Someone sent me a sad link to a coroner’s report about a baby in Australia who died from bleeding due to late onset vitamin K deficiency. It’s an older case (2011), but I decided to do some research to see if this was something I needed to write about. Above the fold I found this from the Healthy Home Economist.
The “Healthy” Home Economist hits it out of the park when it comes to flagrant misunderstanding of medicine and biochemistry, but that’s not exactly new on the Internet. What caught my eye was the > 21k shares on Facebook, because if 21,000 pregnant women followed her advice to skip the vitamin K shot 1-2 babies will have potentially devastating bleeding.
Let’s start at the beginning and use science.
What is Vitamin K?
Among other things vitamin K helps blood to clot. Without it we can have catastrophic bleeding, even with no trauma. We don’t need very much of it (that why an adult has to be severely malnourished to have issues with vitamin K deficiency related blood clotting), but we need some.
There are 2 types of vitamin K: K1 or phylloquinone and K2 or menaquinone. Vitamin K1 comes from our diet (leafy green vegetables, cauliflower, turnip, and Brussels sprouts, avocado, banana, kiwi, and soybean oil). Vitamin K2 is primarily made by intestinal bacteria, like Bacteroides, but some may also come from diet (meats, eggs, and fermented cheeses).
Why is low vitamin K an issue in newborns?
Babies don’t have great stores at birth because vitamin K1 doesn’t cross the placenta very well. In addition, the newborn gut isn’t colonized sufficiently with the right bacteria to produce vitamin K2. The only source for a baby is food, but breast milk is very low in vitamin K so newborns can become vitamin K deficient. There 3 types:
- Early onset, within 24 hours when a pregnant woman was taking drugs that block vitamin K so her baby receives essentially none during pregnancy.
- Classical, onset 24 hours to 7 days. Often related to poor feeding. This happens in less than 0.5% of babies. Severe bleeding into the brain is less common, but other bleeding complications do occur.
- Late, 2-12 weeks. Seen in exclusively breastfed infants (formula is fortified with vitamin K). While the incidence in exclusively breastfed infants is relatively low (1/10,000 to 1 in 20,000) it is very high consequence – 50% will have brain bleeding and brain injury is not an uncommon outcome for the survivors and 20% will die.
We know from many good studies that giving a vitamin K shot at birth reduces the risk of bleeding due to vitamin K deficiency to essentially zero. The standard dose for a term baby is 1 mg. This is obviously much higher than the daily requirement because it is meant to boost the stores and carry a baby through the first 3-6 months. Oral vitamin K can be given, but has some drawbacks one being the cost and the other that it doesn’t seem to work as well as the shot.
Is this really an issue? I mean we evolved to be exclusively breastfed!
The catastrophic bleeding is well described (read through the coroner’s report if you want to know what actually happens).
A newborn appears to have several protective mechanisms against vitamin K deficiency induced bleeding, but obviously for 1/10,000-20,000 or so that doesn’t work. Why some babies get Vitamin K deficiency bleeding and others don’t is a bit like asking why some people get cancer and some people don’t.
Well, 1/10,000-20,000 doesn’t seem like it’s a lot…
The risk of a serious car accident driving home from the hospital is probably less than the risk of bleeding due to vitamin K, yet what parent wouldn’t put their newborn in a carseat on the ride home? A car accident, like vitamin K deficiency induced bleeding, is low probably but very high consequence for a newborn. This number translates to 100-200 babies who would be affected every year in the United States if no vitamin K were given.
Are vitamin K shots safe?
There was a previous concern raised many years ago (in the 1990s) in a small study (lower quality) about an potential association with an increased risk of leukemia, however 2 large retrospective studies and 6 case control studies show no increased risk. Proving a negative is very, very hard but there is no good data to support an association between leukemia and vitamin K shots. There is one case in the world literature of a baby dying from anaphylaxis (serious allergic reaction) to a vitamin K shot.
Isn’t the vitamin K shot synthetic and not real vitamin K?
The vitamin K1 newborns receive isn’t some Frankenstein vitamin K-like chemical, it is vitamin K1. If it were not it couldn’t be called vitamin K1. Phylloquinone is used for the natural form of vitamin K1 and the synthetic is called phytonadione. Making a vitamin in a lab doesn’t make it dangerous, it makes it bioindentical.
What about eating more vitamin K in pregnancy?
It doesn’t cross the placenta well so the baby doesn’t get it.
Now let’s compare what the “Healthy” Home Economist has to say versus science…
There is nothing “healthy” about encouraging parents to play roulette with their babies. There are many documented cases of severe bleeding due to parental refusal of vitamin K and what a generation of pediatricians had never seen is now returning.
The “Healthy” Home Economist is dangerously misinformed about vitamin K and her advice is potentially deadly.
Chemical structure of phytonadione, also known as Phylloquinone; VITAMIN K1; 2-Methyl-3-phytyl-1,4-naphthoquinone