Vitamin K (as Phytonadione)
Also known as: Vitamin K1, Phylloquinone, Phytonadione, Menatetrenone
Effective Dosage
90-120 mcg/day (Adequate Intake); therapeutic doses vary by condition
What the Science Says
Vitamin K1 (phytonadione) is the plant-derived form of Vitamin K, found naturally in leafy green vegetables. It plays a well-established role in activating proteins that control blood clotting, helping wounds heal properly. It also activates proteins involved in bone metabolism, which is why it is commonly included in bone-health supplements. No clinical papers were provided for this analysis, so specific dosing claims and timeframes are based on general nutritional science rather than reviewed trial data.
What It Doesn't Do
Won't replace prescription blood-thinning medications — in fact, it can interfere with them. Not a proven treatment for osteoporosis on its own. No solid evidence it prevents heart disease or arterial calcification in otherwise healthy people. Doesn't provide the same benefits as Vitamin K2 (MK-7), which is a different form with different tissue distribution.
Evidence-Based Benefits
No papers were provided for this analysis, so no evidence-based efficacy claims can be made from the supplied literature. Phytonadione is the synthetic form of Vitamin K1, but without the actual abstracts, no specific findings can be cited or verified.
Weak EvidenceEffective at: No data from provided studies
Source: auto-research
Absorption & Bioavailability
Moderate — Vitamin K1 is fat-soluble and requires dietary fat for absorption. Bioavailability is significantly improved when taken with a meal containing fat. Absorption is generally lower than Vitamin K2 forms.
Red Flags to Watch For
- Serious drug interaction: Vitamin K1 directly counteracts warfarin (Coumadin) and other anticoagulants — even small supplemental doses can destabilize INR levels and increase clotting risk
- Often confused with Vitamin K2 (MK-4 or MK-7) in marketing — these are different compounds with different functions; check the label carefully
- No clinical papers were provided for this analysis — specific efficacy claims cannot be verified from reviewed research
- Supplements containing 1000+ mcg far exceed the Adequate Intake of 90-120 mcg/day; high doses are not proven to offer additional benefit and may pose risks for people on blood thinners
Products Containing Vitamin K (as Phytonadione)
See how Vitamin K (as Phytonadione) is used in these analyzed products:
Research Sources
- General knowledge
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06