Vitamin K
Needed for blood clotting and bone proteins.
The formula matches the form shown in the 3D model. Other forms of this vitamin can have different formulas.Loading molecular structure…
Phylloquinone (K1) · Drag to rotate
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One representative form. Hydrogens omitted; bonds simplified.
PubChem · CID 5284607Where you can find it
- Kale
- Spinach
- Broccoli
- Soybeans
- Vegetable oils
What it does in the body
Vitamin K helps make proteins involved in blood clotting and bone metabolism.
Recommended amounts & upper limit
US reference values for healthy adults aged 19–50, excluding pregnancy and breastfeeding. These are daily dietary intakes, not blood-test ranges or prescribed supplement doses. Other ages and life stages have different needs; see the original source.
- Men · AI
- 120 mcg/day
- Women · AI
- 90 mcg/day
- Upper limit · UL
- No established ULNo UL for naturally occurring K1 and K2; medicine interactions still matter.
How to read these levels
RDA means Recommended Dietary Allowance; AI means Adequate Intake, used when an RDA cannot be set. The upper limit (UL) is not a target or an exact toxicity threshold. Going below the RDA on one day does not diagnose deficiency. No established UL does not mean unlimited amounts are safe.
mg = milligrams; mcg = micrograms. 1 mg = 1,000 mcg. IU is vitamin-specific and cannot be converted with one rule for all vitamins.
What happens when the balance changes?
These are possible effects, not a diagnosis or a prediction from one low or high result.
Too little
Severe deficiency impairs clotting and can cause bruising or bleeding.
Body areas affected
Blood clotting throughout the body.
Too much
Direct toxicity is not established for K1 or K2. Sudden intake changes can alter warfarin's effect, raising clotting or bleeding risk.
Body areas affected
Clotting control during warfarin treatment.
What about blood-test levels?
Blood-test levels and daily intake use different units and cannot be compared directly. Test methods, reference ranges and clinical context vary. Symptoms alone cannot establish a vitamin deficiency or toxicity; a clinician can decide which tests and treatment are appropriate.
The body connection
Clotting proteins help prevent excessive bleeding after injury.
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