What Causes a Vitamin K Deficiency? Understanding the Root Factors

December 18, 2025 •

2 min read

While vitamin K deficiency is rare in healthy adults, it is a significant concern for newborns and individuals with certain health conditions. Understanding the underlying causes is crucial for prevention, especially considering the vitamin's vital role in blood clotting and bone health.

Quick Summary

Low vitamin K levels result from dietary deficiencies, fat malabsorption disorders, specific medication use, liver disease, and newborns' low stores and underdeveloped gut bacteria.

Key Points

Newborn Susceptibility: Infants are born with very low vitamin K reserves, a sterile gut, and receive limited vitamin K from breast milk, making them uniquely vulnerable to deficiency.
Malabsorption Issues: Chronic gastrointestinal or liver conditions such as celiac disease, cystic fibrosis, and biliary diseases significantly impair the body's ability to absorb the fat-soluble vitamin K.
Medication Interference: Specific drugs, including blood thinners like warfarin and prolonged courses of broad-spectrum antibiotics, can disrupt vitamin K metabolism or destroy its producing gut bacteria.
Dietary Insufficiency: While uncommon in healthy adults, diets lacking in leafy greens or very low-fat diets can contribute to low vitamin K levels over time.
Underlying Health Conditions: Liver disease is a major factor, as the liver produces bile vital for absorption and is where vitamin K-dependent clotting factors are synthesized.

Vitamin K is a fat-soluble vitamin essential for producing proteins needed for blood clotting, bone metabolism, and heart health. It's sourced from vitamin K1 (plants) and vitamin K2 (gut bacteria). Deficiency occurs with issues in intake, absorption, production, or utilization, though the body can recycle its supply.

Dietary and Nutritional Causes

Dietary deficiency is uncommon in healthy adults due to vitamin K's presence in many foods. However, certain diets contribute:

Low Rich Food Intake: Diets low in leafy greens like spinach and kale can mean insufficient vitamin K1.
Very Low-Fat Diets: As vitamin K is fat-soluble, fat is needed for absorption. Very low-fat diets hinder this.
Malnutrition/Alcoholism: Depletes nutrients, including vitamin K, often with poor diet and liver issues.
TPN: Long-term IV feeding without vitamin K increases risk.

Medical Conditions Affecting Absorption

Conditions hindering fat absorption are major causes, as fat is needed for vitamin K uptake.

Celiac Disease: Damages the small intestine, impairing nutrient absorption.
Cystic Fibrosis: Blocks pancreatic enzymes needed for fat digestion.
Crohn's Disease/IBD: Chronic inflammation affects absorption.
Liver/Biliary Tract Diseases: Reduce bile needed for fat and vitamin K absorption. Conditions like chronic cholestasis or blocked bile ducts are included.
Intestine Removal: Reduces surface area for absorption.

Medication-Induced Deficiency

Some medications interfere with vitamin K:

Anticoagulants: Warfarin blocks vitamin K's role in clotting factor activation. Patients need careful monitoring.
Antibiotics: Long-term use can kill gut bacteria producing vitamin K2.
Bile Acid Sequestrants: Can interfere with absorption of fat-soluble vitamins.
Anti-Seizure Medications: Some, like phenytoin, can affect vitamin K metabolism.

The Unique Risk for Newborns

Newborns are highly susceptible to Vitamin K Deficiency Bleeding (VKDB) due to:

Limited Placental Transfer: Low initial stores from the mother.
Sterile Gut: Lack of bacteria to produce vitamin K2.
Low Breast Milk Vitamin K: Exclusively breastfed infants are more vulnerable than formula-fed ones.
Maternal Medication: Increases risk of early VKDB if taken during pregnancy.

Comparing Causes: Adults vs. Newborns


Cause	Adults	Newborns
Primary Reason	Underlying medical conditions or medication use	Physiologically low stores and production
Dietary Contribution	Inadequate intake or very low-fat diet	Low vitamin K content in breast milk
Gut Flora	Disrupted by long-term broad-spectrum antibiotics	Intestines are not yet colonized with vitamin K-producing bacteria
Malabsorption	Underlying diseases (Celiac, Crohn's, CF)	Liver disease, CF, chronic diarrhea
Medications	Anticoagulants (warfarin), antibiotics	Certain maternal medications passed to fetus

Conclusion

Vitamin K deficiency in healthy adults is rare, more often stemming from diet, gut health, or medications. Infants face high risk due to their undeveloped systems. Understanding causes like malabsorption, medication effects, and newborn vulnerabilities allows for targeted prevention and management, including addressing underlying conditions, medication review, and ensuring adequate intake. A routine vitamin K injection is key for newborns to prevent VKDB.

For more detailed information, consult the CDC's resources on Vitamin K Deficiency Bleeding.

Frequently Asked Questions

Newborns have limited vitamin K stores from the placenta, a sterile gut that doesn't produce the vitamin, and receive low amounts from breast milk. This puts them at a high risk for Vitamin K Deficiency Bleeding (VKDB).

Yes, long-term use of broad-spectrum antibiotics can kill the beneficial gut bacteria that produce vitamin K2, potentially leading to a deficiency.

The liver plays a key role in vitamin K metabolism and produces bile needed for its absorption. Liver diseases or conditions that block bile ducts disrupt these processes, causing a deficiency.

As a fat-soluble vitamin, vitamin K requires the presence of dietary fat to be properly absorbed by the intestines. A very low-fat diet can inhibit this absorption, even if vitamin K intake is adequate.

Conditions like celiac disease, cystic fibrosis, Crohn's disease, and other inflammatory bowel diseases can damage the intestine or block fat digestion, leading to poor vitamin K absorption.

Yes. Beyond warfarin, certain medications like some anti-seizure drugs and bile acid sequestrants can interfere with vitamin K metabolism or absorption.

The main symptoms are related to impaired blood clotting and include easy bruising, excessive bleeding from cuts or wounds, nosebleeds, and blood in the urine or stool.