Are Vegetarians Deficient in Vitamin K? A Look at Plant-Based Sources

January 13, 2026 •

4 min read

According to the National Institutes of Health, clinically significant vitamin K deficiency is rare in healthy adults. Despite this, many wonder: Are vegetarians deficient in vitamin K? The truth is, a balanced plant-based diet can easily meet and often exceed daily requirements, especially when focusing on diverse food sources.

Quick Summary

Vegetarians generally get ample vitamin K1 from greens and oils. K2 can be obtained from fermented foods, while gut bacteria also produce some, making true deficiency uncommon.

Key Points

Rare Deficiency: Clinically significant vitamin K deficiency is uncommon in healthy adults, including vegetarians, who consume a balanced diet.
Two Forms: Vitamin K exists as K1 (phylloquinone) from plants and K2 (menaquinone) from fermented foods and gut bacteria.
Rich Plant Sources: Vegetarian diets are naturally rich in vitamin K1 from dark leafy greens like kale and spinach, as well as vegetables like broccoli.
Obtaining K2: Vegetarians can get vitamin K2 from fermented foods such as natto and sauerkraut, and through gut bacteria converting some K1.
Maximize Absorption: Because it's fat-soluble, vitamin K absorption is enhanced by eating K-rich foods with a source of healthy fat, like oil or avocado.
Medical Causes: Risk factors for true deficiency usually involve underlying medical conditions or medication, not simply a vegetarian diet.

Understanding Vitamin K: The Difference Between K1 and K2

Vitamin K is a crucial, fat-soluble vitamin involved in blood clotting and bone health. It primarily exists in two forms: phylloquinone (K1) and menaquinone (K2). Understanding their sources and functions is key to assessing vegetarian intake.

Vitamin K1 (Phylloquinone): This is the primary dietary form of vitamin K and is found abundantly in plant-based foods. Dark, leafy green vegetables are particularly rich sources.
Vitamin K2 (Menaquinone): This form is produced by bacteria and is found in fermented foods, as well as some animal products. The bacteria in our own intestines also produce a certain amount of K2.

Because K1 is so plentiful in the plant kingdom, it's often the main form of vitamin K in Western diets. For vegetarians, the focus shifts to ensuring a consistent intake of K1 while incorporating fermented foods for K2.

Why Most Vegetarians Don't Need to Worry

Given the rich sources of K1 readily available in a plant-based diet, most vegetarians are not at risk for deficiency. A varied diet that includes plenty of vegetables and plant-based oils provides a robust intake of this essential vitamin. Furthermore, the body has a storage system in the liver for vitamin K, so a daily intake is not always necessary for meeting overall needs.

Vegetarian Sources of Vitamin K

Here is a list of excellent vitamin K sources for vegetarians:

Dark Leafy Greens: Kale, spinach, collard greens, turnip greens, and Swiss chard are some of the most potent sources of K1.
Cruciferous Vegetables: Broccoli, Brussels sprouts, and cabbage also contribute significant amounts of K1.
Vegetable Oils: Oils like soybean, canola, and olive oil contain vitamin K. Cooking with these fats can also improve absorption.
Fermented Foods: Natto (fermented soybeans) is an exceptionally high source of K2. Sauerkraut and certain plant-based kefirs also contain K2.
Legumes: Soybeans and edamame are good sources.
Fruits: Blueberries, figs, and pomegranate offer smaller but still beneficial amounts.

The Role of Gut Bacteria in Vitamin K Production

Our intestinal bacteria play a significant role in producing vitamin K2. While this production alone may not be sufficient, a healthy gut microbiome can contribute to overall vitamin K status. This is one reason why consuming fermented foods and maintaining a healthy digestive system is important for vegetarians.

Optimizing Vitamin K Absorption on a Plant-Based Diet

Since vitamin K is a fat-soluble vitamin, combining sources with a healthy fat is crucial for optimal absorption.

Cooking with Fat: Sautéing leafy greens in olive or soybean oil helps the body absorb more K1.
Adding Fat to Salads: Adding avocado, nuts, or an oil-based dressing to a kale or spinach salad significantly enhances absorption.
Snacking on Nuts: Cashews and pine nuts contain both vitamin K and healthy fats, making them an ideal snack.

Vitamin K1 vs. Vitamin K2: A Comparison for Vegetarians


Aspect	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinone)
Primary Sources	Abundant in dark leafy greens (spinach, kale), broccoli, and vegetable oils.	Found in fermented foods (especially natto), some dairy, and produced by gut bacteria.
Main Function	Primarily involved in the liver's production of blood clotting proteins.	Important for directing calcium to bones and away from arteries.
Vegetarian Intake	Generally very high, as plant sources are staples in a balanced vegetarian diet.	Can be obtained through fermented foods and bacterial conversion; supplementation is an option but often unnecessary.

Beyond Diet: Other Causes of Vitamin K Deficiency

It's important to remember that diet is not the only factor in vitamin K status. True deficiencies in adults are usually linked to underlying medical conditions or medications. These risk factors include:

Malabsorption Disorders: Conditions like celiac disease or Crohn's can impair the body's ability to absorb fats, and thus vitamin K.
Medications: Certain drugs, particularly blood thinners like warfarin and long-term antibiotics, can interfere with vitamin K metabolism or production by gut bacteria.
Liver Disease: Since vitamin K is stored in the liver, liver disorders can affect its reserves.

Conclusion: The Final Word on Vegetarians and Vitamin K

Concerns about whether vegetarians are deficient in vitamin K are largely unfounded, provided a varied and balanced diet is followed. While the K2 form is more common in animal products, vegetarians and vegans can obtain sufficient amounts through fermented plant foods like natto and from their gut bacteria. By focusing on regular consumption of leafy greens, cruciferous vegetables, and fermented foods, and by pairing them with healthy fats, vegetarians can feel confident in their vitamin K intake. True deficiency is rare in healthy adults and more often tied to medical conditions or medication use rather than diet alone.

For more detailed information on recommended daily intakes, consult resources like the NIH Office of Dietary Supplements.

Frequently Asked Questions

Vitamin K1 (phylloquinone) is found in plant foods, particularly green leafy vegetables, while vitamin K2 (menaquinone) is produced by gut bacteria and found in fermented foods and some animal products.

Yes, while K2 is less common in plant-based diets, vegetarians can get it from fermented foods like natto and sauerkraut. The body's gut bacteria also produce some K2 from K1.

Excellent plant-based sources of vitamin K1 include dark leafy greens such as kale, spinach, and collard greens, as well as broccoli, Brussels sprouts, and soybeans.

To increase absorption, vegetarians should combine vitamin K-rich foods with a source of healthy fat. For example, add avocado or a drizzle of olive oil to a spinach salad.

Signs of vitamin K deficiency include excessive bleeding from minor cuts, easy bruising, and blood in the urine or stool. In severe cases, it can affect bone health.

Most healthy vegetarians do not need supplements, as a balanced diet provides adequate vitamin K. Supplements should be discussed with a doctor, especially if you take blood thinners.

Yes, deficiency in adults is more often caused by underlying health issues like malabsorption disorders (e.g., Crohn's disease), liver disease, or taking certain medications like warfarin.