Fat-soluble vitamins

Vitamin K

Coagulation · bone

Blood clotting and bone matrix protein activation.

Daily target

120 mcg

FDA Daily Value

Upper limit

None

No UL established

Catalog matches

supplements in our catalog

What Vitamin K does

Vitamin K is required to gamma-carboxylate clotting factors II, VII, IX, X and bone-matrix proteins like osteocalcin. Two natural forms differ meaningfully: K1 (phylloquinone) from leafy greens primarily supports clotting; K2 (menaquinones, MK-4 through MK-9) from fermented foods and animal products has a longer half-life and is more active in vascular and bone tissue. There's no UL because no toxicity has been observed at high intakes — but warfarin users must keep K intake stable, since K reverses the anticoagulant effect.

Food sources of Vitamin K

Approximate Vitamin K content per serving. Whole-food intake counts toward your daily total alongside any supplemental dose.

Food	Serving	Vitamin K
Cooked kale	1 cup	1,060 mcg K1
Cooked spinach	1 cup	890 mcg K1
Cooked broccoli	1 cup	220 mcg K1
Natto (fermented soy)	1 oz	300 mcg K2 (MK-7)
Hard cheese	1 oz	10 mcg K2
Egg yolk	1 large	30 mcg K2

Signs of Vitamin K deficiency

●Easy bruising, prolonged bleeding from minor cuts
●Heavy menstrual bleeding, nosebleeds
●Elevated prothrombin time (PT/INR) on a coagulation panel
●Newborns: hemorrhagic disease of the newborn (why a K injection is given at birth)

Who needs more Vitamin K

Groups and situations where Vitamin K requirements rise or status commonly runs low:

●Long-term broad-spectrum antibiotic use — disrupts gut flora that synthesize K2
●Fat-malabsorption (cystic fibrosis, biliary atresia, IBD)
●Very low intake of leafy greens
●Bone-health-focused supplementation may benefit from added MK-7

How Vitamin K appears on labels

Supplement labels list Vitamin K under several names depending on the chemical form used. Any of these on an ingredients panel counts toward your Vitamin K intake:

vitamin k
vitamin k1
vitamin k2
phylloquinone
menaquinone
mk-4
mk-7

Best supplements for Vitamin K

Top-scoring supplements in our catalog that list Vitamin K on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.

Transparent Labs

Vitamin D3 K2

Thorne

Vitamin D + K2 Liquid

Thorne

Vitamin K2

Thorne

Basic Nutrients 2/Day

Deep dive

For mechanism of action, dosing protocols, evidence grade, and interaction warnings on Vitamin K, see the full encyclopedia entry:

Vitamin K encyclopedia entry →

Research on Vitamin K

Peer-reviewed studies in our research database that reference Vitamin K. Each entry links to a detailed methodology review.

Guides covering Vitamin K

Long-form articles in our guide library that go deeper on Vitamin K — comparisons, protocols, and reviews.

Review · 9 min read
Ashwagandha for Testosterone: What the Evidence Actually Shows

Frequently asked questions

What is the daily target for Vitamin K?

The fda daily value for Vitamin K is 120 mcg per day for adults. No Tolerable Upper Intake Level has been established.

What foods are highest in Vitamin K?

Cooked kale (1,060 mcg K1 per 1 cup); Cooked spinach (890 mcg K1 per 1 cup); Cooked broccoli (220 mcg K1 per 1 cup). See the food sources section below for the full list.

What is the best form of Vitamin K to supplement?

K2 as MK-7 has a much longer half-life (~3 days) than MK-4 (~1 hour) — once-daily MK-7 dosing is practical; MK-4 needs split doses to maintain levels. K1 is well-covered if you eat cooked greens regularly.

What are the signs of Vitamin K deficiency?

Easy bruising, prolonged bleeding from minor cuts; Heavy menstrual bleeding, nosebleeds; Elevated prothrombin time (PT/INR) on a coagulation panel.

Who is most at risk for low Vitamin K?

Long-term broad-spectrum antibiotic use — disrupts gut flora that synthesize K2; Fat-malabsorption (cystic fibrosis, biliary atresia, IBD); Very low intake of leafy greens.

Related fat-soluble vitamins

Track your full intake

Formulate's free web app aggregates Vitamin K (and ~40 other nutrients) across every supplement in your stack — flagging underdoses, overlaps, and upper-limit overshoots in one view.

Track your intake free →

Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Targets and upper limits are general adult reference values; individual needs vary by age, sex, pregnancy status, and clinical context.