Vitamin K Supplement Amounts for Adults
For general adult supplementation, provide 90 μg/day for women and 120 μg/day for men, or use the simplified recommendation of 1 μg/kg body weight per day (approximately 70 μg/day for average adults). 1, 2
Standard Daily Recommendations
The adequate intake (AI) for vitamin K varies slightly between authoritative sources but converges on similar values:
- EFSA recommendation: 1 μg/kg body weight per day for all adults, which translates to approximately 70 μg/day for average body weights 2
- Institute of Medicine (IOM) recommendation: 120 μg/day for adult males and 90 μg/day for adult females 1, 3
- Average dietary intake: Young adults typically consume approximately 80 μg/day, while older adults consume approximately 150 μg/day from food sources 4
Context-Specific Supplementation Amounts
Bariatric Surgery Patients
After biliopancreatic diversion (BPD): Provide 300 μg vitamin K daily as part of routine supplementation due to malabsorption risk 1
Parenteral Nutrition
Standard PN supplementation: Provide at least 150 μg phylloquinone per day in addition to amounts naturally present in lipid emulsions 1, 5
Treatment of Vitamin K Deficiency
When treating documented deficiency:
- Initial treatment: 10 mg intramuscularly or subcutaneously 1
- Maintenance after deficiency correction: 1-2 mg/week parenterally or orally 1
- Oral treatment for deficiency: 1-2 mg daily using menadiol sodium phosphate or phytomenadione 1
Critical Contraindication
Patients on anticoagulants (warfarin): Should NOT receive vitamin K supplements, as this interferes with anticoagulation control 1. The KDOQI guidelines explicitly state it is reasonable that patients receiving anticoagulant medicines known to inhibit vitamin K activity do not receive vitamin K supplements 1.
Special Populations
Enteral Nutrition
Standard enteral formulas typically provide 3.5-20 μg/100 kcal, generally meeting recommended daily doses with 1500 kcal intake 1
Patients with Fat Malabsorption
Those with conditions causing fat malabsorption (celiac disease, cystic fibrosis, short bowel syndrome, cholestatic liver disease) are at high risk for deficiency and may require higher supplementation doses 1
Important Clinical Considerations
Absorption characteristics: Vitamin K absorption from food matrices is poor, and the vitamin is primarily obtained from leafy green vegetables and certain vegetable oils (soybean, cottonseed, canola, olive) 4, 6
Safety profile: Natural forms of vitamin K (K1 and K2) have no proven toxicity at typical supplementation doses 1, 5. The upper tolerable limit is not established due to lack of toxicity concerns with natural forms 1.
Monitoring: Standard coagulation tests are nonspecific and insensitive for vitamin K status; better assessments include plasma vitamin K levels (<0.15 μg/L indicates deficiency) or undercarboxylated protein measurements 1, 5