Nezam El-Tayebat Fact CheckA scientific assessment of the “نظام الطيبات” nutrition system
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Potentially true True only under certain conditions Certainty of evidence: moderate provisional C-VEG-12

Vitamin K in leafy greens destabilises warfarin therapy (archive citing a Medicine (Baltimore) review).

Safety note: Patients on vitamin K antagonists (warfarin, phenprocoumon, acenocoumarol) should not suddenly start or stop large amounts of leafy greens without informing their doctor or anticoagulation clinic, because both increases and decreases in vitamin K intake can change INR; abruptly removing greens (as an elimination diet would) can raise INR and bleeding risk. A consistent intake is recommended, not avoidance. Never stop or change anticoagulant medication on the basis of a diet.
In short: Partly true: large, sudden changes in the amount of vitamin K-rich greens can shift the effect of warfarin-type drugs, but eating greens consistently does not destabilise therapy and avoidance is not recommended; stopping greens abruptly can itself raise INR and bleeding risk.
Conclusion: Partly true: big sudden changes in greens can shift warfarin's effect, but consistent intake is safe and avoidance is not advised; the archive reverses its own source's conclusion.
  1. Original statement
  2. Scientific assessment
  3. Scientific evidence in detail
  4. In plain language
  5. Studies on this claim
  6. Regional context
  7. What applies in my country?
  8. References

Original statement

No Arabic original wording available.

Translation

Vitamin K in leafy greens destabilises warfarin therapy (archive citing a Medicine (Baltimore) review).

Origin

Source status
Archive editors
Attribution
Archive editors
Origin
https://eltayebat.com/rule/leafy-greens-cucurbits/
Attribution uncertainty
Archive editorial text and study selection written by the archive operators, not necessarily by Elawady.
Claimed mechanism

Vitamin K antagonises vitamin K antagonists.

Claimed health effect

Unstable INR.

Population concerned

Patients on vitamin K antagonists

Geographic restriction by Elawady

none found

Scientific assessment

Potentially true – Some evidence points in favour of the statement, but it is not sufficient for a clear judgement.

Certainty of evidence: moderate – Further research may still affect the assessment.

1. What was claimed?

Greens destabilise warfarin therapy.

2. What is demonstrably correct?

Vitamin K reverses the effect of warfarin and phenprocoumon. Large, sudden changes in the amount of vitamin K-rich greens eaten can shift INR: in a randomized crossover trial, a vitamin K-depleted diet raised INR from 2.6 to 3.3 and an enriched diet lowered it from 3.1 to 2.8 (Franco 2004); a weekly change of about 714 ug of dietary vitamin K changed INR by about one unit (Couris 2006). Health services (NHS, MedlinePlus) state that green leafy vegetables can affect warfarin.

3. What is wrong or exaggerated?

The implied conclusion that greens should be avoided is wrong. A consistent intake of greens does not destabilise therapy; low and erratic vitamin K intake is associated with more unstable control (Dentali 2016), and a steady daily vitamin K supplement improved stability in a double-blind RCT (Sconce 2007). Abruptly stopping greens is itself a change that can raise INR and bleeding risk. The archive's cited review (Violi 2016) concluded that evidence does not support advising dietary restriction and recommended stable habits; the archive reverses this conclusion. Newer anticoagulants (DOACs) are not affected by vitamin K.

4. What remains unclear?

How much realistic day-to-day variation in greens changes INR; effects on bleeding and clotting events are not measured in the dietary studies.

5. Which studies support it?

Franco 2004 (I-VEG-101); Couris 2006 (I-VEG-102); Schurgers 2004 (I-VEG-103, effect from about 150 ug/day); NHS and MedlinePlus guidance.

6. Which studies contradict it?

Against avoidance: Sconce 2007 (I-VEG-104); Dentali 2016 (I-VEG-105); Violi 2016 (A-VEG-17); Schurgers 2004 (food-borne vitamin K effects short-lived).

7. What applies to Germany and Europe?

Phenprocoumon is the main vitamin K antagonist in Germany; similar principle applies.

8. What is known about Egypt?

Not specific.

9. What practical conclusion is appropriate?

People taking warfarin or phenprocoumon can eat leafy greens but should keep the amount roughly consistent from week to week and should not suddenly start or stop large amounts without telling their anticoagulation clinic, because INR may need checking and the dose adjusting.

Assessment details

Rationale for certainty of evidence

Vitamin K is the pharmacological antidote of vitamin K antagonists. A randomized crossover feeding trial (Franco 2004, I-VEG-101: INR 2.6 to 3.3 on a vitamin K-depleted diet, 3.1 to 2.8 on an enriched diet), a prospective food-record study (Couris 2006, I-VEG-102: about 714 ug/week change per INR unit) and a dose-response study (Schurgers 2004, I-VEG-103: effect from about 150 ug/day) show that substantial changes in vitamin K intake shift INR. Health-service guidance (NHS 2026; MedlinePlus) agrees and advises consistent intake. The same evidence shows that a stable intake is compatible with stable therapy and that low intake is linked to instability (Sconce 2007 RCT, I-VEG-104; Dentali 2016, I-VEG-105; Violi 2016, A-VEG-17). Studies are small, hence moderate rather than high certainty.

Source quality

Archive misrepresents the conclusion of its own source.

Regional transferability

Applies to patients on warfarin/phenprocoumon in Germany and Egypt.

Individual exceptions

Large sudden changes in vitamin K intake can affect INR; stable intake is advised.

Regional scope of the claim
not specified
Last reviewed
26 October 2026 provisional

Scientific evidence in detail

True only under certain conditions – The claim holds only for certain doses, groups of people, preparations or circumstances.

Research question: In patients taking vitamin K antagonists (warfarin, phenprocoumon, acenocoumarol), do intake and changes in intake of vitamin K-rich leafy greens destabilise anticoagulation (INR), and does avoidance or consistency improve stability?

Research question in detail (PECO)
Population
Adults on vitamin K antagonists
Intervention or exposure
Dietary vitamin K (mainly green leafy vegetables): level and week-to-week change
Comparison
Stable or lower vitamin K intake
Geographic scope
universal pharmacology
Outcomes
  • INR level and variability
  • time in therapeutic range
  • bleeding and thrombosis (rarely reported)

Study results as reported by the authors. Our assessment follows below.

What speaks for the claim?

  • Changing vitamin K intake shifts warfarin effect

    Franco V et al.. Am J Med 2004 · PMID 15121490 · DOI 10.1016/j.amjmed.2003.12.036 Randomised controlled trialabstract checkednewly added

    Randomized crossover feeding trial plus observational cohort in anticoagulated patients.

    Actual result
    Vitamin K-depleted diet: INR 2.6 -> 3.3 (P = 0.005); vitamin K-enriched diet: INR 3.1 -> 2.8 (P = 0.04); intake independently associated with over- and under-coagulation.
    Methodological quality
    moderate (randomized, objective outcome, but n = 12 and extreme 4-day diets)
    Relevance
    direct: tests dietary vitamin K changes in patients
    Limitations
    Very small; short; extreme changes.

    Original publication

  • Week-to-week vitamin K swings move INR

    Couris R et al.. Int J Vitam Nutr Res 2006 · PMID 16941417 · DOI 10.1024/0300-9831.76.2.65 Cohort studyabstract checkednewly added

    Prospective 5-week food-record study in new warfarin users.

    Actual result
    Weekly change of 714 ug vitamin K changed INR by 1 unit; r = -0.60 between intake change and INR variability.
    Methodological quality
    moderate-low (prospective but small, 28% drop-out)
    Relevance
    direct
    Limitations
    Early titration phase; small.

    Original publication

  • How much vitamin K changes warfarin effect

    Schurgers LJ et al.. Blood 2004 · PMID 15231565 · DOI 10.1182/blood-2004-04-1525 Otherabstract checkednewly added

    Dose-response study in anticoagulated volunteers.

    Actual result
    Significant INR lowering from 150 ug/day vitamin K1; clinically relevant in 25% at that dose; food vitamin K effects short-lived.
    Methodological quality
    moderate (controlled dose-response)
    Relevance
    indirect: healthy volunteers, supplements
    Limitations
    Volunteers; supplements; also limits the claim.

    Original publication

What speaks against the claim?

  • Steady vitamin K can stabilise warfarin

    Sconce E et al.. Blood 2007 · PMID 17110451 · DOI 10.1182/blood-2006-09-049262 Randomised controlled trialabstract checkednewly added

    Double-blind RCT of 150 ug/day vitamin K vs placebo in unstable warfarin patients.

    Actual result
    Time in range +28% vs +15% (P < .01); stable control 19/35 vs 7/33 (recalculated RR 2.56, 1.24-5.28).
    Methodological quality
    moderate-high (double-blind RCT, small)
    Relevance
    indirect: supplement; shows steady vitamin K improves stability
    Limitations
    n = 70; selected patients.

    Original publication

  • Low vitamin K intake linked to unstable warfarin control

    Dentali F et al.. Semin Thromb Hemost 2016 · PMID 27232386 · DOI 10.1055/s-0036-1581105 Systematic reviewabstract checkednewly added

    Systematic review of 15 studies (1,838 patients).

    Actual result
    Lower daily vitamin K intake associated with unstable anticoagulation; supplementation may improve time in range in unstable patients.
    Methodological quality
    low-moderate (narrative SR)
    Relevance
    direct
    Limitations
    Overlaps with A-VEG-17.

    Original publication

  • Vitamin K foods and warfarin

    Violi F et al.. Medicine (Baltimore) 2016 · PMID 26962786 · DOI 10.1097/MD.0000000000002895 Systematic reviewfull text, structured risk-of-bias assessment

    Archive-cited systematic review (Violi 2016).

    Actual result
    Conflicting evidence; effects only above ~150 ug/day; authors conclude evidence does not support advising dietary modification and recommend stable habits.
    Methodological quality
    low (AMSTAR 2 high risk; small heterogeneous studies)
    Relevance
    direct
    Limitations
    Shares primary studies with I-VEG-105 and includes I-VEG-101.

    Original publication

What does the overall evidence say?

Editorial assessment based on the studies above – not itself a study result.

Which position is better supported?

Large, sudden changes in vitamin K intake (in either direction) shift INR; a consistent intake of leafy greens is compatible with stable therapy, and low or erratic intake is associated with instability. Avoiding greens is not recommended; consistency and informing the anticoagulation clinic are.

Why some studies weigh more

The randomized crossover and dose-response studies are direct but small; the double-blind RCT (Sconce) and the systematic reviews address consistency. Regulatory/health-service statements (NHS, MedlinePlus) agree that greens can affect warfarin and advise consistent intake rather than avoidance. Overlapping reviews (Violi, Dentali) are counted once.

Is a causal relationship established? Yes, established Vitamin K is the pharmacological antidote of VKAs; a dose-dependent effect of vitamin K intake on INR is mechanistically established and shown in controlled studies.

Remaining uncertainty

Size of INR effects from realistic day-to-day variation in greens; effect on clinical events (bleeding, thrombosis) is not measured.

Justified conclusion

Partly true: vitamin K from leafy greens can change warfarin effect when intake changes substantially. It does not follow that greens must be avoided; abruptly stopping greens is itself a change that can raise INR and bleeding risk. Not relevant to DOACs.

Why do studies seem to disagree?

Franco 2004 and Couris 2006 show INR shifts with dietary change, while Schurgers 2004 and Violi 2016 find food-borne vitamin K less potent and evidence for dietary advice weak. They answer different questions: the former test large changes; the latter address whether a stable or moderately varying intake needs restriction. Both are compatible with "keep intake consistent".

Does this depend on the country?
General biological effects
Universal pharmacology of vitamin K antagonists.
Eating habits
Relevant where greens such as molokhia, jarjir (rocket) and parsley are eaten in variable amounts.
Origin of the food
Vitamin K content varies by vegetable and preparation, not by country.
Contaminants
not applicable
National production conditions
not applicable
Legal rules
Drug labels and health services (NHS, NLM) advise consistent intake.
Actual monitoring data
not applicable

A regional difference that changes the conclusion is not supported by robust data.

Statistical re-check
  • Relative risk, absolute difference and NNT for achieving stable control (from reported counts 19/35 vs 7/33) – RR 2.56 (95% CI 1.24-5.28); ARR 33.1%; NNT 3 (not reported by authors). recalculated
  • Convert weekly vitamin K change per INR unit into daily amount – 714 ug/week = ~102 ug/day sustained change per INR unit. recalculated
  • Relative INR change in crossover arms – Depleted +27%; enriched -10% (direction: removal raises INR). recalculated
Certainty of the overall evidence (GRADE, simplified)
Main outcome
INR change after substantial change in dietary vitamin K
Starting level
high (randomised trials)
Reasons for downgrading
  • imprecision (very small trials)
  • indirectness (supplements, healthy volunteers in part)
Reasons for upgrading
  • dose-response gradient (Schurgers 2004; Couris 2006)
Result
moderate

Simplified assessment by a single reviewer, following the GRADE approach; not a formal GRADE panel. GRADE rates the body of evidence for one outcome, not individual studies.

Clinical guidelines and official statements checked
  • NHS (England): Warfarin: medicine used to prevent and treat blood clots (2026) · Original publication
    Talk to your doctor before making big changes to your diet; foods high in vitamin K such as broccoli, spinach and other green leafy vegetables can affect how warfarin works; you can still eat these foods, but talk to your warfarin clinic for advice (page reviewed 24 Feb 2026).
  • U.S. National Library of Medicine (MedlinePlus): Warfarin: MedlinePlus Drug Information (2026) · Original publication
    Eat a healthy diet; eat consistent amounts of vitamin K-containing food week to week; do not eat large amounts of leafy green vegetables or certain vitamin K-rich oils; talk to your doctor before making any changes to your diet.
  • NIH Office of Dietary Supplements: Vitamin K - Health Professional Fact Sheet · Original publication could not be retrieved; content not used
Search strategy

Documented literature searches for this review (search strings in the original database syntax).

DatabaseDateSearchLooking forHitsIncluded
Europe PMC26 October 2026(warfarin OR "vitamin K antagonist") AND ("dietary vitamin K" OR "vitamin K intake" OR "green leafy") AND (INR OR "anticoagulation stability" OR "time in therapeutic range")supporting evidence554
Europe PMC26 October 2026(warfarin OR acenocoumarol OR phenprocoumon) AND ("vitamin K" diet) AND (randomized OR "randomised" OR trial OR "meta-analysis")both directions2221
PubMed26 October 2026(warfarin OR "vitamin K antagonist*") AND ("dietary vitamin K" OR "vitamin K intake") AND (INR OR anticoagulation)supporting evidence120
Europe PMC26 October 2026TITLE:"vitamin K" AND TITLE:(warfarin OR anticoagula* OR acenocoumarol OR INR) AND (diet* OR intake OR vegetable*)both directions357
Europe PMC26 October 2026JOURNAL:"Cochrane Database Syst Rev" AND "vitamin K" AND warfarinboth directions191
PubMed26 October 2026"vitamin K" AND (warfarin OR "vitamin K antagonist*") AND ("anticoagulation control" OR stability) AND (systematic review[pt] OR meta-analysis[pt] OR randomized controlled trial[pt])both directions45
NHS website (guidance)26 October 2026https://www.nhs.uk/medicines/warfarin/ (food section)guidelines1
MedlinePlus (NLM)26 October 2026https://medlineplus.gov/druginfo/meds/a682277.html (dietary instructions)guidelines1
NIH ODS26 October 2026https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/ (HTTP 403, not used)guidelines0

Open questions

Whether structured dietary counselling (consistency) improves clinical outcomes; relevance for Egyptian dishes with very high vitamin K (molokhia).

How deeply was this checked?

6 linked studies: 1 checked in full text (1 of them with a structured risk-of-bias assessment), 5 on the basis of the abstract, 0 bibliographically only. No formal assessment with two independent reviewers and no independent human expert review has taken place yet.

Last scientific review: 26 October 2026

History of the verdict
  1. 25 October 2026 · Phase 1 · Initial assessment: Mostly false (low)
  2. 26 October 2026 · Phase 4 (systematic evidence review) · Verdict changed: Mostly false (low) → Potentially true (moderate)
    The previous rating relied mainly on the archive reversing the conclusion of Violi 2016. Primary controlled studies (Franco 2004 crossover; Couris 2006; Schurgers 2004 dose-response) and current health-service guidance (NHS 2026; MedlinePlus) confirm that substantial changes in leafy-green intake alter warfarin effect. The literal claim is therefore partly correct; what is wrong is the implied conclusion that greens should be avoided. The archive's misuse of Violi 2016 remains documented.
    New sources: I-VEG-101 I-VEG-102 I-VEG-103 I-VEG-104 I-VEG-105

In plain language

Warfarin and similar blood thinners work against vitamin K, which is found in leafy greens. If someone suddenly eats much more or much less greens, the blood-thinning effect can change, so the archive is partly right. But the answer is not to avoid greens: eating a similar amount regularly is compatible with stable treatment, and stopping greens suddenly can make the blood too thin. Patients should talk to their doctor or anticoagulation clinic before making big diet changes.

Studies on this claim

Studies supporting the claim (2)

  • Changing vitamin K intake shifts warfarin effect

    Franco V et al.. Am J Med 2004 · PMID 15121490 · DOI 10.1016/j.amjmed.2003.12.036
    Randomised controlled trialindependent cross-checkabstract checked★ key study

    In 12 patients, a diet low in vitamin K raised INR from 2.6 to 3.3 within a week, and a vitamin K-rich diet lowered it from 3.1 to 2.8.

    Large dietary vitamin K changes shift INR in both directions; abrupt removal raised INR.

    Does the study support the specific claim? Partly · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

    Original publication · Scientific details

    Study explained simply
    What did the researchers want to find out?

    To test whether dietary vitamin K changes anticoagulation.

    How was the study done?

    Observational follow-up plus a randomized crossover feeding trial.

    How many people, animals or samples were studied?

    39 clinic patients; 12 in the trial.

    What was actually found?

    Vitamin K intake was linked to both over- and under-anticoagulation; both diet changes moved INR.

    How large was the observed effect?

    INR +0.7 (depleted), -0.3 (enriched).

    What do the results mean in everyday life?

    Large sudden changes in greens intake can change how strongly warfarin works.

    What are the study's limitations?

    Tiny sample, 4-day diets, extreme changes.

    What does it say about Elawady's specific claim?

    Supports that greens can affect warfarin, but the problem is CHANGE in intake; stopping greens is also a change.

    Do the results apply to Germany and Europe?

    Applies to all vitamin K antagonists.

    What can explicitly not be concluded from this study?

    Cannot show that a stable intake of greens is harmful.

    Scientific details →

  • Week-to-week vitamin K swings move INR

    Couris R et al.. Int J Vitam Nutr Res 2006 · PMID 16941417 · DOI 10.1024/0300-9831.76.2.65
    Cohort studyindependent cross-checkabstract checked★ key study

    A weekly change of about 714 micrograms of vitamin K changed INR by about one unit in 43 new warfarin users.

    Quantifies INR change per change in vitamin K intake.

    Does the study support the specific claim? Partly · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

    Original publication · Scientific details

    Study explained simply
    What did the researchers want to find out?

    Quantify the effect of vitamin K variability on INR.

    How was the study done?

    Daily food records and weekly INR for 5 weeks.

    How many people, animals or samples were studied?

    43 completers.

    What was actually found?

    Bigger swings in vitamin K went with bigger swings in INR.

    How large was the observed effect?

    714 ug/week per 1 INR unit; r = -0.60.

    What do the results mean in everyday life?

    Eating very different amounts of greens from week to week can make INR unstable.

    What are the study's limitations?

    Small, short, early-treatment phase.

    What does it say about Elawady's specific claim?

    Supports "changes in greens intake affect warfarin", not "greens must be avoided".

    Do the results apply to Germany and Europe?

    Applies to all VKA users.

    What can explicitly not be concluded from this study?

    Cannot show that consistent greens intake is harmful.

    Scientific details →

Studies contradicting or limiting the claim (3)

  • Vitamin K foods and warfarin

    Violi F et al.. Medicine (Baltimore) 2016 · PMID 26962786 · DOI 10.1097/MD.0000000000002895
    Systematic reviewcited by the Tayebat archivefull text, structured risk-of-bias assessment★ key study

    Review found no good evidence that patients on warfarin should restrict leafy greens; stable intake matters.

    Does the study support the specific claim? No · Methodological quality: low · Certainty of evidence: see overall assessment of the claim

    Original publication · Scientific details

    Study explained simply
    What did the researchers want to find out?

    Assess diet-warfarin interaction

    How was the study done?

    Systematic review

    How many people, animals or samples were studied?

    11 studies

    What was actually found?

    Conflicting; no basis for restriction

    How large was the observed effect?

    Effect possibly >150 µg/day

    What do the results mean in everyday life?

    Keep intake stable.

    What are the study's limitations?

    Few studies

    What does it say about Elawady's specific claim?

    Contradicts archive

    Do the results apply to Germany and Europe?

    High

    What can explicitly not be concluded from this study?

    Cannot show greens must be avoided.

    Scientific details →

  • Steady vitamin K can stabilise warfarin

    Sconce E et al.. Blood 2007 · PMID 17110451 · DOI 10.1182/blood-2006-09-049262
    Randomised controlled trialindependent cross-checkabstract checked★ key study

    A daily 150 microgram vitamin K supplement more than doubled the share of unstable patients who reached stable control (19 of 35 vs 7 of 33).

    Steady vitamin K intake improved INR stability; contradicts "greens destabilise" as a general rule.

    Does the study support the specific claim? No · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

    Original publication · Scientific details

    Study explained simply
    What did the researchers want to find out?

    Test whether low-dose vitamin K stabilises warfarin control.

    How was the study done?

    Double-blind RCT, 6 months.

    How many people, animals or samples were studied?

    70 patients with unstable INR.

    What was actually found?

    Vitamin K improved stability and time in range.

    How large was the observed effect?

    Time in range +28% vs +15%.

    What do the results mean in everyday life?

    A constant intake of vitamin K is not the enemy of warfarin; big swings are.

    What are the study's limitations?

    Small, supplement not food.

    What does it say about Elawady's specific claim?

    Contradicts the idea that vitamin K-containing greens in themselves destabilise therapy.

    Do the results apply to Germany and Europe?

    Universal.

    What can explicitly not be concluded from this study?

    Cannot prove that eating more greens has the same effect.

    Scientific details →

  • Low vitamin K intake linked to unstable warfarin control

    Dentali F et al.. Semin Thromb Hemost 2016 · PMID 27232386 · DOI 10.1055/s-0036-1581105
    Systematic reviewindependent cross-checkabstract checked★ key study

    A review of 15 studies (1,838 patients) found unstable control more often in people with LOW vitamin K intake.

    Low vitamin K intake associated with unstable control.

    Does the study support the specific claim? No · Methodological quality: low · Certainty of evidence: see overall assessment of the claim

    Original publication · Scientific details

    Study explained simply
    What did the researchers want to find out?

    Review vitamin K intake and VKA stability.

    How was the study done?

    Systematic review.

    How many people, animals or samples were studied?

    15 studies, 1,838 patients.

    What was actually found?

    Low intake linked to instability; supplements may help unstable patients.

    How large was the observed effect?

    No pooled estimate.

    What do the results mean in everyday life?

    Avoiding greens does not make warfarin more stable.

    What are the study's limitations?

    Narrative; overlapping studies.

    What does it say about Elawady's specific claim?

    Argues against avoidance; supports consistent intake.

    Do the results apply to Germany and Europe?

    Universal.

    What can explicitly not be concluded from this study?

    Cannot give a precise effect size.

    Scientific details →

Studies with mixed or unclear results (1)

  • How much vitamin K changes warfarin effect

    Schurgers LJ et al.. Blood 2004 · PMID 15231565 · DOI 10.1182/blood-2004-04-1525
    Otherindependent cross-checkabstract checked★ key study

    In anticoagulated volunteers, INR fell significantly only from 150 micrograms of daily vitamin K1 upwards; spinach and broccoli meals had short-lived effects.

    INR effect from 150 ug/day; food-borne vitamin K effects short-lived.

    Does the study support the specific claim? Partly · Methodological quality: moderate · Certainty of evidence: see overall assessment of the claim

    Original publication · Scientific details

    Study explained simply
    What did the researchers want to find out?

    Find the vitamin K dose that disturbs anticoagulation.

    How was the study done?

    Step-wise supplement doses and test meals.

    How many people, animals or samples were studied?

    Healthy anticoagulated volunteers.

    What was actually found?

    Effect began at 150 ug/day; vegetable meals had brief effects.

    How large was the observed effect?

    Threshold 150 ug/day; clinically relevant in 25%.

    What do the results mean in everyday life?

    Small, irregular servings of greens matter less than often feared.

    What are the study's limitations?

    Not patients; supplements; size not in abstract.

    What does it say about Elawady's specific claim?

    Partly supports and partly limits the claim.

    Do the results apply to Germany and Europe?

    Universal.

    What can explicitly not be concluded from this study?

    Cannot quantify risk of bleeding or clotting.

    Scientific details →

Regional context

Germany / EU

Phenprocoumon is the main vitamin K antagonist in Germany; similar principle applies.

Egypt

Not specific.

What applies in my country?

General scientific assessment

Potentially true Partly true: big sudden changes in greens can shift warfarin's effect, but consistent intake is safe and avoidance is not advised; the archive reverses its own source's conclusion.

The following areas of food safety are relevant to this statement:

  • Pesticides and pesticide residues
  • Contaminants (heavy metals, PFAS, PCBs, dioxins, nitrate)
  • Pathogens (Salmonella, Campylobacter, etc.)

Fruit and vegetables

Choose a country to see the checked information for it.

Limits: legal rules describe what is allowed, not what every single food contains. Measurement data come from samples and are meaningful only together with their method details.

Country of residence or purchase Compare with another country

References

  1. Role of dietary vitamin K intake in chronic oral anticoagulation: prospective evidence from observational and randomized protocols.. Franco V et al.. Am J Med 2004 · PMID 15121490 · DOI 10.1016/j.amjmed.2003.12.036
  2. Dietary vitamin K variability affects International Normalized Ratio (INR) coagulation indices.. Couris R et al.. Int J Vitam Nutr Res 2006 · PMID 16941417 · DOI 10.1024/0300-9831.76.2.65
  3. Interaction Between Dietary Vitamin K Intake and Anticoagulation by Vitamin K Antagonists: Is It Really True?: A Systematic Review.. Violi F et al.. Medicine (Baltimore) 2016 · PMID 26962786 · DOI 10.1097/MD.0000000000002895
  4. Vitamin K supplementation can improve stability of anticoagulation for patients with unexplained variability in response to warfarin.. Sconce E et al.. Blood 2007 · PMID 17110451 · DOI 10.1182/blood-2006-09-049262
  5. Effect of Vitamin K Intake on the Stability of Treatment with Vitamin K Antagonists: A Systematic Review of the Literature.. Dentali F et al.. Semin Thromb Hemost 2016 · PMID 27232386 · DOI 10.1055/s-0036-1581105
  6. Effect of vitamin K intake on the stability of oral anticoagulant treatment: dose-response relationships in healthy subjects.. Schurgers LJ et al.. Blood 2004 · PMID 15231565 · DOI 10.1182/blood-2004-04-1525

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