A ProPublica report published earlier this month indicates that an increasing number of parents are choosing to skip the standard Vitamin K shot for their infants, which has unfortunately led to a rise in babies suffering from severe internal bleeding. This shift has brought Vitamin K into the national conversation, prompting many to ask what this nutrient actually does and why it is so critical during the first few weeks of life.
Simply put, Vitamin K is the essential “key” the body needs to facilitate blood clotting. Without it, the proteins responsible for blood thickening cannot do their job, meaning even a minor bump or a small internal nick can lead to continuous, uncontrolled bleeding. While healthy adults typically maintain plenty of Vitamin K through their diet and the beneficial bacteria in their gut, newborns arrive with very low levels of the nutrient because it does not easily cross the placenta and isn’t present in high amounts in breast milk. Because babies lack these natural reserves, the standard Vitamin K shot administered shortly after birth serves as a vital safety net. Without it, they remain at risk for Vitamin K Deficiency Bleeding, which can occur without any outward warning signs.
What is Vitamin K?
Vitamin K is a fat-soluble vitamin that comes in two main forms, explains PMC. Vitamin K1 (phylloquinone) is found primarily in dark leafy green vegetables. Vitamin K2 (menaquinone) is found in fermented foods, animal products and is also naturally produced by the good bacteria living inside your own gut.
Discovered in 1929, the “K” actually stands for the German word “Koagulation,” meaning coagulation (or clotting). Unlike other vitamins that your body stores in large amounts (like Vitamin D or A), your body stores very little Vitamin K, meaning it is rapidly depleted if you are not constantly replenishing it through your diet or gut bacteria, explains Linus Pauling Institute.
What happens to your body without enough Vitamin K?
To understand a deficiency, you have to look at how a scab forms. When you get a cut, your body initiates a complex “clotting cascade.” Your liver produces several essential proteins called clotting factors. However, these proteins are basically “turned off” when they are first made. Vitamin K acts as the key that activates these clotting factors (specifically prothrombin).
Without enough Vitamin K, the liver still makes the proteins, but they remain inactive. Your blood loses its ability to bind together and form a clot, meaning you will continue to bleed indefinitely from even the smallest internal or external injuries, a NIH publication notes.
Causes of Vitamin K Deficiency
The reasons for a deficiency are wildly different depending on whether you are an adult or a newborn. According to the CDC, all babies are born naturally deficient in Vitamin K. There are three biological reasons for this. Very little Vitamin K passes from the mother through the placenta during pregnancy, breast milk contains extremely low amounts of the vitamin and a newborn’s intestines are completely sterile, meaning they do not yet have the gut bacteria required to manufacture their own Vitamin K2.
Because it is abundant in foods and produced by gut bacteria, adults rarely develop this deficiency solely from a poor diet. Instead, it is usually caused by malabsorption syndromes. Conditions such as celiac disease, Crohn’s disease or cystic fibrosis prevent the intestines from properly absorbing fats. Since Vitamin K is fat-soluble, it is excreted unabsorbed, the Cleveland Clinic explains. Additionally, taking strong, long-term antibiotics can kill off the good bacteria in your gut, temporarily halting your body’s natural production of Vitamin K2.
Health risks and complications
The complications of this deficiency are severe and primarily involve hemorrhage (uncontrolled bleeding).
In infants, the condition is called Vitamin K Deficiency Bleeding (VKDB). This is the exact condition causing the current medical crisis reported in the news. Because newborns have soft skulls, the physical trauma of simply being born can cause minor bleeding in the brain, the CDC reports. Without Vitamin K to stop it, this minor bleed turns into a massive, catastrophic brain hemorrhage that can cause permanent brain damage, severe disability or death within the first few weeks of life.
In adults, prolonged deficiency leads to frequent nosebleeds, deep muscle hematomas (bruises) and gastrointestinal bleeding. Furthermore, because Vitamin K also helps bind calcium to your bones, long-term deficiency dramatically increases your risk of developing osteoporosis and suffering bone fractures.
What to do about Vitamin K Deficiency
Treatment is highly effective and fast, relying on the direct replacement of the missing vitamin. For newborns, as explained by a PMC publication, the universal medical standard is a single, prophylactic intramuscular injection of Vitamin K administered within the first few hours after birth. This one shot provides a slow-release depot of the vitamin that protects the baby completely until their gut bacteria develop and they start eating solid foods.
For adults with a deficiency due to malabsorption or medication interactions, doctors will prescribe oral Vitamin K supplements (phytonadione) or, in cases of severe bleeding emergencies, administer the vitamin intravenously alongside plasma transfusions to restore clotting factors immediately.
Dr. Justus Rabach, MD, explains, “If you are trying to boost your Vitamin K levels naturally through diet, eating a giant bowl of dry spinach is not the most efficient method. Because Vitamin K is a fat-soluble vitamin, your intestines need dietary fat to pull it into your bloodstream. Always pair your leafy greens with a healthy fat, such as a drizzle of olive oil, sliced avocado or a handful of nuts, to maximize your body’s ability to absorb nutrients.”
When to see a doctor
While adults rarely need to worry about this, you should be vigilant for signs of abnormal bleeding. You need to see a doctor immediately if you experience sudden, unexplained and massive bruising, if you notice dark, tarry blood in your stool, or if you have gums that bleed heavily and refuse to stop.
For parents of newborns, seek emergency medical care immediately if your baby (who did not receive the birth shot) develops bruising around their head or face, pale skin, yellowing of the eyes or begins oozing blood from their umbilical cord stump, as these are critical signs of late-onset VKDB.
“Vitamin K is important for helping the blood clot and preventing dangerous bleeding in babies, like bleeding into the brain,” said Dr. Kristan Scott, MD, of the Children’s Hospital of Philadelphia.
Who is most at risk?
Newborn infants whose parents decline the prophylactic birth injection are at the absolute highest risk of fatal deficiency. They are born with naturally low levels of the vitamin because it does not cross the placenta efficiently, and breast milk is typically a poor source of the nutrient. Without the standard prophylactic Vitamin K injection at birth, these infants are at an extremely high risk for Vitamin K Deficiency Bleeding (VKDB).
Beyond the neonatal stage, conditions such as Crohn’s disease, Celiac disease, cystic fibrosis and primary biliary cholangitis disrupt the body’s ability to process fats, effectively starving the body of Vitamin K even if the person’s diet is technically adequate.
Which foods are rich in Vitamin K?
The most concentrated dietary sources of Vitamin K1 (phylloquinone) are found within the plant kingdom, specifically among dark leafy green vegetables. Kale is widely considered the gold standard in this category, offering several times the daily recommended intake in a single serving. Other exceptional sources include collard greens, spinach, Swiss chard, turnip greens and beet greens. Beyond the leafy varieties, cruciferous vegetables such as broccoli, Brussels sprouts and cabbage provide significant amounts of the nutrient.
The absolute powerhouse of Vitamin K2 is natto, a traditional Japanese dish made from fermented soybeans; it contains a higher concentration of the vitamin than almost any other food on the planet. For those who may not enjoy the pungent profile of natto, smaller but meaningful amounts of K2 can be found in fermented cheeses like Gouda, Edam and Jarlsberg, as well as in fatty meats and egg yolks.
Bottom line
Vitamin K deficiency is a rare but highly dangerous condition that prevents the blood from clotting, currently making tragic headlines due to a rise in life-threatening newborn bleeds tied to medical misinformation. While adults can usually maintain healthy levels through eating leafy greens and producing gut bacteria, newborns are biologically born without it and desperately need a prophylactic shot at birth to prevent fatal brain hemorrhages. Understanding the critical role this vitamin plays in your circulatory system is the key to preventing devastating, uncontrolled bleeding.
Frequently Asked Questions
What diseases can Vitamin K prevent?
Vitamin K primarily prevents Vitamin K Deficiency Bleeding (VKDB) in newborns and, in adults, helps lower the risk of severe osteoporosis and may reduce cardiovascular calcification.
How can I increase my Vitamin K?
You can quickly and easily increase your Vitamin K levels by incorporating more dark leafy green vegetables into your meals and pairing them with a healthy fat, such as olive oil, to maximize intestinal absorption.
Citations
Clark A. More Parents Are Declining Vitamin K Shots for Their Newborns. ProPublica. Published May 9, 2024. https://www.propublica.org/article/more-parents-decline-vitamin-k-shot-newborns
Mladěnka P, Macáková K, Kujovská Krčmová L, et al. Vitamin K – sources, physiological role, kinetics, deficiency, detection, therapeutic use, and toxicity. Nutrition Reviews. 2021;80(4). doi:https://doi.org/10.1093/nutrit/nuab061
Linus Pauling Institute. Vitamin K. Linus Pauling Institute. Published August 5, 2019. https://lpi.oregonstate.edu/mic/vitamins/vitamin-K
Eden RE, Coviello JM, Daley SF. Vitamin K deficiency. Nih.gov. Published September 8, 2023. https://www.ncbi.nlm.nih.gov/books/NBK536983/
CDC. Frequently Asked Questions About Vitamin K Deficiency Bleeding. Vitamin K Deficiency Bleeding. Published May 22, 2024. https://www.cdc.gov/vitamin-k-deficiency/faq/index.html
Cleveland Clinic. Malabsorption . Cleveland Clinic. Published April 6, 2022. https://my.clevelandclinic.org/health/diseases/22722-malabsorption
CDC. About Vitamin K Deficiency Bleeding. Vitamin K Deficiency Bleeding. Published May 22, 2024. https://www.cdc.gov/vitamin-k-deficiency/about/index.html
Ng E, Loewy AD. Guidelines for vitamin K prophylaxis in newborns. Paediatrics & Child Health. 2018;23(6):394-397. doi:https://doi.org/10.1093/pch/pxy082