How common is vitamin K deficiency? A deep dive into prevalence and prevention

October 29, 2025 •

4 min read

While severe vitamin K deficiency is considered rare in healthy adults, certain populations face a significantly higher risk, and it is a notable concern in newborns. This essential fat-soluble vitamin plays a critical role in blood clotting and bone health, making its deficiency a serious health matter.

Quick Summary

Vitamin K deficiency is uncommon in healthy adults but affects high-risk individuals with certain medical conditions or on specific medications. Newborns are particularly vulnerable, so prophylactic injections are standard practice. Symptoms include easy bruising and bleeding, while severe cases can lead to serious hemorrhage. Timely diagnosis and treatment are essential.

Key Points

Infants at High Risk: Vitamin K deficiency is much more common in newborns, leading to Vitamin K Deficiency Bleeding (VKDB), and a prophylactic injection at birth is standard practice to prevent it.
Rare in Healthy Adults: Severe vitamin K deficiency is rare in healthy adults who eat a balanced diet, as gut bacteria also produce some of the vitamin.
Underlying Conditions: In adults, deficiency is most often caused by medical conditions like fat malabsorption disorders, liver disease, or prolonged antibiotic use.
Medication Interference: Anticoagulants like warfarin intentionally interfere with vitamin K, requiring careful dietary management and monitoring.
Bleeding Is a Key Symptom: Excessive bleeding and easy bruising are the primary signs of a deficiency, with severe cases leading to potentially fatal hemorrhage, especially in infants.
Diagnosed with Blood Tests: Deficiency can be diagnosed with blood tests such as prothrombin time (PT) and by measuring specific protein levels (PIVKA-II).
Dietary Prevention for Adults: A diet rich in leafy green vegetables, vegetable oils, and fermented foods is the main way healthy adults prevent a deficiency.

Understanding the Prevalence of Vitamin K Deficiency

For most healthy adults, vitamin K deficiency is not common. A balanced diet, along with the vitamin K produced by gut bacteria, is usually sufficient. However, specific groups are at higher risk. While subclinical deficiency may occur in a small percentage of healthy adults, significant bleeding is typically seen in those with underlying medical conditions. Infants, especially newborns, are highly susceptible to deficiency, which can lead to Vitamin K Deficiency Bleeding (VKDB).

Vitamin K Deficiency in Infants

Infants are born with low vitamin K stores as little crosses the placenta. They also lack the gut bacteria needed to produce vitamin K2. This makes them vulnerable to VKDB.

VKDB prevalence depends on the type and whether a prophylactic injection is given:

Early and classical VKDB: Occurs in the first week, with higher rates if mothers took certain medications during pregnancy.
Late VKDB: Affects infants 2 weeks to 6 months old, especially exclusively breastfed babies not receiving a vitamin K injection at birth. Prophylactic injection significantly reduces this risk.

Causes and Risk Factors for Deficiency

In adults, deficiency is usually due to underlying health issues or medical treatments affecting absorption or metabolism, rather than just diet.

Conditions that increase risk:

Malabsorption syndromes: Conditions like cystic fibrosis, celiac disease, and Crohn's disease hinder fat-soluble vitamin absorption, including vitamin K.
Liver disease: Severe liver disease impairs the production of vitamin K-dependent clotting factors.
Biliary obstruction: Blocks bile ducts, preventing bile salts needed for vitamin K absorption.
Chronic illness and poor nutrition: Critically ill or malnourished individuals may have insufficient intake and poor absorption.

Medications that interfere with vitamin K:

Anticoagulants (e.g., warfarin): These medications block vitamin K action to prevent clots. Vitamin K intake needs careful monitoring.
Long-term antibiotics: Can kill gut bacteria that produce vitamin K2.
Cholesterol-lowering drugs: May interfere with fat-soluble vitamin absorption.

Symptoms and Diagnosis

Symptoms often relate to impaired blood clotting, primarily excessive bleeding and easy bruising.

Common symptoms in adults:

Easy bruising or small clots under nails.
Excessive bleeding from cuts, wounds, or surgery.
Nosebleeds or bleeding gums.
Blood in urine or dark, tarry stool.
Heavy menstrual periods.

Common symptoms in newborns:

Bleeding from the umbilical cord stump.
Bruising on the head or face.
Nose or gastrointestinal bleeding.
Life-threatening brain hemorrhage in severe cases.

Diagnosis typically involves blood tests measuring clotting time, such as prothrombin time (PT) and INR. PTT may also be prolonged in severe cases. PIVKA-II levels can detect subclinical deficiency.

Prevention and Treatment

Prevention

A balanced diet is key for adults. However, the most vital prevention is a vitamin K injection for all newborns shortly after birth, which is highly effective against VKDB.

Treatment

Treatment involves vitamin K administration, with the method depending on severity and cause.

Oral vitamin K: Used for non-emergency correction in adults, but absorption can be variable with malabsorption.
Intramuscular or subcutaneous injection: Preferred for severe cases or poor oral absorption. This is standard for neonatal prophylaxis.
Intravenous (IV) vitamin K: For life-threatening bleeding; administered slowly under medical supervision.

Comparison of Vitamin K Deficiency in Adults vs. Infants


Feature	Adults	Infants
Overall Prevalence	Rare in healthy individuals	Common in newborns without prophylaxis
Primary Cause	Underlying medical issues or medications	Inadequate placental transfer and low stores at birth
Risk Factors	Malabsorption, liver disease, anticoagulants, long-term antibiotics	Exclusively breastfed without injection, maternal medication use
Key Symptoms	Easy bruising, mucosal bleeding, dark stool	Bleeding from umbilical cord, circumcision, or GI tract
Severe Complication	Severe hemorrhage, potential for complications	Intracranial hemorrhage, potentially fatal
Standard Prevention	Balanced diet rich in vitamin K foods	Prophylactic injection at birth

Dietary Sources of Vitamin K

A nutritious diet is crucial for adult prevention. Vitamin K1 (phylloquinone) and K2 (menaquinones) are the main forms in food.

Rich sources of Vitamin K1 include:

Kale and spinach
Collard and turnip greens
Broccoli and Brussels sprouts
Lettuce
Parsley
Green peas
Soybean and canola oils

Good sources of Vitamin K2 include:

Natto (fermented soybeans)
Some fermented foods, cheeses, and yogurts
Egg yolks and certain animal products

Consuming vitamin K with fat can improve absorption. More information on dietary sources is available from the NIH Office of Dietary Supplements: NIH Office of Dietary Supplements - Vitamin K Fact Sheet.

Conclusion

Vitamin K deficiency is uncommon in healthy adults but is a significant risk for newborns and those with specific medical conditions. Causes include malabsorption, liver disease, and certain medications. Symptoms, primarily bleeding, vary in severity. Prevention includes routine vitamin K injections for newborns and a diet rich in vitamin K foods for adults. Early diagnosis and treatment are vital to prevent serious complications.

Frequently Asked Questions

No, severe vitamin K deficiency is rare in healthy adults. This is because vitamin K is widely available in many foods, and bacteria in the intestine also produce some of the vitamin.

Newborns are at higher risk because they have low vitamin K stores at birth, very little passes from mother to fetus during pregnancy, their guts lack the necessary bacteria to produce it, and breast milk provides only small amounts.

The main symptom is excessive bleeding. This can manifest as easy bruising, blood in the urine or stool, nosebleeds, gum bleeding, and heavy menstrual periods in women.

A doctor can diagnose vitamin K deficiency with blood tests that measure the time it takes for blood to clot, such as prothrombin time (PT) and the International Normalized Ratio (INR). They may also check levels of PIVKA-II, a marker for deficiency.

Conditions that cause fat malabsorption, such as cystic fibrosis, celiac disease, and chronic pancreatitis, are major risk factors. Liver disease and disorders affecting the bile ducts also increase risk.

Excellent sources of vitamin K include green leafy vegetables like kale, spinach, and broccoli. Other sources include soybean oil, canola oil, and fermented foods like natto.

Treatment involves administering vitamin K supplements, either orally or via injection, depending on the severity and underlying cause. In severe cases, intravenous administration may be necessary.

Yes, some medications can interfere with vitamin K. For example, anticoagulants like warfarin block its activity, while long-term antibiotic use can reduce the gut bacteria that produce it.