Vitamin K
Also known as Phylloquinone (K1), Menaquinones (K2)
Vitamin K is a fat-soluble vitamin best known for its essential role in blood clotting. It also helps build and maintain healthy bones by activating proteins that bind calcium.
Why it matters
What it does in your body
- Blood clotting (coagulation)
- Bone metabolism and mineralization
- Activating vitamin K-dependent proteins
- Regulating calcium in blood vessels
By age, sex, and life stage
How much you need
All vitamin K values are Adequate Intake (AI), not RDA, because there was not enough evidence to set an RDA. Amounts are in mcg and refer mainly to phylloquinone (vitamin K1), the primary dietary form.
Recommended intake across life
in mcg/dayBars scale to the highest recommendation shown. Where men and women differ, both values are listed.
Full reference table
| Life stage | Male | Female |
|---|---|---|
| Infants 0-6 mo | 2.0 (AI) | 2.0 (AI) |
| Infants 7-12 mo | 2.5 (AI) | 2.5 (AI) |
| Children 1-3 | 30 (AI) | 30 (AI) |
| Children 4-8 | 55 (AI) | 55 (AI) |
| Children 9-13 | 60 (AI) | 60 (AI) |
| Teens 14-18 | 75 (AI) | 75 (AI) |
| Adults 19+ | 120 (AI) | 90 (AI) |
| Pregnancy | n/a | 90 (AI) |
| Lactation | n/a | 90 (AI) |
Values in mcg/day. AI marks an Adequate Intake, used when there is not enough evidence for a formal recommendation.
What moves the number
What changes your needs
Age
Needs rise steadily from infancy through the teen years and reach the adult level around age 19, then stay constant with no increase in older adults.
Sex
From age 19 on, men have a higher AI (120 mcg) than women (90 mcg), largely reflecting differences in average body size.
Body weight / size
Adequate Intakes are set per life stage and sex rather than scaled to individual body weight, though body size underlies the higher male value.
Pregnancy and lactation
The AI stays at 90 mcg during pregnancy and lactation, the same as for other adult women.
Running low
Signs you might not get enough
Most at risk: Rare in healthy adults. Newborns not given vitamin K at birth are at risk of hemorrhagic disease, as are people with malabsorption disorders such as cystic fibrosis, celiac disease, ulcerative colitis, and short bowel syndrome, and those after bariatric surgery.
Too much
Can you get too much?
Vitamin K has no known toxicity from food or supplements. However, it interacts with anticoagulant drugs like warfarin, so people on these medications should keep their vitamin K intake consistent rather than changing it sharply.
Where to get it
Best food sources
The bottom line
Leafy green vegetables and some vegetable oils easily supply enough vitamin K for most people, and toxicity is not a concern. People taking blood thinners such as warfarin should keep their vitamin K intake steady rather than sharply changing it.
Track vitamin k automatically
Vitamin K is one of the 92 nutrients Vora reads from a photo of your meal, so you can see where you stand without weighing or logging by hand.
Sources and method
The recommended intakes, upper limits, and food-source amounts on this page come from the primary references below. Numbers were checked against the current NIH Office of Dietary Supplements fact sheets and the Institute of Medicine (now the National Academies) Dietary Reference Intakes.
- NIH Office of Dietary Supplements, Vitamin K Fact Sheet for Health Professionals
- Institute of Medicine (NASEM), Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc
This page is for general education, not medical advice. Reference intakes are population averages for healthy people and do not replace guidance from your doctor or a registered dietitian, especially if you are pregnant, managing a health condition, or considering supplements.