What Does Vitamin K1 Do for Your Body?

November 21, 2025 •

2 min read

According to the National Institutes of Health, vitamin K is a fat-soluble vitamin stored in the liver and other tissues. A key component for health, this nutrient, and specifically vitamin K1, plays several critical roles in maintaining bodily functions.

Quick Summary

Vitamin K1 is essential for blood clotting, helping to activate necessary proteins. It also supports bone and heart health, with leafy greens being a primary source.

Key Points

Blood Clotting: Vitamin K1 is crucial for producing clotting factors in the liver.
Bone Mineralization: It activates proteins that help bind calcium to bones.
Arterial Health: Evidence suggests vitamin K1 helps prevent the calcification of arteries.
Dietary Sources: Excellent sources include leafy greens such as kale and spinach.
K1 vs. K2: K1 is primarily derived from plants and mainly affects liver-dependent functions.
Medication Interaction: Those on blood-thinners like warfarin must maintain a consistent vitamin K intake.

The Primary Role of Vitamin K1: Blood Coagulation

Vitamin K1, or phylloquinone, is predominantly found in plants like dark leafy greens. Its main function is blood clotting, a process from which the "K" in its name, derived from the German word "Koagulation," originates. Vitamin K1 is necessary for producing clotting factors. It acts as a cofactor for an enzyme that modifies these proteins, allowing them to function and prevent excessive bleeding. Newborns receive a vitamin K injection to prevent a rare bleeding disorder.

Supporting Bone Health and Density

Vitamin K1 is also involved in bone health by activating osteocalcin, a protein that helps incorporate calcium into the bone matrix for mineralization. This process is crucial for bone strength and may reduce osteoporosis and fracture risk. Studies have linked higher vitamin K intake to better bone density. Research is ongoing regarding the specific roles of K1 and K2 in bone health.

Contribution to Cardiovascular Wellness

Studies suggest vitamin K1 may benefit heart health by helping to prevent arterial calcification. It activates Matrix Gla Protein (MGP), which may inhibit calcium deposition in soft tissues, including arteries. Calcium buildup in arteries is a heart disease risk factor. Higher vitamin K1 intake has been associated with a lower risk of heart disease hospital admission. Consistent vitamin K intake is vital for those taking blood thinners like warfarin.

How Vitamin K1 and K2 Differ

Vitamin K1 (phylloquinone) and K2 (menaquinones) are distinct forms with different sources and body distribution.


Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinone)
Primary Source	Plant-based foods.	Animal products and fermented foods.
Absorption	Less efficiently absorbed from plants.	Thought to be better absorbed.
Circulation Time	Stays in blood for hours.	Remains in blood for days.
Primary Function Site	Primarily used by the liver.	Redistributes to tissues like bone and arteries.

Important Sources of Vitamin K1

Dietary intake of vitamin K1 is important. As it is fat-soluble, consuming it with healthy fat can improve absorption.

Dark Leafy Greens: Rich sources include kale, spinach, and collard greens. A cup of cooked kale can exceed the daily requirement.
Cruciferous Vegetables: Broccoli and Brussels sprouts are good sources.
Certain Oils: Soybean and canola oils contain K1.
Other Vegetables: Green beans, cabbage, and parsley also contribute.

Conclusion: A Vital Nutrient for Foundational Health

Vitamin K1 is essential for blood clotting and supports bone and cardiovascular health. A diet rich in leafy greens typically provides sufficient K1 for most adults. Those on blood thinners should maintain consistent intake and consult a healthcare provider. Further research will clarify the roles of K1 and K2. For more information, consult the {Link: National Institutes of Health https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/}.

Frequently Asked Questions

Vitamin K1 (phylloquinone) is mainly found in leafy green plants and is essential for blood clotting. {Link: Getlabtest website https://www.getlabtest.com/news/post/vitamin-k1-benefits-sources-health}.

{Link: Getlabtest website https://www.getlabtest.com/news/post/vitamin-k1-benefits-sources-health}.

Severe vitamin K1 deficiency is rare in healthy adults. However, it can occur in newborns (who are routinely given a shot at birth) or in individuals with conditions that affect nutrient absorption, such as celiac disease or cystic fibrosis.

Symptoms of a vitamin K1 deficiency include excessive bleeding from cuts or wounds, easy bruising, nosebleeds, and blood in the urine or stool. In severe cases, internal bleeding can occur.

Yes, vitamin K1 can interfere with blood-thinning medications like warfarin (Coumadin). Patients on these medications must maintain a consistent daily intake of vitamin K and should always consult their doctor before changing their diet or starting supplements.

According to the NIH, the adequate daily intake for adult men is 120 mcg and for adult women is 90 mcg. Most people can meet this requirement through a healthy and varied diet.

It is extremely rare to get too much vitamin K1 from food alone, and there is no established upper limit for consumption. {Link: Getlabtest website https://www.getlabtest.com/news/post/vitamin-k1-benefits-sources-health}.