The most important thing is to keep your diet stable, as this means that your warfarin requirement is also likely to be stable. Don’t make any radical changes without discussing them with your GP.
Food that is high in vitamin K, such as liver or vegetables such as Brussels sprouts and broccoli, can inhibit the action of warfarin. However, rather than leaving these out of your diet, make sure you enjoy a constant amount regularly. This will mean the level of vitamin K in your bloodstream will remain fairly constant, increasing the likelihood that your INR level will remain consistent and stable.
There are reports that cranberry juice can increase the effect of warfarin, so it’s best to avoid drinking this. It’s also important to follow the recommendations for safe alcohol intake and don’t drink a large amount in one sitting.