All recipes are for 2 servings unless noted. Oil is canola oil and salt is kosher salt.

Vitamin K Content List

The link below has a list of the Vitamin K content of common vegetables in Japanese cooking. Data is mostly from the Food Composition Database of the Ministry of Education, Culture, Sports, Science and Technology of Japan.


What about Vitamin K?

Those who take warfarin, an anticoagulant, are instructed to watch for food containing lots of Vitamin K, because of the mechanism of the drug. Warfarin blocks the formation of Vitamin K (K1 and KH2), which is essential for generating coagulation factors in the liver. So taking too much Vitamin K could weaken the drug's effectiveness.

Leafy greens are high in Vitamin K (K1). As long as you eat them in moderation, there should be no problem, especially when you have been eating them on a regular basis. In the US, the recommended intake of Vitamin K for adult men is 120 µg/day and 90 µg/day for adult women. Vitamin K guidelines in Japan are 75 µg/day for adult men and 60-65 µg/day for adult women.

In Japan, natto is always additionally mentioned at the top of the list of food to avoid if you take warfarin. Natto excels at encouraging production of Vitamin K in your body, which could significantly affect thrombotest figures (indicators to determine effectiveness of warfarin) even if you eat natto only one time.

Vitamins and Supplements Lifestyle Guide (WebMD)

(Last updated: May 3, 2016)

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