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Changes in Vitamin K in Human Milk

Baby in diaper laying skin to skin.

The many components of human milk change from hour to hour, day to day, month to month. Let’s take a quick look at the changes in Vitamin K from birth until about 6 months after birth.

What do we know about Vitamin K?

Along with vitamins A, D, and E, Vitamin K is a fat-soluble vitamin. That means it does not dissolve in water. That’s fine, because human milk is a fatty substance.

There are several types of Vitamin K, but the two most important groups related to human milk are:

  • Vitamin K-1 (phylloquinone)
  • Vitamin K-2 (menaquinones)

It is imporant to note that Vitamin K helps blood to clot. Or, otherwise stated, it has an active role in preventing hemorrhaging. That’s especially important for the newborn.

Is Vitamin K in human milk enough for the newborn?

Apparently not.

In a landmark study, Greer showed that the amount of Vitamin K in human colostrum and milk was not enough to meet minimum levels to protect the baby against hemorrhaging. Newer studies since then have confirmed this conclusion.

Admittedly, when studies smack of “mother’s milk is inadequate …” I tend to feel skeptical. I believe evolution teaches us about human needs. My question is, “If the mother’s milk is truly inadequate, then how did the species survive?”

Yet, I have heard of breastfed infants who died of hemorrhage after their parents refused the prophylactic Vitamin K. Worse still, 30 documented cases of death within 18 months were due to hemorrhagic disease here in the US. That included newborns who had received the prophylactic dose of Vitamin K.

Changes in Vitamin K

There is a common belief that the amount of Vitamin K is “highest” shortly after birth. That statement may be true, but let’s look carefully at what that means.

Greer’s study has shown that Vitamin K travels across the placenta rather poorly and Vitamin K levels are low in colostrum.

In a study of 10 mothers, Fournier and colleagues measured concentrations of phylloquinone (Vitamin K-1) in 10 mothers at 3, 8, and 21 days postpartum. They found that concentrations of Vitamin K-1, although low, were higher in colostrum compared to mature milk.

However, Canfield and colleagues found no significant differences in vitamin K levels among a group of 15 mothers at 1, 3 and 6 months. Similarly, Greer and colleagues  found no significant differences at 6 weeks compared to 26 weeks of lactation in a group of 23 women.

Note that Fournier’s study began at the colostral phase and ended at 21 days. But Greer’s study didn’t start until 1 month postpartum. Further, these studies were conducted on small groups.   

What happens after the first 26 weeks (6 months?)? We don’t know.

The word “highest” makes it seem as if the concentrations of Vitamin K are “high” in human milk, which they are not. And there is a documented difference in the first 3 weeks (right around the time when we would say that lactation is “fully established”). However, it seems that the concentration of Vitamin K at approximately1 month is not significantly different than it is at approximately 6 months.  

What are the implications of changes in Vitamin K?

Two fundamental implications come to my mind:

  • What can we tell parents about Vitamin K prophylaxis and deficiency?
  • How would we answer questions on the IBLCE™ Exam?

Until we have strong evidence to the contrary, we should not infer or imply that the need for Vitamin K can be met solely by the mother’s milk.

As for the exam, I would not be surprised if a test item popped up on Vitamin K. If it did, I’d go for the option, “higher concentrations after birth.” Although the levels are relatively low, and there is apparently no difference in concentrations after the mother has mature milk, I think that “higher concentrations after birth” is a reasonable statement.

Have you prepared for possible test questions on the changes of Vitamin K in human milk?

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