What About Vitamin K?
Let’s take a look at the facts about vitamin K.
Vitamin K is an essential vitamin. It is one that we need to get from our diet, and it plays a major role in blood clotting. Although our guts can synthesize vitamin K in small amounts (primarily the bacteria known as bacteroides), we can’t make more than about 10% of what we need — and that’s assuming our gut flora is healthy. Over 90% of what we need must come from food like leafy greens (K1) or natto, or specific hard cheese like gouda or Romano (K2). K1 is water soluble and K2 is fat-soluble. There are also synthetic forms, known as K3, K4, and K5.
Without enough vitamin K, people are at risk for internal or external bleeding, which can be uncontrolled and lead to serious consequences or even death. With too much vitamin K, we could end up with blood clots that could cause strokes or other serious consequences. Like most things, our bodies need to maintain a steady amount — neither too much nor too little. It doesn’t take much though, for blood to clot properly. The RDA for adults is 120 mcg for men and 90 mcg for women.
So we know that vitamin K is necessary, and that there are definite risks to having too little. Let’s look now at the issue with newborns.
Newborns and Vitamin K: The Normal Experience
The media would have you believe that parents are refusing the vitamin K shot because they think it’s a vaccine (it’s not) or that they just want to keep their perfect little baby “natural.” Of course, it’s much more complicated than that.
When I began this research, I believed what I had read: that vitamin K doesn’t cross the placenta, that all newborns are deficient, and that levels rebound within 8 days.
But it turns out the evidence doesn’t really support any of that.
After finding a whole lot of assumptions in the recent studies (from the last 10 years) with no data explaining how they were arrived upon, I looked back at studies from the 80s, hoping to find the ones that led to what we believe today and what informs the clinical practice of giving vitamin K shots to all babies. What are ‘typical’ newborn levels? What studies were used to find that, how large were they, how healthy were the mothers and babies?
The studies that the “low vitamin K levels” were based on (that I found) tended to be fairly small (fewer than 40 mother-baby pairs) and many looked at the levels found in cord blood rather than the baby directly. And their results varied quite widely.
Some found that vitamin K doesn’t cross the placenta at all. Some found that it does cross the placenta, but only under certain circumstances — it doesn’t happen readily. It may happen if a mother supplements with vitamin K during pregnancy, especially in the final days before birth (it seems to only happen when mothers have high levels). In fact, mothers who consumed natto during their pregnancy (which is rich in vit K2, MK-7) had placentas with much higher levels of vitamin K than mothers who didn’t supplement.
The newborns in the studies did tend to have low levels of vitamin K, which ranged from 0.2 – 1.18 ng/mL. And most interestingly, whereas we’ve been told that levels rebound to “normal adult levels” by about 8 days of life, they actually do not (they do rise for the first 10 days, and then begin dropping again later). In one study, levels dropped after the first month, reaching the lowest level around 6 weeks of age, and stayed down for the first six months of life (with exclusive breastfeeding). The average level in the first six months of life was 0.2 – 0.24 ng/mL, about half of the average adult level.
According to another study, even though the vitamin K levels of breastfed babies were significantly lower than formula-fed babies, the important coagulation factors were not lower!
So we know from this information that a lot of what we have been told about vitamin K isn’t true.
- Vitamin K can cross the placenta, but only under very limited circumstances
- Supplementing vitamin K during pregnancy can raise the newborn’s stores somewhat (but not in all cases)
- Levels of vit K remain low in exclusively breastfed infants until the introduction of complementary foods/formula (but this doesn’t pose a problem and isn’t considered deficiency)
- Supplementing vitamin K while breastfeeding can raise levels (but this usually isn’t necessary)
This leads us to believe that for the vast majority of babies, vitamin K supplementation is not necessary.
So why do some babies experience problems?
Why Vitamin K Deficiency Bleeding Occurs
We all know that, unfortunately, not all babies are healthy and that some do experience vitamin K deficiency bleeding (VKDB). VKDB is broken down into three categories: early, classic, and late.
Early VKDB is typically (almost always) found in babies whose mothers are on some kind of drug that lowers vitamin K levels, and it presents within 24 hours of birth. If your baby is at risk for this, you will know.
Classic VKDB is often related to delayed or insufficient feeding, and presents within 24 hours to 7 days after birth. It is typically mild (bruising, some bleeding) but can become more serious in some cases.
Late VKDB is very rare, but very serious. The incidence is around 1 in 15,000 in babies who don’t receive a vitamin K shot, and babies who have liver problems or gut malabsorption issues are at greater risk. This is seen almost exclusively in breastfed babies, because formula has vitamin K in it. About 20% of babies who end up with late-onset VKDB die, and many have neurological damage.
So, obviously, this is serious. But we have to ask — why breastfed babies?
Levels of vitamin K are sharply lower in breastmilk than formula — but we covered above why, for most babies, that isn’t an issue. Why is it an issue for some? What is causing this to occur?
We know that the babies with liver issues and gut malabsorption are at greater risk, which tells us that clearly something is wrong, and that is leading to this problem. Vitamin K is largely stored in the liver, so if there is liver damage or an immature liver, levels will be lower and this could be a risk factor.
The other major issue is gut health.
An infant’s gut flora is needed to synthesize vitamin K, and also break down and absorb what is in their diet. If they do not have healthy gut flora — or rather, if mom doesn’t — then they will not get adequate vitamin K. There is not a lot of evidence in this area yet, but there is some evidence that poor colonization can lead to low vitamin K levels. Of course, breastfed infants will naturally have low vitamin K levels because their gut flora is primarily lactobacillus and bifidobacteria, which don’t synthesize vitamin K. Formula-fed babies will have high levels because of fortification of formula and because formula produces different gut flora, including bacteroides, which do synthesize vitamin K.
(But we need to recognize that exclusive breastfeeding is the biological norm and that breastfed babies actually have “normal levels” in most cases, while formula-fed babies have “high levels.”)
I believe there is enough evidence to show that babies who have late-onset VKDB are unhealthy, and have specific risk factors that can and should be identified, and treated. That is, the underlying causes should be treated — not the vitamin K levels specifically.
Article continued on Modern Alternative Mama http://www.modernalternativemama.com/2014/09/25/baby-need-vitamin-k-shot/