How can excessive intake of pineapple increase INR?

I disagree with the previous answer provided by "inactive" on Aug 12, 2018.
Eating spinach and broccoli will NOT jack up your INR. These are vegetables high in Vitamin K, which warfarin works against, and may decrease your INR if consumption is suddenly increased. However, the dose of warfarin prescribed for you takes into account your regular intake of Vit K, so if your INR is staying around 3.0 and you can keep a consistent level of Vit K intake, then don't change anything. Many reasons can cause INR to go up, but the ones you mentioned, pineapple juice may be the biggest culprit. Pineapples contain bromelain, which can increase INR if consumed in large amount.

Spinach and broccoli can jack up your INR level. Mango is another factor contributes to the INR level. Pineapple juice can increase your INR as well because it contains Vitamin K. Any fruits or juice containing Vitamin K can have effects.