Understanding Who Is Most at Risk for Vitamin K Deficiency

October 12, 2025 •

3 min read

Newborn babies are a primary risk group for vitamin K deficiency bleeding (VKDB), with the condition occurring in up to 1.7% of infants who don't receive prophylaxis. This essential fat-soluble vitamin plays a critical role in blood clotting and bone health, and certain populations face a higher risk of not getting or absorbing enough. Understanding who is most at risk for vitamin K deficiency is crucial for both prevention and proper medical care.

Quick Summary

Several groups face a heightened risk of vitamin K deficiency, including newborns due to low placental transfer and intake, people with fat malabsorption disorders, those with liver disease, and individuals on specific long-term medications. These issues compromise the body's ability to absorb or utilize the vital nutrient.

Key Points

Newborns are at high risk: Infants, particularly those exclusively breastfed, are the most susceptible to vitamin K deficiency due to low levels at birth and in breast milk, necessitating routine prophylactic injections.
Malabsorption is a major cause: Conditions like cystic fibrosis, celiac disease, and Crohn's disease impair the absorption of fat-soluble vitamins, leading to vitamin K deficiency.
Liver disease impacts vitamin K function: The liver is crucial for producing clotting factors that depend on vitamin K, so liver disorders increase the risk of bleeding.
Medications interfere with vitamin K: Anticoagulants, long-term antibiotics, and certain antiseizure drugs can disrupt vitamin K metabolism or production, requiring careful monitoring.
Bleeding is the primary symptom: Excessive bleeding and easy bruising are the most common signs of vitamin K deficiency in at-risk individuals.
Prevention is key: For those at risk, prevention often involves medical intervention, such as newborn injections or supplementation, rather than just dietary changes.

Who is Most at Risk for Vitamin K Deficiency?

While vitamin K deficiency is uncommon in healthy adults, certain conditions and life stages significantly increase the risk. A healthy adult's diet typically provides sufficient vitamin K, and intestinal bacteria also produce a form of it (K2). However, this is not the case for everyone. The most vulnerable populations include infants, individuals with chronic health issues affecting nutrient absorption or metabolism, and those taking medications that interfere with the vitamin's function.

Newborns and Infants

Newborns are at the highest risk for vitamin K deficiency bleeding (VKDB). Factors contributing to this include limited transfer of vitamin K from mother to fetus during pregnancy, a lack of gut bacteria at birth to produce vitamin K2, and low levels of vitamin K in breast milk. The American Academy of Pediatrics recommends a vitamin K injection for all newborns to prevent VKDB. Infants whose mothers took certain medications during pregnancy may face an even higher risk.

Individuals with Malabsorption Disorders

Vitamin K is a fat-soluble vitamin requiring dietary fat for absorption. Conditions impairing fat absorption can lead to deficiency. These include cystic fibrosis, which blocks fat-digesting enzymes; celiac disease, which damages the small intestine; Crohn's disease, causing digestive tract inflammation; biliary obstruction or cholestatic liver disease, which impede bile flow necessary for fat absorption; and certain bariatric surgeries that alter the digestive tract.

People with Liver Disease

The liver uses vitamin K to synthesize blood-clotting proteins. Significant liver disease can impair this process, increasing bleeding risk regardless of vitamin K intake. While supplementation can help, failure to improve may indicate severe liver damage.

Individuals Taking Certain Medications

Some medications interfere with vitamin K levels or metabolism. Anticoagulants like warfarin disrupt the vitamin K cycle to prevent clots, requiring consistent vitamin K intake. Long-term broad-spectrum antibiotics can kill gut bacteria producing vitamin K2. Bile acid sequestrants interfere with fat and vitamin K absorption. Certain antiseizure medications can affect vitamin K metabolism, particularly posing a risk to infants exposed in utero.

Comparison of Major Risk Factors for Vitamin K Deficiency


Risk Factor Category	Who is Affected	Mechanism of Deficiency	Key Symptoms
Newborns & Infants	All newborns, especially those breastfed without prophylaxis	Low placental transfer, sterile gut, low vitamin K in breast milk	Bleeding (umbilical cord, circumcision), easy bruising, potential intracranial hemorrhage
Malabsorption Disorders	People with cystic fibrosis, celiac, Crohn's, short bowel syndrome	Impaired fat absorption due to pancreatic insufficiency or intestinal damage	Easy bruising, excessive bleeding from wounds or gums, bloody stools
Liver Disease	Individuals with cirrhosis or biliary obstruction	Decreased synthesis of clotting factors by the impaired liver; reduced bile for absorption	Bruising, oozing from incisions, gastrointestinal bleeding
Medications	Patients on warfarin, long-term antibiotics, certain anticonvulsants	Interference with the vitamin K metabolic cycle or destruction of gut bacteria	Unpredictable bleeding or clotting issues depending on the medication

Prevention and Dietary Recommendations

For most healthy adults, a balanced diet with foods rich in vitamin K1 (from plants) and K2 (from animal products and fermented foods) is sufficient. Good sources include leafy greens, broccoli, Brussels sprouts, soybean and canola oils, natto, eggs, cheese, and chicken. For high-risk individuals, medical intervention like newborn injections or supplementation for those with malabsorption or liver disease is often needed. Individuals on warfarin require careful dietary management under medical supervision.

Conclusion

While rare in healthy adults, vitamin K deficiency risk is elevated in infants, those with malabsorption disorders, liver disease, and individuals on certain medications. Consequences like excessive bleeding can be serious, particularly for newborns. Identifying and managing these risk factors is crucial. A balanced diet helps most, but at-risk individuals often require medical prophylaxis and monitored supplementation. Consult a healthcare provider for diagnosis and management if you suspect a risk of vitamin K deficiency.

For more information on dietary needs, the National Institutes of Health provides comprehensive fact sheets. Source: NIH Office of Dietary Supplements

Frequently Asked Questions

Newborns are especially at risk because they have very low vitamin K stores at birth, a sterile gut that doesn't produce the vitamin, and consume breast milk, which is a poor source. This is why a vitamin K injection is routinely given to prevent serious bleeding.

Yes, long-term use of broad-spectrum antibiotics can disrupt the bacteria in the gut that produce vitamin K2. This can reduce the amount of vitamin K available to the body, especially if dietary intake is also poor.

The liver is essential for both processing vitamin K and producing the blood-clotting proteins that depend on it. Liver disease, such as cirrhosis or cholestasis, impairs these functions, increasing the risk of bleeding.

Medical conditions that cause malabsorption of vitamin K, a fat-soluble vitamin, include cystic fibrosis, celiac disease, Crohn's disease, and biliary obstruction. Any condition that interferes with fat absorption can lead to this deficiency.

In adults, common symptoms include easy bruising, excessive bleeding from cuts or the gums, nosebleeds, and heavy menstrual periods. In more severe cases, it can cause gastrointestinal bleeding.

No, a dietary deficiency of vitamin K is rare in healthy adults. This is because vitamin K is widely available in many foods, particularly leafy greens, and the body's gut bacteria also produce it.

Treatment varies by severity and underlying cause. For newborns, a standard vitamin K injection is given. For adults, a doctor may recommend dietary changes, oral supplements, or injections, especially for those with malabsorption issues.