The main foods to avoid when taking blood thinners are those containing vitamin K, notes Mayo Clinic. These foods are mostly green leafy vegetables. Vitamin K assists with blood clotting.
Vitamin K works in opposition to warfarin and other blood thinners, and, therefore, it should not be taken in conjunction with any of them, as Mayo Clinic explains. Foods to avoid are greens, including spinach, kale, brussels sprouts and parsley, as well as chard, mustard greens and collard greens. People taking blood thinners should also avoid green tea. Some beverages can increase the effect of warfarin, leading to bleeding problems. These drinks include alcoholic drinks and cranberry juice.