Interaction: Warfarin and Liver

• Liver is often seen suggested as a source of vitamin K2 and beef liver in particular has been recommended as a good dietary source. 
• From the tables below it seems that while the beef liver tested contains mk-4, it is not a particularly good source 
• However, most studies have not tested for long-chain menaquinones, mk-6 to mk-13, which are produced by the bacterial fermentation in the stomachs of cattle and provide them with a readily absorbable source of vitamin K2. 
• When absorbed from the gut these reach the liver first where they appear to remain. 
• This can be seen as very little long chain menaquinones were detected in any of the other meat or organs of cattle. 
• The only small study that has tested for these found quite high levels of menaquinones 11, 12, and 13

as a comparison, a 100g of cabbage/brocoli has 100mcg of vitamin K, while that of spinach contains 200mcg.

References:

1. Vitamin K. Academic Press, 3 Mar 2008
2.  https://honey-guide.com/2014/03/10/menaquinones-k2-and-phylloquinone-k1-content-of-animal-products-and-fermented-foods/ 
3. http://apjcn.nhri.org.tw/server/info/books-phds/books/foodfacts/html/data/data3e.html