Vitamin K and Warfarin side effects. When vitamin K is too much?

Vitamin K and Warfarin interaction

Vitamin K and Warfarin may fight each other. If you’re in the medication of Warfarin, better inform your physician for your eating habits. Sometimes vitamin K is too much.

What is Warfarin used for?

Warfarin, sold under the brand name Coumadin among others, is an anticoagulant, meaning it’s a blood thinner drug. Warfarin reduces the formation of blood clots. 

Warfarin can prevent blood clots in veins and arteries.

Finally, the most common use of Warfarin is to reduce the risk of stroke and heart attack.

Vitamin K and Warfarin side effects.

Vitamin K helps your blood clot. Otherwise, we would bleed excessively.

Moreover, the wounds wouldn’t be easily healed, as we would bleed too much. 

Vitamin K is very important for the proper function of the liver. The liver needs vitamin K to make some of the clotting factors.

Blood clotting factors help to make blood clot. 

On the other hand, Warfarin makes your blood clot more slowly.

In a sense, vitamin K and Warfarin fight each other.

Too much vitamin K isn’t good for you.

So, vitamin K and Warfarin compete with each other.

Vitamin K helps to clot the blood, while Warfarin acts as a human blood-thinner.

For this reason, it’s important to inform your doctor about your eating habits.

If you’re under a Warfarin prescription, you shouldn’t change drastically your diet without informing your doctor.

Warfarin dose can effectively thin your blood, only if you consume about the same amount of vitamin K every day. 

If you start eating foods rich in vitamin K, your doctor may increase your Warfarin dose.

When vitamin K is too much?

The richest foods in vitamin K are dark leafy greens.

For instance, Brussel sprouts are particularly rich in vitamin K. A cup can provide more than 200% DV (Daily Value).

Warfarin may be less effective if you suddenly increase the consumption of them.

If you under a Warfarin prescription and you eat a standard American diet, going plant-based can be tricky.

You should inform your doctor about your new eating habits, in order to adjust the dose of the drug.

How much vitamin K for health benefits?

The leafy greens are the healthiest food you can eat. They are packed with nutrients and are low in calories.

Just one serving of green leafy vegetables per day may help to slow cognitive decline with aging (1).

Green leafy vegetables are a cheap option if you want to boost your daily antioxidant content, as they contain micronutrients and other phytochemicals, that have powerful antioxidant properties (2).

If you eat many green leafy vegetables you can experience potent health benefits.

Try eating green vegetables every day. It’s an important step towards a healthy life.

For instance, the consumption of green leafy vegetables, along with vitamin C-rich fruits and vegetables, appears to have a protective effect against coronary heart disease (3).

Additionally, the daily consumption of green leafy vegetables, not only helps you stay healthy, but also may help you live longer (4).

You can find a list of the richest vegetables in vitamin K, here.

Also, you can find more for the health benefits of vitamin K, here.


  1. Nutrients and bioactives in green leafy vegetables and cognitive decline – Prospective study
  2. Potential of commonly consumed green leafy vegetables for their antioxidant capacity and its linkage with the micronutrient profile.
  3. NCBI: The effect of fruit and vegetable intake on risk for coronary heart disease.
  4. Healthy lifestyle and preventable death: findings from the Japan Collaborative Cohort (JACC) Study.