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Research Preview — Unreviewed AI Research

Warfarin

vitamin K antagonist anticoagulant

Also sold as Coumadin, Jantoven.

Based on official regulatory labeling and NIH federal guidance concerning warfarin and nutrient-related effects, this research packet documents warfarin's classic, well-established relationship with dietary and supplemental vitamin K, a related caution about high-dose vitamin E, and a general label caution naming several botanical supplements. A widely discussed cranberry-juice question could not be verified this session and is withheld pending further research.

Researched 9/3/2026

Evidence summary

Qualifying findings
0
Interactions and timing
1
Searched, nothing found
0
Verified cited sources
1 of 1
Human review
Not yet reviewed
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Overview

Research Preview — Unreviewed AI Research

AI-assisted Research Preview - not yet human-reviewed and not part of Published Knowledge.

This is automated research that has not yet been reviewed by a person. It is not MyDeficiencies published knowledge, it is not medical advice, and it may be incomplete or wrong. It has been added to our editorial review queue.

vitamin K antagonist anticoagulant. Based on official regulatory labeling and NIH federal guidance concerning warfarin and nutrient-related effects, this research packet documents warfarin's classic, well-established relationship with dietary and supplemental vitamin K, a related caution about high-dose vitamin E, and a general label caution naming several botanical supplements. A widely discussed cranberry-juice question could not be verified this session and is withheld pending further research.

Researched 9/3/2026 · Adversarial review ran: 3 confirmed, 1 scope corrections, 1 rejected.

1 of 1 cited sources were confirmed to exist as described. That check confirms the source is real, not that it supports the claim.

Qualifying findings
0
Interactions and timing
1
Searched, nothing found
0
Verified cited sources
1 of 1
Human review
Not yet reviewed

Interactions and timing

How this medication and a nutrient affect each other's absorption, handling or timing. This is not depletion.

Vitamin K

exact entity

Interaction and timing

Both warfarin's official prescribing information and the NIH Office of Dietary Supplements report that vitamin K — from food or supplements — can reduce warfarin's blood-thinning effect, and that keeping vitamin K intake consistent from day to day is the standard guidance, rather than avoiding vitamin K altogether.

1 cited source and detail

How this medication and this nutrient affect each other's absorption, handling or timing. This is not the same as depletion.

Relationship:
external factor (dietary/supplemental vitamin K) -> medication effect (Direction B)
Outcome measured:
medication nutrient interaction
Study population:
human studies
Agreement:
1 supporting, 0 contradicting

What was measured: anticoagulant effect / INR (international normalized ratio)

Proposed mechanism: Warfarin works by blocking the body's use of vitamin K to build certain clotting factors. When vitamin K intake rises, that opposition is partly offset, which can shift anticoagulation control. A mechanism explains how an effect could occur. It is not itself a measured clinical outcome.

1 of 1 cited sources were checked and found to support this specific claim. A source existing is not the same as a source supporting the claim.

Why it is here: Concordant official-label and NIH-authoritative-fact-sheet statements; a textbook-level, well-established mechanism and clinical guidance.

Evidence limitations

What this cannot tell you

  • The guidance from both official sources is about maintaining steady intake, not eliminating vitamin K-containing foods. Sudden large increases or decreases in either direction are described as the actual risk, and any dietary change should be discussed with the clinician managing INR monitoring.
  • The systematic review located in the original pass (PMC4998867) remains unretrieved. One of the 5 controlled cranberry studies (PMID 20642557) was confirmed only bibliographically; its abstract was not obtained.

AI-assisted Research Preview - not yet human-reviewed and not part of Published Knowledge. Educational information only. Not medical advice, diagnosis or treatment. Talk to your prescriber or pharmacist before changing any medication or supplement.

Sources

Only sources attached to information shown above are listed here.

Questions for your clinician

These are conversation prompts, not findings about you.

  • Could Warfarin affect any nutrients over time in my situation?
  • Are there symptoms or risk factors that would make further evaluation appropriate?
  • Could diet, other medications, or health conditions affect this relationship?
  • Would laboratory testing be clinically appropriate for me?
  • Are there medication or supplement interactions I should understand?

Review status

Human review

Published Knowledge is human-reviewed. Research Previews are clearly labeled and have not yet completed human review.

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Derived from acceptance run artifacts/candidate-workbooks/MyDeficiencies_Claude_Cardiovascular_Candidate_Intelligence_Batch-001_FINAL-CORRECTED_2026-09-02.xlsx (373fbbf11d03).