Based on NIH | Is it safe to eat broccoli while taking warfarin, and will its vitamin K content affect my INR or require dose adjustments?

You can eat broccoli while taking warfarin, but it’s important to keep your intake consistent because its vitamin K can lower warfarin’s effect and change your INR. ^{[1] [2]} Eating broccoli does not have to be avoided; instead, try to eat a similar amount from week to week so your warfarin dose stays appropriate. ^{[1] [2]} If you suddenly increase or decrease broccoli or other vitamin K–rich foods, your INR may shift and your dose might need adjustment. ^{[2] [3]}

Why broccoli matters

• Broccoli contains vitamin K (phylloquinone), which the body uses to help blood clot. ^[3] Too much vitamin K can reduce warfarin’s anticoagulant effect, potentially lowering your INR. ^[3] Official guidance for warfarin advises a normal, balanced diet while avoiding large, sudden changes in vitamin K intake. ^{[3] [4]}

What the evidence shows

• Patient education guidance notes that foods such as broccoli can be eaten, but the key is not changing the amount you eat from day to day or week to week. ^[1] Clinical guidance similarly emphasizes keeping a steady amount of vitamin K in your diet to avoid INR swings. ^[2]
• In clinical studies, a single serving of broccoli did not push anticoagulation outside the therapeutic range, but repeatedly eating high amounts over several days tended to reduce anticoagulation and could require dose changes. ^{[5] [6]}

Practical tips for eating broccoli on warfarin

• Aim for consistency: If you usually eat broccoli two to three times per week, it’s reasonable to continue that pattern rather than suddenly eating much more or cutting it out. ^{[1] [2]}
• Keep portions steady: Similar portion sizes help your care team keep your INR stable and your warfarin dose accurate. ^{[2] [3]}
• If you plan a diet change: Talk with your healthcare team before you significantly increase or decrease broccoli or other leafy greens, since INR may need closer monitoring during the change. ^{[3] [4]}

INR monitoring and dose adjustments

• Warfarin has a narrow therapeutic range, and its effect can be influenced by dietary vitamin K, so regular INR checks are essential. ^[4] After your INR is stable, testing continues periodically, with frequency based on your clinical situation. ^[4] If your vitamin K intake changes or your INR drifts, your warfarin dose may need to be adjusted. ^[4]

Bottom line

• You do not need to avoid broccoli on warfarin, but you should keep your intake consistent to help maintain a stable INR. ^{[1] [2]} Sudden increases in broccoli or other vitamin K–rich foods can lower your INR and may require dose adjustments, so coordinate any diet changes with your healthcare team. ^{[2] [4]}