If you’ve been diagnosed with heart disease, chances are your doctor has prescribed a blood thinner to prevent dangerous clots. At the same time, you may have read about vitamin K2 and its promise for heart and bone health. But can you take these together? Could the supplement help or hurt? Understanding how they interact can help you make safer choices, and this article explains it all.

Why People With Heart Disease Take Blood Thinners

People with heart disease often need blood thinners, also called anticoagulants, because their risk of harmful blood clots is higher. Here are the most common reasons:

• Atrial fibrillation (AFib) — This heart rhythm problem can let blood pool in the heart, leading to clots that might travel to the brain and cause a stroke.
• Heart attack or artificial heart valves — Damaged heart tissue or valve replacements can lead to clot formation.
• Deep vein thrombosis or pulmonary embolism — Clots in the leg veins can break loose and travel to the lungs, which can be dangerous and potentially deadly.

Blood thinners help keep the blood flowing smoothly and lower the chances of these events. These drugs don’t actually “thin” the blood, but they slow the clotting process, which reduces the chance of blockages in arteries or veins.

Antiplatelet medications are sometimes referred to as blood thinners, but they work differently from anticoagulants. This article will focus primarily on anticoagulants, because these are the medications that interact most directly with vitamin K. While antiplatelets play a key role in heart care, they are not known to be significantly affected by vitamin K intake.

Common anticoagulants include warfarin (Coumadin, Jantoven), apixaban (Eliquis), and rivaroxaban (Xarelto).

What Vitamin K2 Is and Why People Use It

Vitamin K isn’t a single nutrient — it’s a group. The two key forms are:

• Vitamin K1 — Comes from leafy green vegetables and blueberries
• Vitamin K2 — Found in animal-based and fermented foods like cheese, egg yolks, and natto (fermented soybeans)

Both vitamin K1 and vitamin K2 fall under the umbrella term “vitamin K” because they play related roles in the body, especially in blood clotting and calcium metabolism. The key difference is that vitamin K2 remains in the body longer and may have additional benefits for bones and arteries.

The Potential Benefits of Vitamin K2

Research suggests that vitamin K2 supports several aspects of health. Although promising, current research is still in the early stages. More clinical trials are needed to confirm these findings and better understand how vitamin K2 affects different health conditions.

The following are potential benefits of vitamin K2.

Bone Strength

Vitamin K2 activates a protein called osteocalcin, which helps calcium stick to bones. This may improve bone density and reduce the risk of fractures, especially in postmenopausal people and older adults.

Healthy Blood Vessels

Vitamin K2 helps prevent calcium buildup in the arterial walls. Too much calcium in arteries can lead to calcification (or hardening) and raise cardiovascular risk. Some observational studies suggest people with higher vitamin K2 intake have fewer heart-related problems.

Proper Clotting

Vitamin K2 helps your blood clot normally, which is important for healing and recovery. This clotting function is also why people on anticoagulants must be cautious when taking vitamin K supplements.

How Vitamin K2 Can Affect Blood Thinners

Now, let’s discuss how vitamin K2 can affect specific blood thinners.

Vitamin K2 and Warfarin

Warfarin works by blocking the body’s vitamin K recycling system. This makes the blood less able to clot, which helps prevent strokes and clots. But when you add vitamin K2, either through diet or supplements, it can compete with warfarin and make it less effective.

This can be dangerous if not closely monitored. For example, someone who adds a vitamin K2 supplement without adjusting their warfarin dose might suddenly have a much lower INR (a lab value that measures clotting speed). That makes the blood more prone to clots, which warfarin is meant to prevent.

To avoid this, doctors encourage people on warfarin to keep their vitamin K2 intake consistent. You don’t need to avoid vitamin K-rich foods like leafy greens or eggs, but your intake should stay steady from week to week. Your care team may also adjust your warfarin dose or check your INR more frequently if changes occur.

Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs), which include apixaban and rivaroxaban, don’t depend on vitamin K to work. They block specific clotting factors in the blood, which makes them less sensitive to diet. That means vitamin K2 is less likely to interfere with these drugs. However, research is still limited on high-dose vitamin K2 supplements and their interactions with these medications.

Because these drugs aren’t routinely monitored with blood tests like warfarin is, it’s harder to catch early signs of trouble. That’s why it’s still wise to talk with your healthcare provider before starting any new supplement — even if the risk seems low.

The Risks of Combining Vitamin K2 and Blood Thinners

Taking vitamin K2 while on blood thinners isn’t always dangerous, but it does come with risks. These risks are mostly tied to changes in how your blood clots.

If your vitamin K intake increases suddenly, it might weaken the effects of your blood thinner, especially warfarin. Your blood could clot too easily, increasing your risk of stroke or deep vein thrombosis.

Even small shifts in diet or supplement use can cause your INR to move outside the safe range, especially with warfarin. People who change their vitamin K habits without medical supervision may face unpredictable results.

How To Get Vitamin K2 Safely if You’re on Blood Thinners

The safest approach is to be consistent and informed. If you’re taking blood thinners, talk to your doctor before changing your vitamin K habits, whether that means adding a supplement or changing your diet.

Foods like natto, egg yolks, certain cheeses, and fermented vegetables provide modest, steady amounts of vitamin K2. Eating these regularly, without major swings, allows your body and medication to stay balanced.

If you and your doctor decide that a supplement is right for you, start with a low dose. You’ll likely need more frequent INR tests at first, and your medication may need adjusted. Never start or stop a supplement without medical guidance.

So, Is Vitamin K2 OK?

Vitamin K2 may offer real benefits for bones and blood vessels, but if you take blood thinners, especially warfarin, it can affect how well your medications work. The safest strategy is to work with your doctor, keep your diet steady, and be cautious with any supplement changes.

It’s not about avoiding vitamin K2 completely. It’s about balance. With the right guidance and awareness, you can protect your heart, support your bones, and manage your medications safely.

Talk With Others Who Understand

MyHeartDiseaseTeam is the social network for people with heart disease and their loved ones. On MyHeartDiseaseTeam, members come together to ask questions, give advice, and share their stories with others who understand life with heart disease.

Are you on blood thinners and thinking of trying vitamin K2? Share your experience in the comments below, or start a conversation by posting on your Activities page.