All About: Vitamin K

Vitamin K is an essential vitamin needed for blood clotting. Vitamin K is necessary for our bodies to activate certain molecules (also known as clotting factors) that help the blood to clot. If we do not have enough Vitamin K, then we cannot activate these molecules. Therefore, a Vitamin K deficiency makes our blood less able to clot. For the most part, our bodies can continue to clot appropriately with low Vitamin K levels. However, as the levels get lower and lower, we can suddenly reach a point where our bodies can no longer clot and we start to bleed spontaneously. The level that you have to get down to for bleeding to start varies from person to person. 

Humans do not make Vitamin K, and we don’t store it very well in our body. We get Vitamin K1 (also known as phylloquinone) from leafy green vegetables. We get Vitamin K2 (menaquinone) from bacteria that live in our intestinal tracts. Fun fact: Vitamin K1 from plants makes up about 90% of our overall Vitamin K levels, while Vitamin K2 from bacteria makes up only about 10%… so make sure you’re eating those leafy greens!

Babies and Vitamin K

Babies are born with very limited amounts of Vitamin K. Their levels are lowest at days 2-3 and do not reach adult levels until about 6 months of age.

The levels are low because: 

• Very little Vitamin K1 transfers from the mother to the baby through the placenta

• Babies do not have enough bacteria in their intestines to make Vitamin K2 

Body milk has very tiny amounts of Vitamin K. Levels in body milk and colostrum are similar— about 1 to 9 micrograms per liter. Levels are about 1 microgram per liter higher in hindmilk (the milk the baby gets towards the end of a feeding) than foremilk. 

In contrast to body milk, formula has relatively high levels of Vitamin K1 — 55 micrograms per liter. On average, babies who are fed formula receive nearly 100x more Vitamin K1 than babies who are breastfed. 

Daily oral supplements of 2-5 mg for the feeding parent are necessary to obtain similar levels of Vitamin K in breast milk, and could raise Vitamin K levels in the baby. So far, researchers do not have any evidence that the feeding parent intaking Vitamin K1 makes a difference in the rates of actual Vitamin K deficiency bleeding in infants.

Vitamin K Deficiency Bleeding

A baby who does not have enough Vitamin K can start to bleed suddenly, without warning. This is known as Vitamin K deficiency bleeding, and it can follow one of three patterns: early, classical, and late. 

Early VKDB happens in the first 24 hours of life. Early VKDB is usually seen in babies born to parents who took medicines that interfere with Vitamin K. These medicines may include warfarin (Coumadin), seizure medications, and tuberculosis medications. The bleeding usually happens in the skin, brain, and abdomen. 

Classical VKDB happens in days 2-7 of life, usually during days 2-3. This is when levels of Vitamin K are lowest. Common bleeding sites include the gastrointestinal system, umbilical cord site, skin, nose, and circumcision site. Classical VKDB is more common than late VKDB. Recent reviews show that the number of babies who will experience classical VKDB if they don’t receive Vitamin K at birth is 0 - 0.44% (0 - 440 out of 100,000). This type of VKDB is usually mild and involves bleeding at the umbilical cord site or circumcision site. However, blood loss can be significant. 

Late VKDB happens after the first week of life, usually during weeks 3-8. The bleeding usually happens in the brain, skin, and gastrointestinal tract. Bleeding in the brain is often the first sign of late VKDB. Late VKDB happens in exclusively breastfed infants who did not receive a Vitamin K shot. Some infants may also be at higher risk if they have undetected gallbladder disease, cystic fibrosis, chronic diarrhea, and antibiotic use. Babies with gallbladder or liver problems are more prone to Vitamin K deficiency. They have trouble absorbing Vitamin K and other fat-soluble vitamins. However, this condition is extremely rare (1 out of every 60,000 babies), and it has no relationship to adult gallbladder or liver disease. This means that you cannot use a “family history of gallbladder or liver disease” to predict whether or not your baby will have this problem. Also, the first sign of a baby’s gallbladder or liver problem is usually a bleed in the brain or stomach. So most parents don’t know their baby has this very rare problem until the baby starts bleeding.

Oral Vitamin K

There have been no randomized trials that compare weekly or daily oral Vitamin K to the Vitamin K shot. No studies have compared the weekly oral regimen to the 3-dose regimen. The main concern with using oral Vitamin K is that it may not work for infants with undiagnosed gallbladder problems. Like I said above, gallbladder problems in infants are rare (1 out of 60,000) but serious. Babies with gallbladder problems have trouble absorbing fat and fat-soluble vitamins like Vitamin K, so they are at higher risk for late VKDB. Often the first sign of a gallbladder problem is bleeding in the brain or stomach from Vitamin K deficiency. 

Data from some countries suggest the 3-dose regimen of 2 mg oral Vitamin K1 (at birth, one week, and one month) is less effective than the shot, although it’s possible that there is not a significant difference between these two options in their ability to prevent late VKDB. Data shows that both the shot and the 3-dose regimen of 2 mg decreases the incidence of late VKDB to fewer than 1 in 100,000 births. 

The regimen of 2 mg oral Vitamin K1 after birth and then 1 mg orally each week for 3 months has found to decrease the incidence of late VKDB to fewer than 1 in 100,000 births. This oral regimen has been shown to protect infants at higher risk (like those who have undiagnosed gallbladder disease). 

If you choose the oral version of Vitamin K, it is very important that you give your baby ALL the scheduled doses. 

Vitamin K is a fat-soluble vitamin. If it is given on an empty stomach, it may not be absorbed as well. If you give your breastfed baby oral Vitamin K, it is important to give it with a feeding and make sure that it is not spit up. 

You can read more about oral and injectable Vitamin K here!

https://evidencebasedbirth.com/evidence-for-the-vitamin-k-shot-in-newborns/