Warfarin Vitamin K Tracker
Your vitamin K intake should be consistent, not necessarily low. This tool helps you track your daily vitamin K intake to maintain stable INR levels. Enter the foods you consume daily and see how your intake compares to your average.
Enter your data to see your vitamin K consistency
Warfarin saves lives. It keeps dangerous blood clots from forming after heart valve replacements, deep vein thrombosis, or atrial fibrillation. But for every person who finds stability on warfarin, there’s another who ends up in the ER because of a sudden spike in INR-or worse, a clot that slipped through because their INR dropped too low. The problem isn’t the drug. It’s the food on your plate.
Why Warfarin Is So Sensitive to What You Eat
Warfarin works by blocking vitamin K, a nutrient your body needs to make clotting factors. Too much vitamin K, and warfarin loses its power. Too little, and you’re at risk of bleeding. It’s not about avoiding vitamin K altogether-it’s about keeping your intake consistent. A single large serving of kale or spinach can throw your INR off by 0.5 to 1.0 units in just a few days. That’s enough to push you from a safe range into danger.
The goal? Keep your daily vitamin K intake steady. Most adults need between 90 and 120 micrograms per day. You don’t need to count every microgram-but you do need to know which foods pack a punch and avoid wild swings.
The Food List: What to Watch Out For
Not all greens are created equal. Here’s a breakdown of foods that can interfere with warfarin, grouped by vitamin K strength:
Very High Vitamin K (Over 500 mcg per 100g)
- Kale (817 mcg)
- Collard greens (623 mcg)
- Parsley (616 mcg)
- Seaweed (599 mcg)
- Spinach (483 mcg)
- Swiss chard (450 mcg)
- Turnip greens (421 mcg)
One cup of cooked spinach? That’s nearly 900 mcg of vitamin K. If you normally eat a salad with lettuce and suddenly swap it for a big bowl of spinach, your INR could plummet. Don’t quit spinach-just eat the same amount every day.
High Vitamin K (100-500 mcg per 100g)
- Broccoli (raw, 102 mcg)
- Brussels sprouts (177 mcg)
- Green tea (106 mcg)
- Asparagus (cooked, 70 mcg)
- Cabbage (cooked, 60 mcg)
- Edamame (50 mcg)
These are common in meals. A side of steamed broccoli or a cup of green tea might seem harmless. But if you drink green tea every morning and suddenly stop for a week, your INR can creep up. Same if you skip Brussels sprouts during holidays and then binge on them at Thanksgiving.
Medium Vitamin K (25-100 mcg per 100g)
- Lettuce (raw, 30 mcg)
- Green beans (25 mcg)
- Avocado (21 mcg)
- Blueberries (19 mcg)
- Carrots (13 mcg)
These are generally safe. You can eat them freely without worrying too much. But even here, consistency matters. If you go from eating blueberries daily to never eating them, your body adjusts-and your INR might shift.
Hidden Triggers: Juices, Supplements, and Alcohol
It’s not just vegetables. Some drinks and supplements are just as dangerous.
Cranberry Juice
One study found that drinking 8 ounces of cranberry juice daily raised INR by 1.0 to 2.0 units. One Reddit user saw their INR jump from 2.4 to 4.1 in just a few days. That’s a bleeding risk. Avoid it completely.
Grapefruit Juice
Grapefruit messes with the liver enzyme that breaks down warfarin. Even a small glass can increase your INR by 30%. If you’ve ever had a glass with breakfast, stop. It doesn’t take much.
Alcohol
More than two drinks a day lowers warfarin’s effectiveness. Heavy drinking can make your INR drop, raising your clot risk. But even moderate drinking on an empty stomach can spike your INR. Stick to no more than two drinks on two days a week-and never binge.
Supplements That Can Kill You
- Fish oil (omega-3): Increases bleeding risk by 25%. Avoid doses over 1,000 mg daily.
- Garlic supplements: Can raise INR by 0.8 to 1.2 units. Fresh garlic in food? Fine. Pills? Skip them.
- Ginkgo biloba: Doubles bleeding risk. Used for memory? It’s not worth it on warfarin.
- Coenzyme Q10: May reduce warfarin’s effect. Not proven, but too risky to try.
Always check with your anticoagulation clinic before taking any supplement-even “natural” ones.
Real Stories: What Works
One user on PatientsLikeMe, u/StableINR, kept their INR in range for 18 months by eating exactly one cup of spinach salad every single day. No more. No less. They didn’t avoid spinach-they mastered it.
Another user, u/WarfarinWarrior, had their INR spike after daily cranberry juice. They stopped it. Their INR dropped back to normal in three days.
Studies show people who keep a food journal are 76% more likely to stay in their target INR range. Apps like MyFitnessPal let you track vitamin K intake. Set a goal: keep your daily vitamin K within 10-15% of your average. That’s it.
What to Do Every Day
Here’s your simple daily routine:
- Take warfarin at the same time every day. No skipping.
- Eat about the same amount of vitamin K every day. If you had kale yesterday, have kale today.
- Avoid cranberry juice, grapefruit juice, and alcohol beyond two drinks twice a week.
- Don’t start or stop any supplement without talking to your doctor.
- Log your meals in an app or notebook. Even a quick note helps.
Warning Signs: When to Call Your Doctor Immediately
Warfarin can cause bleeding. It’s not rare. Know the red flags:
- A cut that won’t stop bleeding after 5 minutes
- Bloody or black, tarry stools
- Severe headache or dizziness
- Unexplained bruising or swelling
- Red or pink urine
One in five warfarin users will have a bleeding event in a year. Most happen because of diet changes, missed doses, or new supplements. Don’t wait. Call your clinic or go to the ER if you see any of these.
The Bottom Line
You don’t need to eat bland food. You don’t need to give up greens. You just need to be consistent. The same amount of vitamin K every day. The same routine. The same awareness.
Warfarin is still the best choice for mechanical heart valves and many other conditions. It’s cheap. It’s proven. But it demands respect. Your food isn’t the enemy-it’s your partner in staying safe.
Stick to your plan. Track your meals. Talk to your anticoagulation team. And remember: stability isn’t luck. It’s discipline.
Can I eat spinach if I’m on warfarin?
Yes, you can eat spinach-but keep the amount consistent. One cup daily is fine. If you normally eat spinach and suddenly stop, your INR may rise. If you start eating a big bowl every day, your INR may drop. Consistency matters more than avoidance.
Does green tea affect warfarin?
Yes. Green tea contains about 106 mcg of vitamin K per 100g. Drinking one cup a day is usually okay if you’ve been doing it consistently. But if you start drinking three cups daily or suddenly quit, it can change your INR. Stick to your usual habit.
Is cranberry juice really that dangerous?
Extremely. Cranberry juice blocks the liver enzyme that breaks down warfarin, causing INR to spike. One case study showed an INR rising from 2.4 to 4.1 after daily consumption. Avoid it completely. Even "sugar-free" versions have the same effect.
Can I drink alcohol on warfarin?
Moderation is key. No more than two standard drinks on two days per week. More than that can lower warfarin’s effect and increase clot risk. Drinking on an empty stomach or binge drinking can spike INR and cause bleeding. When in doubt, skip it.
Should I take vitamin K supplements?
No. Unless your doctor specifically prescribes it, avoid vitamin K supplements. They can make warfarin less effective and increase your risk of clots. Get your vitamin K from food-consistently-not pills.
How often should I get my INR checked?
When you first start warfarin, you may need checks weekly. Once stable, every 2-4 weeks is typical. But if you change your diet, start a new medication, or get sick, get tested right away. Your INR can shift fast.
Are there apps to track vitamin K intake?
Yes. MyFitnessPal has a vitamin K tracker. Others like Cronometer and Fooducate also list vitamin K content. Log your meals daily. Patients who track their diet are 22% less likely to have out-of-range INR results.
What if I forget to take my warfarin?
If you miss a dose, take it the same day if you remember. If it’s already the next day, skip it and resume your normal schedule. Never double up. Call your anticoagulation clinic for advice. Missing doses is a top cause of clots.
Next Steps: What to Do Today
Start simple:
- Check your last INR result. Is it in range?
- Look at your last week of meals. Did you eat a lot of kale one day and none the next?
- Remove cranberry and grapefruit juice from your fridge.
- Download a food tracking app and log your meals for three days.
- Call your anticoagulation clinic and ask for a copy of their dietary guidelines.
Staying safe on warfarin isn’t about perfection. It’s about routine. You’ve got this.
