Vitamin K Functions, Deficiency, Dietary Sources, and Interactions

Vitamin K is an essential nutrient that plays a crucial role in various bodily functions. In this article, we will explore the functions of vitamin K, the risk factors for deficiency, the signs and symptoms of deficiency, dietary sources of vitamin K, and potential interactions with medications.

What Does Vitamin K Do and Its Role in the Body?

Vitamin K, a fat-soluble vitamin, is vital for proper coagulation or blood clotting. The term “vitamin K” originates from the German word “coagulation,” emphasizing its role in preventing hemorrhages. Newborn babies are at a higher risk of vitamin K deficiency, which is why they receive a vitamin K injection shortly after birth. Additionally, vitamin K is necessary for the production of various proteins and substances that contribute to coagulation and maintain normal calcium levels in the body.

Who is at Risk for a Vitamin K Deficiency?

While vitamin K deficiency is considered rare, certain individuals are more prone to it. Those with a low intake of vitamin K in their diet, malabsorption issues, alcohol abuse, general malnutrition, liver or biliary diseases, celiac disease, cystic fibrosis, and those on long-term antibiotics, hemodialysis, or suffering from severe burns are at a higher risk.

Signs and Symptoms of a Vitamin K Deficiency

Although vitamin K deficiency is rare, it can manifest in various ways. Prolonged prothrombin time, unusual bleeding, easy bruising, frequent gum bleeding, osteopenia, and osteoporosis are potential signs of vitamin K deficiency. While these symptoms can be caused by other factors, they may indicate a deficiency and warrant further investigation.

Dietary Sources of Vitamin K

To maintain adequate vitamin K levels, it’s important to incorporate dietary sources rich in this nutrient. Vitamin K1, primarily found in plants, can be obtained from foods like broccoli, kale, spinach, asparagus, dark green lettuce, beef liver, green tea, and turnip greens. Fermented foods, meats, and cheeses contain vitamin K2. Soybean and canola oil, fortified meal replacement shakes, and natto (fermented soybean) are also sources of vitamin K.

Can Vitamin K Supplements Interact with Medications?

Vitamin K supplementation can interact with certain medications. Oral anticoagulants like Warfarin can be affected by excess vitamin K intake from the diet. Therefore, it’s crucial to consult a healthcare provider before making any adjustments. Other medications such as cephalosporins (antibiotics), phenytoin (Dilantin), and orlistat (Xenical) can also interact with vitamin K, potentially leading to deficiencies or reduced absorption.


Vitamin K plays a vital role in coagulation, bone health, and other physiological functions. While deficiency is rare, it can occur in individuals with specific risk factors or medical conditions. Incorporating vitamin K-rich foods into your diet, along with consulting a healthcare provider about potential interactions with medications, can help maintain optimal vitamin K levels. By staying informed and taking necessary precautions, you can ensure the benefits of vitamin K for your overall health and well-being.