Vitamin K is often overshadowed by more well-known vitamins like C, D, and E, yet it plays critical roles in bone strength and blood clotting. Without adequate vitamin K, the body cannot properly regulate calcium or clot blood efficiently. Although deficiency is uncommon, low levels may affect long-term wellness. Let’s explore what vitamin K does, its food sources, and why it deserves more attention in everyday nutrition.

What Is Vitamin K?

Vitamin K is a fat-soluble vitamin that comes in two main forms:

  • Vitamin K1 (phylloquinone): Found primarily in green leafy vegetables.

  • Vitamin K2 (menaquinones): Found in animal-based foods and fermented products, also produced in small amounts by gut bacteria.

Both forms are important for health, though K1 is more abundant in the diet, and K2 may have unique roles in bone and heart health.

Functions of Vitamin K

Vitamin K contributes to several vital processes:

  1. Blood Clotting

    • Essential for the synthesis of clotting factors in the liver.

    • Helps wounds heal properly by enabling blood coagulation.

  2. Bone Health

    • Assists proteins that regulate calcium in bones and tissues.

    • Works alongside vitamin D to support bone mineralization.

  3. Cardiovascular Balance

    • Helps prevent calcium deposits in arteries.

    • Supports vascular elasticity and overall cardiovascular wellness.

Vitamin K and Blood Clotting

One of vitamin K’s most essential roles is in producing proteins that allow blood to clot. Without it, even minor injuries could lead to excessive bleeding. This is why newborns, who are naturally low in vitamin K, are often given a vitamin K injection shortly after birth.

Vitamin K and Bone Health

Vitamin K is involved in activating osteocalcin, a protein that helps bind calcium to the bone matrix. Adequate intake is associated with better bone density and lower risk of fractures. Together with vitamin D and calcium, vitamin K plays a synergistic role in maintaining skeletal health.

Food Sources of Vitamin K

Vitamin K is abundant in many everyday foods.

  • Vitamin K1 (phylloquinone):

    • Kale

    • Spinach

    • Broccoli

    • Brussels sprouts

    • Lettuce

  • Vitamin K2 (menaquinones):

    • Cheese

    • Egg yolks

    • Liver

    • Fermented foods like natto (a traditional Japanese soybean dish)

A balanced diet with leafy greens and some fermented foods helps ensure adequate intake.

Daily Requirements of Vitamin K

The recommended intake varies by age and sex:

  • Adult men: ~120 micrograms (mcg) per day

  • Adult women: ~90 mcg per day

Since it is fat-soluble, vitamin K is best absorbed when consumed with dietary fats such as olive oil or avocado.

Vitamin K Deficiency

Deficiency is rare but can occur in:

  • People with digestive disorders affecting fat absorption (such as celiac or Crohn’s disease).

  • Individuals on long-term antibiotic therapy (which may reduce gut bacteria that produce K2).

  • Newborn babies (due to low stores at birth).

Symptoms may include:

  • Easy bruising

  • Excessive bleeding

  • Weak bones over time

Excess Vitamin K

Vitamin K from food is generally safe. Unlike some other fat-soluble vitamins, toxicity is rare because the body can regulate excess intake. However, those taking blood-thinning medications should monitor vitamin K intake carefully, as it can affect how these medicines work.

Vitamin K and Long-Term Wellness

Beyond clotting and bone support, vitamin K may play additional roles:

  • Heart health: By reducing calcium buildup in arteries.

  • Healthy aging: Through its interaction with bone and vascular systems.

While more research is ongoing, it is clear that vitamin K contributes to foundational aspects of health that are often overlooked.

Conclusion

Vitamin K may not get as much attention as other vitamins, but it is essential for life. From helping blood clot properly to strengthening bones and supporting cardiovascular health, vitamin K works quietly in the background to keep the body functioning.

Eating leafy greens like spinach and kale, along with some fermented foods or animal products, ensures you get enough of this vital nutrient. Pairing it with healthy fats improves absorption and maximizes its benefits.