

5. Let Baby nurse long enough on one side to get more of the higher fat milk (“hind milk”)

As I’ve mentioned above, Vitamin K is a fat soluble Vitamin. Not surprisingly, a 1991 cross-sectional study (17) found Vitamin K to be localized mainly in milk fat globules. The concentration of Vitamin K in breast milk is therefore directly correlated with the milk fat content. Higher concentrations of milk fat are usually seen in colostrum and hind milk. Each nursing session should therefore be long enough to give baby a chance to get to the nutrient-rich 'hind milk'.

6. Supplement, if necessary.

Of course it is better to get your Vitamins from foods, rather than supplements. For one, you do not run the risk of accidentally consuming a potentially harmful 'Megadose'.

Bioavailability is also generally higher in foods versus supplements. Dietary supplements also do not require FDA approval before being sold. They may therefore not contain the claimed amount and form of a Vitamin as labeled.

However, it is certainly difficult to achieve an intake of Vitamin K as used in the studies above (2.0 to 5.0 milligrams = 2000 - 5000 µg) to achieve the desired results. It is certainly easier to do this via the consumption of a daily supplement.

Please always consult your doctor and pediatrician before adding a supplement to your diet while breastfeeding.

What about "Stinging Nettle Tea'?

Some sites claim "Nettle Tea", or "Stinging Nettle Tea", is a great way to boost Vitamin K in breast milk. Unfortunately, my research could not confirm this statement.

While 'blanched Stinging Nettles' appear to contain significant amounts of Vitamin K - 499 µg in a 20 gram serving (18), the Vitamin K content in the actual brewed tea is more than likely very low. The reason lies in the fat-soluble nature of the Vitamin. It more than likely would not 'dissolve' into the hot water during the brewing process. One would have to consume the stinging nettle leaves themselves, but in that case, you might as well stick with Spinach & Co..

In the Japanese study I cited above (16), where different foods and beverages were tested for their Vitamin K content, natural leaf tea contained almost 2000 µg of Vitamin K1 per 100 grams of actual leaves, but the brewed version ended up containing less than 1 µg. The same can be expected with Stinging Nettle Tea.

Technically, one could add milk or another liquid containing fat globules during the steaming process to dissolve some of the Vitamin K in the fat globules; or use a tea powder (Green powdered tea contained over 3000 micrograms of Vitamin K1 in this study, since you would consume the powder as well).

However, I would not recommend to consume stinging nettles in large amounts as their safety while breastfeeding has not yet been established (see Drugs and Lactation Database here). They are considered to be 'likely unsafe' to take during pregnancy, according to the Natural Medicines Database, as they might stimulate uterine contractions and can cause miscarriage.

In conclusion (finally!)

1) Dark green, leafy vegetables and vegetable oils are great ways to boost one's Vitamin K1 intake, while meats (especially chicken), cheeses and fermented soybeans are a great source of the valuable Vitamin K2.

2) Oils and other fats increase the absorption of Vitamin K.

3) By consuming more Vitamin K-rich foods, building a healthy intestinal flora and making sure baby nurses long enough to reach the nutrient-dense hind milk, it is possible to decrease your baby's risk of suffering from a Vitamin K deficiency.

4) Whether this is enough to prevent the potentially dangerous "Vitamin K Deficiency Bleeding" is not yet known.

5) If you are currently pregnant, I strongly recommend you consult your doctor and pediatrician about the Vitamin K shot. Please also read my disclaimer and remember that none of the information on this blog is intended to be or replace medical advice.

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